Tektronix 7854 User manual

PAGE
L IST
O
F I LLU
ST
R ATIO N
S .................................. iv
L IST O F TA BLE S ...... . . . . . . . . . . . . . ..... . .................
ν
SERV ICI N G SA F ETY S UMM A RY . . . . . ........... . ........... vi
S E CTIO N
l---
.GE N ERA L I NF O RM ATIO N
SERV ICE M A NU A L ............................ 1-1
7854 R ELATED DOC UMEN
TATIO N ............. 1-1
I N STA L LATIO N ...................................
1-2
I NITIAL I N S PE CT I O N ........................... 1-2
P O WER SO UR CE
I NF
O
RM ATIO N ............... 1-2
P
O
WER-UP
CO
N DITIO N S ...................... 1-3
PR ESE T CO
N DITIO N S .......................... 1-4
O
PER ATI N
G
P OSITIO N ......................... 1-4
O PER ATI N G TE MPER AT URE .................... 1-4
TEKTRONIX
F I EL D S E R V ICE ....................... 1-4
P ACKAGI N G F O R SH I PMEN T ..................... 1-4
SE CTIO N 2--T HE O R Y O F O PER ATIO N
BL OC K DIAG
R A
M .... . . . . ........................... 2-1
D E SC
R I P TIO N
..................................... 2-1
DETAI LE D CI R C U IT OPERATION
...................... 2-5
TE K T R
O
N IX D R AFTI N G CO NVEN TIO N ..........
2-5
CA BL I N G
.........................................
2-5
M OD E SW ITC H AND CALIBRATOR ................
2-5
M OD E SW ITC H . . .............................. 2-5
CA L I BR ATO R ..................................
2-8
MAIN
I N TER F AC E ................................
2-8
PLUG-IN I N TE R FAC E ...........................
2-8
V ERTICA L CH A NNEL SELE CT L OGIC ........... 2-8
H O R IZO N TA L CH A NNEL SELE CT L OGIC .......
2-11
M AI NF RA ME L OGIC ............................. 2-11
H O R IZONTA L L OGIC .......................... 2-12
Z-AXIS L OGIC ................................ 2-15
H
O
R
IZO
N TA L B I N A RY .........................
2-17
VER TICA
LB
I
N
A
RY
............................
2-19
PLUG-IN B I N A R Y .............................
2-21
C L OC K GENER ATO R
.......................... 2-23
VER T ICA L C H O PPE D BL A NK I N
G
..............
2-25
C H O P CO U NTE R ..............................
2-2 .6
VER TICA L M OD E L OGIC
......................
2-28
TRAC E SEP A R ATIO N ......................... 2-29
Α T R IGG ER SELE CTO R ...................... . . . .
2-30
Α T R IGG ER C H A NN E L SW ITC H ............... 2-30
LE FT A N D R IG H T TRIGG E R
PRE A MPL
I F
I ER S ........................ ... ... 2-31
Α T R IGG ER OU T PU T A MPL I F I ER
........ ... ...
2-31
VER TICA L
SIG
N A L
O U
T A MPL I F I
ER
. . . . . . . . . . .
2-32
Β TRIGG ER SELE CTO R .................... ... ...
2-32
Β TRIGG ER CH A NNEL SW ITC H . . . . . . . . . . . . . . . 2-33
L E FT A N D R IG H T T RIGG ER
PRE A
MPL
I F
I ER S ........... . . . . . . . . . . . . . . . . . . . 2-33
ΒT R IGG ER O U TP U T A MPL I F I ER .... . . . . . . . . . . 2-34
VER TICA L C H A NN E L
SW
ITC H
. . . . . . . . . . . . . . . ..... 2-34
C H A NNEL SW ITC H .............. . . . . . . . . . . . . . 2-36
O U T PU T V O L TAG E RE G U LATO R S
.............
2-36
VER TICA L C H A NNEL SE LE CTO R . . . . . . . . . . . . . . 2-37
R IG HT A N D LEF T" C H A NNEL F EEDBESID E ..... 2-37
S E CO N DA R Y S UPPL Y RE G U LATO R S .......... 2-37
VER TICA L PICK OF F AMPL I F I ER ..................
2-38
P ICK O F F A MPL IFI ER ................. ... ... ...
2-38
V O L TAG E /C URREN T R EG U LATO R ............ .
2-38
P AG E
VER TICA L AMPL I F I ER ............................ 2-38
DELAY L I NE .................................. 2-38
A U XI L IAR Y I NPU T A MPL I F I ER ................. 2-39
H IG H - FR EQ UEN CY A MPL I F IER ................ 2-39
O UT PU Γ A MPL I F I ER .......................... 2-39
O U TP U
T PR OTECTIO N ........................ 2-40
BEAM FINDER/BEAM F I N D ER OV
ERRID
E ..... 2-40
H O R IZO N TA L CH
A
NNEL SW
ITC H AN D
P
IC
K
O
FF AMPL I F I ER
..........................
2-40
H
O
R IZO N TA L CH A NNEL SW ITC H .............. 2-40
P ICK OFF A MPL I F I ER .......................... 2-40
Χ - Υ DELAY CO MP E N SATIO N (OPTION 02) ...... 2-41
H O R IZO N TA L AMPL I
F IER ........................
2-41
I NPU T A MPL I F I ER / BE A MF I N D ER .............. 2-41
D R I VER AMPL I F I ER S A N D ACTI VE PE A K I N G . . 2-42
O U TPUT A MPL I F I ER S ......................... 2-42
O U TP U T SIG N A L S ............................... 2-42
SAWTOOT H AMPL I F I ER ....................... 2-42
GAT E AMPL I F I ER ............................. 2-43
SI N G LE SWEEP R ES E T ....................... 2-43
Z-AXIS A N D F OC U S A MPL I F IER ................ . 2-43
Z-AXIS A MPL I F I ER ............................ 2-43
A U TO- F OC U S C H A NN E L SW ITC H AN D
A MPL I F IER ................................... 2-44
H IG H V
O
L TAG E P O WER SUPPL Y A N D C R T
......
2-44
P O WER TRA N S F O RM ER ...................... 2-44
+130
V SUPPL Y
............................. . 2-44
C R T HEATER ................................. 2-44
A N OD E V O L TAG E MUL T I PL I ER ............ .. . 2-44
C RT CAT H OD E SUPPLY .................... ... 2-45
CAT H OD E S UPPL Y RE G UL ATO R ........ ... .. . 2-45
CO N TRO L -G RID DC RE STOR ER ......... ... ... 2-45
F OC U S-G RID DC RE STO RER ............ ... ... 2-45
C RT CO N T R O L ............................ .. . 2- β5
CO
NVER TER/ R ECTI F IERS ................. . . . . . . .
2-46
L I NE I NPU T ............................... ...
2-46
I NVER TER START ......................... . . . . 2-47
I NVER T ER ........................... ... . . . . . . 2-47
O V E R - V O L TAG E STOP ..... . ...... . . . . . . . . . . . . 2-49
I NVER TER CO N T R O L .......... . . . . . . . . . . . . . . . . 2-49
P OWER UP L OGIC ........................ ... 2-50
L O W - V O L TAG E RE CTIFIERS ................ ... 2-50
L
O W -
V
O
L TAG E RE
G U
LATO R
S
A N D
F A N B
OA
R D ............... ..... . . . . .
. . ...... 2-50
O P ERATIO N A L AMPL I F I ER P O WER
SUPPL I E S .................. ... ... ... . ........ 2-51
+50 V RE G UL ATO R ......... . .. ... ... ......... 2-51
-15 V RE G U LATO R ..... . . . . . . . . . . . ........... 2-51
+5 V RE G U LATO R ....... ... . . . . . . . ........... 2-53
+15 V RE G U LATO R ..... . . . . . . . . . . ............ 2-53
-50 V RE G UL ATO R . . . . . . . . . . . . . . . . ........... 2-53
F A N CIR C U IT . . . . . . . . . . . . ... .................. 2-53
G
R ATIC
ULE L IG
H T
S UPPL Y ....... . ........... 2-53
FR O NT-P A NEL CO N T R O L S .. ... ..................
2-53
KE Y B OA R D SYSTE M .
. . . . . . . . .. ..................
2-54
C L OC KDI V ID E R . . . . . . . . . . .. ... ............... 2-54
KE Y B OA R D SCA NNER ...... . ................. 2-54
DATA BU S BUF F ER . . . . . . . . ... ............... 2-57
KE Y B OA R D STO P /SCA N . . . . . . . . .............. 2-57
KE Y B OA
R D
F LAGS . .......................... 2-57
KE Y B OA R DS . . . . . . . .......................... 2-57
Ί
TABLE
OF
CONTENTS

TA"-, - -LE
OF CONTENT%r
- -~
(CONT)
P AG E
CO
LUMN SCA
NNER ..........................
2-58
R
O W SCA NNER ..............................
2-58
LE D D R I VER
S ................................
2-58
VER TICA L A ND H O R IZO N TA L
SA MPLER ......... 2-58
SA MPL I NG BR IDG E ......................... .
. 2-58
ST R O BE INPU T
............................... 2-59
V ERTICA L A ND H O R IZO N TA L ST R
O
BE ........
2-59
V O L TAG E F O LL O WER S
......... . . . . . . . . . . . . . . 2-59
C H A
NNEL S W ITC H ......................... . .
2-59
D
E CO UPL I NG F I L T ER S
. . . . . . . . . . . . . . . . . . . . . . . . 2-60
DIGITIZER CO NTR
O
L L
OGIC
. . . . . . . . . . . . . . . . . . . . . 2-60
DATA/C L OC K SE LE CT
. . . . . . . . .
. . . . . . . . . . . . .... 2-60
BU S CO NT R O L . . . . . . . . . . .
.
..
. . . . . . . . . . . . . . . . . 2-61
ADD RE SS SELECT . . . . . . . . . . . . . . . . . . . . . . . . . .
. . 2-62
I
N TE RN A L ACQ U I RE ADD RE SS G ENER ATO R . .
2-63
ADD RE SS G ENER ATO R ... . ......................
2-63
COUN T ER ....................................
2-63
M OD E W O RD L ATC H .........................
2-63
Α W O R D BU FF ER ............................
2-63
EN D-O F -CO U NT D ETE CTO R ...................
2-63
W O
R
D/C L OC K S ELE CT .......................
2-64
Β W O RD ADD RE SSCOUN T ER
................ 2-64
ADD
RE SS O UT PU T ...........................
2-64
DIGITIZ ER C L OC K
............................... 2-65
C L OC K /SO UR C E S ELE CT .................. . ..
2-65
C L OC K DE L AY ............................. ..
2-66
SO UR CE RE STA RT ............ . . . . . . . . . . . . . . .
2-66
GATED OSCI L LATO R ................... . . . . . .
2-66
BUR ST
COUN
T ER . . . . . . . . . . . . . . . .  . . . . . 
2-67
D M A CO N TRO L . . . . . . . ..
. . . . . . . . . . . . . . . . . . . . . ... 2-67
BU S RE Q UE ST L OGIC . . . . . . . . . . . . . . . .........
2-68
BU S G R A NT L OGIC . . . . . . . . . . . . ..............
2-68
D M A TI M I N G L OGIC .........................
2-68
DIGITIZ ER S WEEP COUN TER .....................
2-69
ACQ U
I
RE W O R D REGIST ER ................... 2-7 ρ
S W EE P COUN T E R ............................
2-70
GATE S ELE CT ................................
2-70
CO MPL ETE S WEEP DETECTO R ...............
2-70
ACQ U I RE STO P ............................. .
2-70
DIGITIZ ER .......................................
2-71
COMP A R ATO R ...............................
2-71
APPROXIMATION G ENER ATO R ................
2-71
D/ Α CONVER TER .................... . ........
2-72
A PPR OXI M ATIO N
DATA LATC H
...............
2-72
V O L TAG E REFER EN C E
...... . . . . . . . . . . . . . . . . . .
2-74
C L OC K CO N DITIO N ER ............... . . . . . . . . .
2-74
SIG N AT URE A N A L YSIS . . . . . . . . . . . . . . . . . . . . . ..... 2-74
M IC R O PR OC E SSO R A ND CO N T R
O
L . . . ...........
2-75
CL OC K
. . . . . . . . . . . . . . . . . ... . . . . . . . . . . . . . . . . . . . 2-75
I N TERR
U
PTS A
ND CO N T R O L ..................
2-76
DATA BU S TR A N SC E I VER
S ...................
2-76
TR A N SC E I VER CO NT R O L ..................... 2-77
CO N T R O L BU S ...............................
2-77
C
RU O U
TP
U TS ...............................
2-77
ADD RESS D E COD ER
.........................
2-78
ADD RESS
BU FFERS ..........................
2-78
RE AD O NL Y MEM
O
RY .......................... . 2-78
ADD RE SS BU S BUF F ER ..................
. . . .
2-78
MEM ORY ... . . . . ..........................
. . . .
2-78
R OM CO N TRO L .............................
. 2-79
FP LA ........ . . . . . . ........... . . .
. . . . . . . . . . . . . 2-80
P AG E
DATA
BU S BUF FER
........................... 2-80
R A
N DO M ACCESS ME M ORY .....................
2-80
MEM O RY .......................
. . . . . . . . . . . . . . 2-80
ADD RE SS BUFFER S . . . . . . . . . . . . . . . . . . . . . . . . . .
2--80
R A M CO N TRO L ....... . . . . . . . . . . . . . . . . . . . ....
2-80
I NPUT/O U T PU T DATA BUFFER S . . . . ..........
2-81
MEM O R Y B AC K-UP P O WER S W ITC H .........
2-81
WR ITE PR OTECT . . . . ..... . . . . . . . .............
2-81
RE
ADO UT ACQ U I RE . . . . ..... . ...................
2-81
TIMER
. . . . . . . . . . . . . . .
......................... 2-86
TIME-SLOT CO
UN
T E R ........................
2-86
C H A NN E L . COUN TER ..........................
2-87
CO LUMN A N D R O W DATA S W ITC HE S .......
2-90
CO LUMN A ND R O W DE COD ER S .............
2-91
C H A R
ACTE
R EN
COD ER S ...................... 2-91
P OSITIO N ADD RE
SSCO UN T E R ............... 2-91
BU
FF E RS
.....................................
2-92
RE ADO UT BU S
CO
NTR
O L .................... 2-92
VER TICA L /H O R IZO N TA L DIS P LAY
A N D CO NTR O L .
. ........... . . . . . . . . . . . . . . . . . . 2-92
BL OC K D E SC R IP T IO N . . . . .
. . . . . . . . . . . . . ....... 2-93
DIS PL AYD/ Α A N DA MPL I F I ER .................
2-109
H
O R IZO N TA L A ND VER TICA L D/ Α
CO NVER T ER
..... . . . . . . . . . . . . . . . . ............
2-109
H O R IZO N TA L C
URR ENT S UMMER A ND
A MPL I F I ER .................................
.2-109
VE RTICA L C URREN TS
UMMER A ND
AMPLIFIER .................................
.2-111
VER TICA L A ND H O R IZO N TA L VE
CTO R
G ENER ATO R ........................ . . . . . . .
.2-111
O U TP U TS ELE CTO R ..........................
2-113
Z-AXIS DRIVE ................................
2-113
A
N
A
L OG SCO PE CO N TR O L L OGIC ............
2-113
G ΡΙΒ

...................................... . . . .
.2-113
THE
IEEE 488-1978 STA N DA R D ..... . . . . . . . . 2-114
THE H A N DS HA KE PR
OC E SS ...... . . . . . . . ....
2-114
G
P IA
....................... . ..... . . .
. . . .
....
2-117
MPU I N TERFAC E . . . ........... . . . . . . . . . . ...
.2-117
G P I B I N T ERF AC E ..... . . . . . . . . . . . . . . . . .......
2-117
CO NTR O L A N D TI M I N G L
OGIC . . . . . . . . . . ... .2-117
G
P I
B ADD RE SS S ELE CTO R . . . . . . . . .........
.2-120
RE A R PANEL CO NNECTO R . . . . . . . . . . . .........
.2-120
MOTHER B
OA
R D
. . . . . . . . . . . . . . . ................ 2-120
A U XI L IA R Y RE G U LATO R . . . . . . . . ...............
.2-124
+12 V O L T RE GU LATO R ......................
2-124
+5 V O L T RE GU LATOR ... . ...................
2-124
-5 VO LT S W ITC H I N G
........................ 2-124
E XC E SSI V E C URREN T STO P .................
2-125
F A
UL T PROTECTION
......................... 2-125
S E CTIO N
3-MAINTENANCE
PREVEN TATI VE M AI NT EN AN
CE
......................
3-1
CA B I NE T P A NEL RE M
O V
A
L
.......................
3-1
C LE A N I NG .............................
. . . . . . . . . . . 3-1
EXTERIOR ...................................
. . 3-1
C R T ............................. . . .
. . . . . . . . . . . 3-1
INTERIOR ........................
. . . . . . . . . . . . . . 3-2
V IS
U
A L I
N S PE CTIO N ................ . . . . . . . .......
3-2
S
EM
ICO ND U CTO R C HE CKS ...... . . . . . . . . . . . . . . . . .
3-2
PER IODIC
ELE CTRICAL AD JUST MEN T . . . ..........
3-2

TABLE OF
CONTEN

(CONT)l
P AG E
TRO UBL ES H OOTI N G . . . . . . . . . . . . . . . . . . . . . . . . . . . . ... . .
3-2
TRO
UBLE S H OOTI N G AIDS ........................ 3-2
DIAGRAMS ....................................
3-2
CIR C U IT B OA R D I LLU ST R ATIO
N S .............. 3-3
S
ERV
ICE IDE N TI F ICATIO N TAG .................
3-3
T R O UBLE S H
OOTI N GC H A R T ...................
3-3
T RO UBLE S H
OOOTI N G TREE
................... 3-3
AD JU ST MEN T A N D
T E ST POINT
LOCAnONS . . 3-3
CO MP O NEN T CO L
O
R
CODI N G . . . . . . . . . . . . . . . . .
3-3
S EM ICO N D U CTO R LE ADCO
NF IG UR ATIO N S
. . . . 3-3
MUL TI- PIN CO NNE CTO R S
. . . . . . . . . . . . . . . . ..... . 3-3
A
N
A
L OG T R O UBLE S H OOTI N G E
Q U
I
PMENT ........ 3-3
DIGITA
L T R O UBLE S H OOTI N G E
Q U I PMEN T . . ..... . 3-7
DIGITA L T R
O UBLE S H OOTI N G TEC HN
IQ UE S . ...... 3-9
PR ES E T CO N
DITIO N S
......................... 3-10
A N A L OG
TROUBLESHOOTING T E C HN IQ
UES ...... 3-10
1 . C HE C K CO N T R
O L SETTI N GS
............... 3-10
2 . C HE C K
ASSOCIAT E D E Q U I PMEN T .........
3-10
3 . V IS U A L
CHECK
............................ 3-10
4 . C HE C K I N ST RUMEN T
AD JU ST MEN T ... . . . .
3-10
5 . ISOLATE T R O UBLE
TO Α CIR C U IT . . . . . . . . . 3-10
6 . CHECK VO L TAG E
S
A N
D W A VEF O RMS . . . . .
3-10
7 . C HE C K I N DI V IDU A L
CO MP O NEN TS . .......
3-11
8 . REP AIR A N D AD
JU ST THE CIR C U IT ........
3-11
T R
O UBLE S H OOTI N G THE H
IG
H -
EF FICI EN CY
P
O
WER
-S UPPL Y UN IT ........................
3-11
G ENER
A
L ....................................
3-11
PREL I M I N A R
Y PR OC E D URE ...................
3-12
TRO UBLE S H
OOTI
N
G PR OC E D URE
.............
3-12
CO RRE CTI VE MAINTENANCE
........................
3-16
OBTAI
N I N G R EP L AC EMEN T P A
R TS ..............
3-16
SO L
D
ER I N G TEC HN IQ UE S .......................
3-17
CO
MP
O NEN TREM O V A L AN D
REPL AC EMENT ... .
3-18
DIS PL
AY UN IT K IC K STA N D . . . . . . . . . . . . . . . . . . .
3-18
P O WER
-S UPPL Y UN IT REM O V A L . . . . . . . . . . . . .
3-18
P O WER
-S UPPL Y UN IT I N STA LL ATIO
N . . . ...... 3-18
CAT H OD E - R AY
T UBE REM O V A L ..............
3-20
CAT H OD E - R
AY T UBE REPLACEMENT .........
3-21
CI R C U IT B OA R
DS
............................ 3-21
PLUG-IN I N TER F AC E
CO NNE CTO R S
........... 3-27
S EM ICO N D U CTO R S
........................... 3-27
I N TERCO NNE CTI N G P I
N S .....................
3-32
PU S HBU TTO N
SWITCHES ....
. ..... . ........ . . 3-33
G R ATIC ULE L IG H T
BULB S ............ . ....... 3-33
P
O WER - TR A N S F O RMER . . . . . . . . . . . . . .........
3-33
ADJUSTMENT A F TER REP AI R .................
3-33
S E CTIO N 4--CA L I
BR ATIO N
U SI N G T HE S E
PR OC E D URE S .................. 4-2
PER F O RM A N C E
CHE C K S UMM A R Y ............ 4-2
AD JU ST MEN T I N T E R
V
A
L .....................
4-17
T EK T R O NIX F I EL DS
ERV IC E ...................
4-17
'TEST
E Q
U I PMEN T RE Q U I RE D
... . . . . . . . . . . . . . . . . . 4-17
S PE
CIA L F IXT URE S
. . . . . . . . . . . . . . . . . . . . . . . . . . . 4-17
T E ST E Q
U
I
PMEN T A L TE RN ATI VE
S . . . . . . . . . . . . 4-17
P AG E
P A R T
I- PERFORMANCE C HE C K ..... . ........ . . . . . .
4-21
I N
D
E X TO PERF O RM A N C E C
HE C K PROCEDURE
. . 4-21
P ER
FORM A N C E C HE C K P
OW ER-UP S E Q UEN
C
E . .
4-21
Α .
Z-AXIS
A
N D DIS P LAY
........................ 4-22
Β .
CA L
I
BR ATO R A N DO U T PU T
SIG N A L S ......... 4-23
C . TRIGG ER
SYST E M
............................ 4-29
D . H O R IZO N TA
L SYST EM ........................
4-31
Ε . VER
TICA L SYST EM ...........................
4-34
F . VER TICA
L
AN
DHO R IZO N TA L PICK
O FF
SYST EM . .
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-37
P A R T 11---AD JU
ST MEN T A N D PERF O RM A N
C E
C HE C K ... . . . . . . . . . . . .
. . . . . . . . . . . . . . . . . . . . . .
. . . . . . . . 4-42
I N D E X TO AD JU ST MEN
T A N D P E R F OR M A N
C
E
C HE C K PROCEDURE
.............................
4-42
AD
JU ST MEN T A N D PERF
O RM A N C E C HE C K
P
O W E R- UP SE Q UEN C E ..........................
4-43
Α .

P
O WER

SUPPLY ..............................
4-44
Β .
Z-AXIS AND DIS PL AY ...............  , . 
,
4-47
C . CA
L I BR ATO R A N D O U T PU T
SIG N
A
L S . . . . . . .
. .
4-54
D . T R
IGG
ER
SYSTEM
............... . ........
. . . .
4-60
F . VER TICA L
SYSTE M . . . . . . . . .
. . . . . . . . . . . . . .....
4-71
GA . DIS PL AYSYST
EM ..........................
4-79
G B . DIS PL AY
SYSTEM ...........................
4-83
GC . DIS P
LAY SYST E M . . .........................
4-87
Η . VER
TICA L A N D H O R IZO N TA L P
IC
K
O FF
SYSTE M . . . . . . . . . . ...............................
4-90
Ι.
CA L C U LATO R K E Y B
OA
R
D ................... . η -1 ρ 4
SE CTIO N
5----IN
STR UMEN T O P TIO N S
OPTION 02 ....................................
5-1
OPTION
03
....................................
5-1
OPTION
78 ....................................
5-1
OPTION OD ...................................
5-1
OPTION 2D ...................................
5-1
OPTION 1S .................................
. .
. 5-1
OPTION 2S . . . . . ...........
. . . . . . . . . . . . . ..
. . . . . 5-1
P O WER CO R D OPTIONS
. . . . . . .
. . . . . . . . . . . . . . . . 5-2
WH IC H O P TIO N
S DO E S YO UR 7854
HAVE? ... 5-5
S E
CTIO
N
6-
-R EP L AC E A BLEELE
CTRICA L P A R TS
S E CTIO N7---DIAGR A M
S A N D CI R C U IT B
OA R D
I
LLU STRATIO N S
S E CTIO N 8---REPL
AC E A BLE ME C H A N
ICA L P A R TS
C H A N G E I NF
O
RM
ATIO N

Ι

Ι U
2-1

B loc k
Diag r am
. ..............
. . . . . . . . . . . . . . . . . .
2-2
2-2

M ode
Switc h /Cali brator block d iagra m . . . . . . . . . . 2-7
2-3

( Α )
L ogic Diagram of t he V e r tical Ch a
nn
el
Switch Logic on the M ain
Interface . ( Β ) Input/
output
table of the V ertical Channel
Switch
logic on the M ain Interface
......... . ...... . . . . . 2-9
2-4

Detailed b lock
diagram of the M ainframe
L ogic circuit ...................................
2-10
2-5

Breakdown
of separate stages within
Horizontal L ogic IC (U116) showing inputs
an d output
for eac h stage ....................
2-11
2-6

(
Α ) L ogic diag r am fo r Α Swee p
Loc kou t stage ;
( Β ) Ta b le of i npu t/o u t pu t com b i n atio
n
s
........ 2-12
2-7

(
Α ) L ogic diagram fo r Β Swee pLock
o u t stage ;
( Β ) Ta b le of input/output com
b i n ations ........ 2-13
2-8

( Α ) L ogic d iagra m fo r Alternate
Pulse
Gene r ato r stage ; ( Β )
Ta
b
le of in p ut/outp u t
combinations ... . . . . . . .
. . . . . . .................. 2-14
2-9

Input an d output p i nsfor
Ζ -Axis L ogic
IC (U190) . . . . . . . . . .
.... . . . . . . . . . . . ..... . ...... 2-15
2-10

( Α ) L ogic d iagram
for Ζ -Axis L ogic stage ;
( Β ) Table of input/output
combinations . . . . . . . . 2-16
2-11

Input and o utput
p ins for H orizontal B inary
IC
(U4358) ................................
. . . . 2-17
2-12

(
Α
) L ogic
d iagram for Horizontal B inary stage ;
( Β ) Table of input/output
combinations ........ 2-18
2-13

Input and output p
ins for Vertical B inary
IC ( U 52) ......................................
2-19
2-14

( Α ) Logic d iag
r
am fo
r V e r tical Bina r y stage ;
( Β ) Table of
input/output combinations .......... 2-20
2-15

Input and
output pins for t he p lug-in binary
IC (U82)
..... . . . . . . . . . . . . . . . . . . . ..............
2-21
2-16

( Α ) Logic diagram for Plug-in Binary stage ;
( Β ) I nput/output tables for U72 and e ntire
stage ...................... . . . . . . ..............
2-22
2-17

( Α ) Diagram of clock generator
stage ;
( Β ) I dealized waveform
for clock ............... 2-24
2-18

( Α ) L ogic diagra
m for V e r tical Cho pp ed
B lanking stage ; (
Β ) Table of input/output
combinations . . . . ............ ... ...
. . . . . . . ..... 2-25
2-19

Idealized
waveforms for Vertical Chopped
Blanking
stage .......................... ... . . . 2-26
2-20

( Α ) I nput and o utput
pins for C hop counter
IC (U22) ; ( Β )
I dealized waveforms for C hop
Counter stage ..................................
2-27
2-21

L ogic
diagram of Chop Counter stage .........
2-28
2-22

L ogic d iagram of V ertical
M
ode
L
ogic
stage ... 2-29
2-23

( Α ) L ogic diagram of Trace Separationstage
;
( Β ) Table of input/output
combinations ........ 2-30
2-24

Detailed block diagram of
the Α T rigger
Selecto r circuit . ... . . . .......................... 2-31
2-25

Detaile
d b loc k d iagram of t h eΒT rigge
r
Selecto r ci r c u it ........ . .......................
2-33
2-26

V ertical A mp lifie r detaile d b loc k d iag
r a m ....... 2-35
2-27

( Α ) F unctional
d iagram of V ertical Channel
Switc h ; (
Β ) Table showing signal d istribution
by the
V ertical Channel Switch .................. 2-36
2-28

U 150
internal circuitry representation .......... 2-39
2-29

Ιηρυτ
/ ουιρυ t relations h i ps for t he Auto-
Focus Ch a
nn el Switc h . . . .....................
2-44
2-30

Detaile
d b loc k d iagram of t he Conve
rte r /
R
ectifie r s circuit .............. . . . . . . . . .........
2-46
2-31

( Α ) R ep
r
ese
n tation of Inverte r stage .
I d ealize d
waveforms of ( Β ) total Inverter current,
IC,
(C)
V oltage across CR41 and (D) V oltage
across
primaries of Τ 10 a nd Τ 35 .............. . . . . . . .
2-48
2-32

Detailed B lock Diagram of
the Converter/
R ectifiers circuit ...............................
2-52
2-33

Detailed B lock
Diagram of the K eyboard
system ........................................
2-55
2-34

Ti m ing Diagram
fo r t h eK eyboa rd System ..... 2-56
2-35

Co mp a
r
ison se
qu ence of S u ccessive
A ppr
oximatio n R egister for two ra
n
dom
voltage
sam ples ...............................
2-73
2-36

Cloc
k Pu lse delay . ............................
2-74
2-37

Timi n grelations hips of
t h e fo u r ph ase,
3-MHz clock . ........... . ..
. . . . . . . . . . ......... 2-75
2-38

L ocation of R eadout
words on the crt
identifying
the originating p lug-in a nd
c hannel . ................
. . . . . . . . . . . . . ......... 2-82
2-39

Character
Selection M atrix for t he 7854
R eadout Acquire system ............... .
. . . .
..
. 2-83
2-40

Typical
readout display where only
channel 2
of
the R ight V ertical and Β
H orizontal units
is d isplayed ...................................
2-84
2-41

Detailed Block Diagram of
the R ea d out
Acquire system
............................... 2-85
2-42

O u t pu t waveforms of
Time r stage ............. 2-86
2-43

Time relatio n s h
i p
of
t he Time Slot (TS)
p ulses produced
by U2320 .................... 2-87
2-44

Typical encoding
scheme for V oltage-Sensing
plug-in unit .
Coding shown for αcalibrated
deflection
factor of 100 m icrovolts (inverted) ... 2-89
2-45

Idealize'
current waveforms of : ( Α ) R ow
Analog
data . ( Β ) Column A nalog data .........
2-90
2-46 Α

W
aveform Data F low . . . . . . . . . .................
2-94
2-46 Β

Ch aracter Data F low . . . . . . . . . . . . . . . ...........
2-96
2-47

7854 C h a r acte r Set ............... ... . .......
2-100
2-48

Crt Display ..........................
. . . . . . . . . 2-110
2-49

Display of
Character on crt ....... ... . . ..... .2-112
2-50

GPIB
T hree W ire H andshake state d iagram ... 2-115
2-51

GPIB
Handshake flowchart ................ . .
.2-116
2-52

GPIB timing
d iagram ......................... 2-119
3-1

Color code for r esistors and capacitors . . . . . . . . . 3-4
3-2

Semiconductor lead configurations .........
. . . . .
3-5
3-3

Orientation of multi-pin connector hol d ers ...... 3-6
3-4

Analog Test B oard (067-0912-00) inter-
connections ....................................
3-7
3-5

Typical d igital test/troubleshooting
configurations . .................................
3-8
3-6

C urr ent se n sing wavefo
rm at R84 ............. 3-13
3-7

L ocatio n of sc r ews used fo
r d isc h arging
li ne stor age ca pacito
r
s . . . . ....................
3-14
3-8

Current
waveform of Τ 30 s howing burst
operation
at line voltage of about 60 volts .... 3-15
3-9

Current
waveform at Τ 30 for n ormal inverter
operation at line voltage of 115 volts ......... 3-16

-)NS (CONT)
.Ι

1
3-10

W aveform at ΤΡ 34 on
the A23-Inverter b oar d
with t he line voltage
at about 20 volts . . . . . . . . 3-16
3-11

R ecommended desol d ering
se q uence for
m ulti-pin
devices
. ....... . . . . . . . . . . . . . . . . . . . . . .
3-17
3-12

U se of the
Display U nit k ickstand . . . . . ........
3-19
3-13

P ower Supply
Unit securing screws and
service identification
tag location ..............
3-20
3-14

L ocation of securing screws
used for All-
Main Interface b oard removal .................
3-23
3-15

Correct p
lacement of power t
ransistor and
mounting h ardware in rear h eatsink ...........
3-25
3-16

IC code
number locations ..................... 3-28
3-17

H ypcon assembly
removal and replacement
.... 3-30
3-18

Coaxial en d -lead
connector assembly ..........
3-32
3-19

E xplo
d ed view of circuit b
oard pin and
ferrule ........................................
3-32
3-20

Correct procedure for
pushbutton switch
removal
and replacement ......................
3-34
4-1

Typical
d isplay when checking
Χ
-
Υ Phase
relationships
................................
. .
4-33
4-2

Typical d isplay
when checking Χ - Υ
Phase
r elationships
. . . ...... . . . . . . . . . .
. .
. . . .
. . . . ..... 4-69
5-1

L ocation of Option
i d entification tags ...........
5-5
1-1

P ower-Cord Color
Conductor I d
entificatio n ...... 1-2
1-2

P ower-Cord
And Plug Identification
Infor m
ation . . . . . . . . . .. .. .. .. .. .. .. .. .. .. . . .
1-3
1-3

Self-Test F
ault Codes . . . . ....................

1-4
2-1

Common L ogic
Gates Illustrations ..............
2-6
2-2

Ιηρυτυ /Output Combinations
for Α T rigger
Channel Switch ...............................
2-32
2-3

Input/Output Combinations
for ΒT rigger
C hannel Switch
. .......................
.
. . . . . . 2-34
2-4

R OM E N ABLING
............ ... ....  . 
2-79
2-5

Sta nd a r d R
eado u t F o r mat ..................... 2-84
2-6

Ch annel A ddr
ess Co de .................  .
2-88
2-7

Signal

L ine

Description

Table ................. 2-101
2-8

M other Board
Signal Definitions ..............
2-121
3-1

Self-Test F au lt Co d
es .......................  . 3-9
3-2

R
eco m men d e d P owe r S upp ly T
r oubles h ooti ng
Se quen ce . ...............................
. . . . .
3-12
3-3

Typical P
ower-Supply R esistance
. . . . . . . . . . . . ...
3-13
3-4

Burst V
oltage Test P oints ....
. . .... . . . . . . . . ..
.
3-14
3-5

IC Code/Shunt
R esistor
Replacement V alues . .
3-28
4-1

Cali br atatio n P roce
dur e Electives ................
4-1
4-2

P erformance
Check S ummary ................... 4-2
4-3

Test Equipment ....................  .  . .

4-17
5-1

Option Information
Locator ..................... 5-2
V

AFETY
""UMMARY

7854 FEATURES
The TEKTRONIX 7854 Oscillosco pe wit h W avefo r m
Calc u lato r com b i n es t h e featu r es of αh ig h - perfo rm ance plug-in oscillosco pe wit h α
wavefo rm -o r ie n te dde d icate d -f un ctio nd igital pr ocesso r .
The wave f o rm p rocessor provi d es e qu ivale n t-time sa mp le d digitizi n g of wavefo rm
s to
400
mega h e r tz e qu ivale n t-ti m e bandwi d t h . T h e
pr ocesso r ca nbeo p e r ate d f r o m eit he r k ey b oa rd (f r o n t- pan el meas u
reme
n
t k ey b oa rd o r d etac h a b le W avefo rm Calc u lato r k ey b oa rd) o r
r emotely ove rt he G P I B (Ge n e r al Purp ose Inte r faceBus) .
Pr og r a m ming, co n sisti ng of αse r ies of comma nd s sto r ed fo r late r exec u tio n , is availa b le to si mp lify meas ur
e
m
e
n
ts
w h ic h mu st b e r
e p eate
d .

--
Ed iti n g a nd executio n is co n t rolled eit h e r f r o m t he W avefo rm Calc u lato r o rt h e G P I B .

GENE, AL INFO ~1~'*AAAATION
This sectio n co n tai
nsα
basic d escri p tion of t he Service Manual content, information on instr u ment installation, p ower
and p ower cord requi r ements, operating temperat u re consi d erations, pack aging fo r s h i p me n t, a nd instr u ment r ep air
services .
S ERV IC E M ANUA L
T h e following is α b rief d esc r i p tio n of t he infor
m ation
contai ned in t h is man u al .
Section 1----Ge n eral Info r mation contains i n stallation
instr u ctio n s, ope r ating tem p erature conside r atio n s,
Te k tronix F iel d Service, and instrument pack agi n g
information .
Section
2--=-T
h
eory of Operation contains αbasic b loc k
d iagram d escri
p
tion and αd etailed circuit a n alysis t h at
may be useful
for servici ng or operating
t h e
instrument .
Sectio
n
3--
.-Maintenance describes routine
an d
corrective maintena n ce p roce du res wit h detailed
inst ru ctio ns fo r t r ou b les h ooting t he analog ci r cu its .
Diagnostic tro ub les
h
ooting equipment an d proce d ures
can
be p
u rc
h ase d sepa r ately, o r r efe r repair
to yo u
r
Te ktronix F iel dOffice .
Section
4
.---Cali b ratio n contai ns proce du res to ch ec k
t h e o pe r atio n al p erformance an d electrical
cha r acteristics of t he i n str u m e n t . Α p erfo r ma n ce
ch ec k su mma
r y p r
ovi d es α cr oss r efe r en ce b etwee n
t h e specifications an d relate d adju stment proce du
res .
Section 5-I n strument Options contains αd esc r iption
of available optio n s and locations of i n co r porate d
information fo r t h ese options .
Sectio n 6-- R e p laceable E lectrical Pa r ts contains
information necessary to or der re p laceable pa r ts a nd
assem b lies relate
dto
t
he
electrical
f
u nctions of t h e
i n strument .
Section
7-----Diagrams an dCi r cu it B
oa
rd Ill u
strations
incl
ud
es d etaile d ci r cuit sc he m atics, locations
of
assem b le d boa r d s with in t h e instrument, voltage and
waveform information, ci r cu it b oar d com p onent
locators, and locations of adju stments to ai d i n t he
p erformance of t
he A dj
ustment and Perfo r m ance
ch ec k portion of t h e Cali b ration proce d ure .
Section 8--- Re p laceable M ec ha n ical P arts incl ud es
informatio n necessary to or de r re p laceable
m ec h anical parts a nd sh ows ex p loded drawings w h ic h
i den tify assemblies .
7854RE LATED DOC UMEN TATIO N
In add ition to t h e 7854 Service Manual, ot her pu blicatio n
s
a r e availa b le ; t h ey incl ud e t he O p e r ato r s Manual,
Diag n ostic Manual P ac k ageand Data S h eets .
O pe r ato r s Manual
T h e 7854 O p e r ators man u al co n tai ns i nstallation
i n st r uctio n s, sp ecificatio n s a nd operating info r matio n
fo
r
the sco pe disp lay, meas ur ement a nd wavefo r m calculator
k
ey
b
oa
rd ,
GP
I B ,
op tio ns a nd command lang u age .
Diagnostic Manual P ac k age
T he i n formatio n necessary fo r t r o ub les h
ooti ng t he digital
po r tio n of t he 7854 Oscillosco
pe consists of seve r al
in d ivid u ally p art n um bere d d oc u ments com b
ined in an
o rde r ly fash io n to pr o
du ce α "Diagnostic Manual
P ac k age" .
"7854 Diag n ostic T r ou b les h ooting U sing 067-0911- ΧΧ
Diag n ostic Test
I
n te
r
face" is t h e pr i n ci p al manual a nd is
bo und i nα3- r i ng b i nd e r to ena b le insertion of t he ot he r
supp ort doc u ments at t h ei r a p pro p riate locations .
Ot
her
s upp
ort d
oc
um
ents
i n
cl ude su pp le m en t manuals an d
data sh eets .
Supple
m ent M anuals . The supp lementary man u als
"7854
Sig n atu r e A n alysis Ta b les U si ng 067-0911- ΧΧ
Diagnostic Test Interface" ( P a r t n umbe r 070-2922- ΧΧ )
an d "Test P roce d ures fo r 7854 Diag n ostic T r ouble-
sh
ooti ng U sing 067-0911- ΧΧ Diagnostic T est Interface"
( P a rt nu m b er 070-2875- ΧΧ ) sh o u ld be i n se r ted be h i nd
t h e Pr ima r y Manual's "Sig n at ure Ta b les" a nd "rest
Pr oce d u res" ta b s res p ectively .
1-1

Th e manual for t h e "Diagnostic M emory
B oar d (067-
0961- ΧΧ )" co n tai n s service informatio n fo r t he special
circuit b oa r d containing t he d iag n ostic fir
mwa r e fo r
tro
ub les
h
ooti ng t
he
7854 .
Data
Sheets (
F
or Sup p ort- R elated T est F ixtures)
.
Data sh eets
fo r d
iag
n
ostic
r
elated ha rd wa r e include t he
following :
7854
Analog
Test B oar d (067-0912-00)---See
application u nd er Analog Tro ub les h
ooting Equ i pm e n t
in Section
3,
M aintenance .
7854 Exte nd er B oa rd , 44- P in (067-0913-00)---See
a pp licatio n un de r Digital T r o ub les h ooting E q u i p ment
i
n Section 3, M aintenance .
7854 E xtender B oa r d , 80- P i n
(067-0914-00)_--See
a pp lication unde r Digital T r oubles h ooti n g Equipment
i
n Sectio n 3, M aintenance .
7854 E xten der B oa rd , 124-Pin
(067-0915-00)--See
a pp lication under Digital
Trou b les h ooting Eq ui p me n t
i n Section
3,
M aintenance
.
INSTALLATION
I N ITIA L I NSPECT IO N
T h is inst ru ment was
inspecte d both mec h anically and
electrically befo r e s h ipme n t f r
om t
h
e factory to be fr ee of
mars or scratches
and to meeto r excee d all electrical
sp ecifications
.
U pon recei p
t,
i
n spect t he i n strume n t for
any ph ysical d amage w h ic h
may
h
ave been i nc urr ed in
t r a n sit .-
Then,
refer
to t
h
e Pe r fo r mance C h ec k P roce dur e
i n t he Cali br atio n section of
t
h
is Manual to ve r ify t he
electrical performa n ce of t he i n st rum
en t . If mec ha n ical
da m age
o
r p e r formance deficiencies a
r e fo und , contact
you r local Te ktronix F iel d Office or
representative .
P
O W
ER
SOUR C
E
INFORMATION
T h is i n st ru ment will ope r
ate from eit he r α 115-volt or
230-volt no m i n al li n e-voltage
so u rce, 48 to 440 h ertz .
Operating V oltage
T h e L I NE VO L TAG E SE LECTO R switc h (locate d
on t h e
rea
r
pa
n
el of t
he
7854 Oscillosco p e m ainf r ame)
allows
selection of
115-volt o
r
230-volt n ominal li n e voltage
ope r
atio
n .
To
select
t he correct n ominal line voltage, fi r st
chan ge t
hep
ower cord and p l u g to matc h t he p
owe r -
so
urce r ece p tacle (if
necessa r y) . T hen, u se α small
sc
r ewdrive r
to move t
h
e L I NE V O L TAG E S ELE CTO R
switc h to t he desi r ed r ange
.
CA
UTION
To pr event d amage to t he
instrument, always
c h ec kt h e setti ngs of t h eL
I NE V O L TAG E
SE LECTO R switc h locate don
t h e r ear p a n el
of t h e 7854 Oscillosco p e mai
n frame befo re
co n necti ng t he inst ru m e n
t to t h e line-voltage
sou r ce .
P owe r Cord Infor m ation
Α p owe r
cord wit h t he a ppr o pr iate pl ug configuratio n is
s upp
lie d with
eac h instrument . F or your co n venie nce t h
e
color-co d ing
of t
hep
owe
r
cord co nd uctors is given i n
Tab le 1-1 . Also, s h ould
you re qu i r e α p owe r -cor d p l ug
ot her t h an t h at s upp lie d ,
refe
r
to t h e P owe r -Co rd a nd
P l ug I den tification Table 1-2 .
T h is instr u ment ope r ates fr om α si n gle- ph ase
p owe
r
sou rce, a nd
h
as α detac h able t h ree-
wi
re
p owe
r
cor d wit hα two- p ole, t h ree-
te
r
minal gro un d ing-ty p e p l ug . Th e voltage to
gro
und (ea rt h )fr om eit he r pole of t h e p owe r
source m u st not excee d t h e maxi m u m rated
operating voltage, 250 volts .
B
efo
re ma k ing
connection to t h e p owe r
sour ce, determine t h at t h e instrume n t is
a djuste d to match t h e ν oltge of t he power
so u r ce, and h as αsuitable p l ug (two- p ole,
t hr
ee-te
r
minal,
g ro
und i n g type) .
Th
is i
n
st ru
me n t
is safety class 1 equipment
(I E
C* d
esignation) . Α //
accessible con du ctive
p arts a r e directly connecte d
t
h
ro u g h t h e
gro und ing con du cto r of t h e power
cor
d
to t
he
gro u nding contact of t he p ower cor
d
.
T h e r efo r e, t h e powe r p lug must
only be
i n se r ted in α mating receptacle wit hα
ground ing contact . Do not d efeat t he
gro und i ng con n ectio n . A ny interruption of t he
groun d
ing connection can cr eate an electric
s h oc k h aza rd .
Fo r
electric s
h
oc
k pr otection,
t
he g
r oun d ing
connection
m
ust
b
e
m
a de b efo re ma k ing
connection
to t h e instrument's in pu t or
ou t pu t terminals .
1-2

TA BLE 1-2
P owe r -Cord And Pl u g I d entificatio n I n
fo
r
m atio n
M e m ory
Back-up
P
ower
Two fe m ale banana j ac k s (on t he rea r p anel
of t he 7854
Oscillosco p e mainframe) allow a pp licatio n
of abo u t 6 .25
V d o (0 .7 Α m axim u m)
to p rovide back-up power for t he
volatile sto r age d evices u se d for p
rocessor memo r y . Th e
instrument is f use p r otecte d for ap p licatio n
of any
voltages app lie d to t he MEM
O
RY B
AC K-UP P O W ER
I NPU
T
up to +50 volts (dc p l us peak
ac) .
Wh en
power is
first app lie d to t he MEM O R Y B AC K-UP P O W ER I NP
U
T
t he associate d re d indicator lig h ts to in d icate t h
at t
he
f use h as n
ot
b lown .
To pr eve n t loss of d ata fro m memo r y
due to α
p owe r fail ur e,
apply
me m
o
r y
back-up p ower .
POWER-UP CO N DITIO N
S
Wh en t h e 7854 is t u rne d on (wit hou t memo r ybac k
up
p ower app lie d ), t he d igital pr ocesso r ru n
s four self-
check i ng tests . Alt h oug h t hese tests a r e not
all-inclusive,
t h ey i nd icate if m a j o r portions of t he processo r
a
r
e
wor k ing p ro p erly . The self-test se quence o u
tline d b elow
begi ns w h en p ower is a pp lie d to t he 7854 .
Wh en p owe r is applied t he
followi ng
i n d
icato
r
s will lig h t : P O WER,
selected
p ositions of
t
h
e Α and Β TRIGG ER
SO U RC E
switc h es, a n
d all selecte d i nd icato r s on t he
p l u g-in u nits . Fo r
a pproximately t hree
secon ds afte r
power-up t he followi ng
i nd icators will r emain off :
all p ositio ns of t he
VE RTICA L and H O R IZO N TA L M
OD E switc h es,
all intensity i nd icators, all
red front-panel
( m eas ur ement keyboa rd ) a
nd W avefo r m
Calculato r i n d icato r s .
All positions of t he
VER TICA L and
H O R IZONTA L M OD E switc h
es, all Inte n sity
in d icato r s, an d all r ed -front- p anel
and
W avefor m Calc u lato r in d icators
will now
lig h
t .
Α fa u lt con
d ition fo und t h roug h any of t he
four tests
is in
d icate dwith
t h e lig h ts of t he
VER TICA L and H
O
RIZON
TA L M OD E switc h es .
F ault co nd ition
cod es are liste d in Table 1-3 .
B e su re to note t h e co de r eceive d
so t
h
at yo u
may more f u lly inform
t
he se r
vice p erso n
abo u t t he trouble .
1-3

If α fa u lt co de occ u rs, press any button of t h e
V
ERTICA L or H O R IZONTA L M OD E switc h es
an d t h e self-testing will co n ti nu e . T h en, refer
to
t h eP erformance
C
h
ec
k Pr
ocedure in t h e
Cali b ration section of t h is Manual to verify
t h e electrical p erformance of t he instrument .
Successful com p letio n of t he self tests is
in d icate d by t he iss u ance of t he a ud ible
warning to ne (if t he rea r - p a n el A U DI BLE
W ARN I NG switc h
is ON), a n d t h e
extinguis hing
of all red in d icators, t he S an d
Α Inte n sity indicators,
all
VER
TICA L M OD E
lig h ts exce p t LEF T, a nd
all
H
O R IZO N TA L
M OD E switc h lig h ts exce p t Β .
In addition, if
t he RE ADO U T intensity co n trol is set
to ab out
mi dra n ge, t h e m essage S ELF TE
ST
CO MPL ETE will be disp laye d
on
the c r
t .
PR E SET CO N DI T IO N S
After successf u l completion of t he processor self tests,
several pa r amete r s of t h e 7854 a r e set to pred etermine d
co nd itions . T
h
ese power-up co nd itions a r e :
C R T DIS PL AY mo de . . . . . . . . . . . . . . Set to SCO P E
P rogram M ode . . . . . . . . . . . . . . . . . Set to E X ECUTE
P rog r am M e m ory
. .
. . . . . . . . . . . . . . . . . . . . . . Cleared
V ERTICA L M
OD
E . . . . . . . . . . . . . . . . . . . Set
to LEFT
H O R I Z O N TA L M OD E . . . . . . . . . . . . . . . . . . Set
to
Β
Store d W avefor m Disp lay . . . . . . . . . N ot displayed ;
set to V ECTors
Ρ/ W ( P oints/ W aveform) . . . . . . . . . . . . Set to 512
Stac k Registe r s . . . . . . . . . . . . . . . . . . . .Cleared to 0
O PW (Operational W aveform) . . . . . . . . . . Set to 0
All waveform memory points . . . . . . . . . Set to t he
zero value (ce n ter h
orizo n tal
gratic u le line)
VZR ( V ertical Zero R eference)
. . . . . . . . . . Set to 0
(all
waveform memories)
V ertical Scale Factor . . . . . . . . . . . . . . . Set to 1

(all
waveform memories)
V ertical Scale F actor U nit . . . . . . . . . .Set to V
(all
wavefor m memories)
H orizontal Scale
Factor . . . . . . . . . . . . . Set to 1

(all
waveform
memories)
H o r izontal Scale F actor Unit . . . . . . . . Set to S
(all
waveform memo r ies)
Constant R egisters . . . . . . . . . . . . . . . . . . . . .Set
to 0
TT L Outp u t . . . . . . . . . . . . . . . . . . . . . . . . . . . Set H IG H
RSV Control

F lags
. . . . . . . . . . . . . . . . . . . . . . Set 0 Ν
O
PER A T ING P OSI T
IO
N
Α bail-ty pe sta n d, mo u nted on t he bottom
of t h e
mainframe, permits t he i n str u ment to be tilte d up abo
u t
10° fo
r
more conve n ie n t crt viewi ng .
OP
E RATI N
G
TE M PERAT U RE
T h e 7854 can be op erated in am b ient air tem p erat ures
b etween0° a nd +50° C, and can be stored in am b ient
tempe r atu r es from -55° to +75°C . Afte r being stored in
temperatures ou tsi
d e t h eoperating
limits, allow the
chassis tem pe r at u re to return
to
with i n
the operating
limits before a pp lyi n g p ower .
T h e 7854 Oscillosco pe mainframe is coole d by air drawn
in t h roug h holes in t h e top, si d e, an db ottom cabi n et
p anels an db lowno u t t hrough t he fan ex h a u st . To ensu re
prop er inst r ument cooli n g, maintai nthe clearance
p rovi d ed by t h e feet on t he b ottom cab inet
panel, an d
allow at least 2 inch es of clea r an ce at t he to p ,
sides,
and
r ear of t he instr u me n t .
If t h e inter n al tempe r ature of t he mainframe excee ds α
safe operating level, α t h er m al cutout will re p eate d ly
i n te r rupt t he i n strument p owe r supply . this con d ition
stop s w h en t h e te mp erature returns to α safe level .
TEKTRONIX
FIE L D
S E
R V ICE
Tek tronix F ield Service Centers an d t he F actory Service
Cente r p r ovide instrument re p air and ad j ustment
services . Co ntact your Te k tronix F iel d Of fice or
r ep resentative for f u rt her information .
P AC
K
AGI
N
G FO
R
SHIPMENT
If t h is instru m en t is to be sh i pped for long d istances by
commercial t r ans p ortation, we recommen d t h at t h e
instr u ment be pack aged in t he o r igi n al manne r . T h e
carto ns an d p ac
k
aging mate
r
ial in w h ic h your inst r ument
was
sh
ippe d
s
houl d b
e save
d
a
nd
used for t h is purp ose .
1-4

Also, if t h is inst ru ment is to b e
s
h i p
ped to α Te k tro n ix
Se r vice Ce n te r for se r vice o r r epai r ,
attac hα tag to t he
i n str u me n t sh owing t he followi ng :
Ow
n
er of t he
I n str u me n t (with a ddr ess), t he name of α pe r
so
n
at your
firm w ho ca n be contacte d , an d t h e co m plete
instr u m e n t
type a nd se r ial nu m be r . Also, list t he
Diagnostic
F ir m ware nu m b e r, a nd the Signature Ta b le
numbe
r
(i n dicated on t he r ear-panel S ERV IC E ID EN TI F
ICA TI O N
tag) . Pr ovide αdescription of t he service r
equire d .
If t he original pack
agi n g is unfit fo r u se or not availa b
le,
p ac k age t he inst ru me n t as follows :
1 . Obtai nα co rru gate d ca rdb oa rd ca r ton with α
375
p oun d test strengt h (fo r t he M ai n f r a m e) o r α
200 po und
test stre n gt
h (fo
r t he W avefo r m Calculato r ), a nd h
aving
i
n
side d imensio ns of no less t han six inc h es more t h an
t he i n
st ru me n t
d
imensions ; t h is allows fo r cush io n ing .
2 . S urround t he instr u ment wit h p
olyet h ylene sh eeti n g
to
p r otect t h e finis h .
3 . Cu s h io n t h e instr u ment on all si d es by tig
h tly packing
d
un n age o
r
ur et h ane foa m b etwee n t he ca r ton a
nd t h e
instr u me n t, allowin
g t h ree i n c h es on all sides .
4 . Seal
t
he ca
r ton wit hsh i pp ing tape o r wit h
an
in du
strial sta p le r .
5 . M ark the a ddr
ess of t he Te k t r o n ix Se r vice Ce nte r
a nd
yo ur r et ur n a d d
ress on t he carto n in on e or
more
p romi ne n t locatio ns
.
1-5

THEORY
OF OPERATION
T h is sectio n d esc r i b es
t
h e circuit
r y u se d i n t he 7854 Oscillosco
p e m ai n fra m e . T he d esc r iption b egins
wit
h
αdisc u ssio n
of t he inst ru me n t, u
si
n g t he
bloc k diag r a m sh own in F ig ur e
2-1
.
Next, eac h ci r cu it is d escri b ed in d etail wit h
s upp o r ting
ill u strations, w h en
a
ppr o p r iate,
to sh ow t he r elations h i pb
etwee n t he stages i n eac h ma j or ci r
cuit . Detaile d sc h e m atics
of eac h ci r cu it a r e located i n
t h e Diag r ams section at t h e rear of
t h is manual . Refer to t h ese
sch ematics t hr oug h out t he
following ci r cuit d esc r iption
for sp ecific valu es an d relatio nsh
ips .
BLOCK DIAGRAM
Th e following d iscussio n is
provi d ed to ai d i n u nde r sta nd i ng
t
h
e ove r all conce p t of t he 7854 befo r e t h e in d ividual ci r cuits
are discusse d in d etail . Α b
asic block diagra m of t h e 7854
is sh own in F ig ur e 2-1 . Only t he basic i n te r co n nections
betwee nthe i nd ivid u al b loc ks are sh own
on t h is diag r am . Eac h ma j o r ci r cu it wit h i n
the instrument is given αblock . T he
n umbe r
of eac
hblock
r efers to t h e com p lete circuit
d iag r am located at t he r ea r
of
t h is m an u
al
.
DESCRIPTION
Th e M ai n I nte r face circuit
connects ve r tical an d
ho r izo n tal signals f r o m the pl ug-in
com pa r tment to t h e
vertical an d ho r izontal d eflection syste m
s .
V ertical sig n
als to be displaye d on t h e c rt (cat h
od e- r ay
t u be) are a pp lied to t h e V e r
tical C ha nn el Switc h ci r
cuit
from both vertical p l u g-i n com p
a r tments . T he f r o n t p anel
VERTICA L MOD E switc h d etermi n
es w h et he r t he signals
f r om t he L EFT V ERT o r R IG HT V ERTcomp
a r tme n ts a r e
d is played on t h e crt . At t h is p oi n t
t
he
sig n al path is sp lit
into an an alog a nd α d igital pat h . F o r the a nalog p
at h , t he
selected
vertical sig n al(s) passes t h ro ug h α Delay
L i n e
a nd is t h e n amplifie
d by t he V e r tical Amplifier ci r c u
its to
b r ing it to t h e level n
ecessary to d rive t he vertical
d eflection p lates of t he c r t . T h ed
igital p at h b egins with
the V ertical P ic k off Am p lifie r w h ic
h con ve r ts t he push-
pull sig n als a p plied to it from t he V e r tical
C ha nnel Switc h
to t he si ngle-e nd e d signal re qu i r e dby
t he V e r tical
Sam p le r circ
u
it . After some d igital p r ocessi n g, w h ic h will
b
e more
fully
ex
plained
late
r ,
t
he
signal may be ap p lie d to
t
he V ertical Am p lifier from
t
he
Display D/
Α
an d Am p lifier
circuit alo n g wit h alp h anumeric
rea
d
out signals to
produce t he r e qu i r e d ve r tical deflection fo r
d is p lay of
sto r ed wavefor m s and r eado u t cha r acte r s .
H o r izontal signals fo r t he c rt d
is p lay a r e conn ected to t h e
H orizontal C h annel Switc h circ u
it
f r
om b ot h h orizontal
p
lug-in compartments . T h e H
O
R IZO N TA
L M OD E switc h
determi n es w h
et
h
er t h e signals f r om t he Α H
O
R
IZ o r Β
H O R IZ units a r e d is played by
t h e crt . H e r e, as in t
he
ve r tical system, t h e signal p at h
is sp lit into an a n alog and
αd igital p at h . Fo r t he analog p at h ,
t
he selected ho
r izo n tal
signal(s)
are a m plifie d by t he Ho r izo n tal A
m plifie r ci r cu it
w h
ic
h p
rovi d es ho r izo n tal d eflection
to t
he
crt . Th e
H o r izontal P ic k off am p lifie r converts
t h e push-pull
signals
fro m t he H orizontal C ha nn el Switc hto
t he single-
e nd ed signal r
eq u
i
r ed by t he H o r izo n tal Sam p
ler circ u it .
After signal
processi
n g simila
r to t h at of t he ve r
tical
system, store d wavefor m
a nd al phan u me r ic r ead
o
u t
d eflection sig n als m ay be a pp lie d
to t he H o r izo n tal
am p lifie r by t he Dis p lay D/ Α an d Am p lifier
ci r cuit w hen α
dis p lay of t hat ty pe is r e q u ired .
Th e R ea d o u t Ac qu i r e ci r
cuit
and
t h e Display D/ Α an d
Am p lifier ci r cuit pr ovi de an
al phan u me r ic dis p lay of
information enco d e d by t h e p lug-i n
units . T h e r ea d out
d is p lay is w r itten on t he c rt
on α ti
m
e-s h are d b asis wit h
the an alog or stored wavefo r m d is p lay . Th e
fro n t- pan el
M od e switc h es and t h e M ic r o p
rocessor ci r c u its
d ete r min e w h ic h pl u g-in units d isplay
r ea d o u t
i nfo r matio n .
T h e i nte rn al t r igge r signals fr om t he
vertical plug-i n un its
a
r
e connecte d to t he Α a nd Β Trigge r
Selecto r ci r cuits .
T h e M ode
Switc h andT r igge r Selector circ
u its d i r ect
t r igger signals f r om t he L
EFT V ERT o r R IG HT V ER T u
nits
to t h e Α H O R IZ o r ΒH
O
R IZ
units .
The M ai n fr ame
L ogic ci r cuit develo ps co n t r ol signals for
u se i n ot he r ci r cuits within
t h is inst r ume n t a nd t h ep l u g-
i n u nits . T h ese co n trol signals
au tomatically dete r m i ne
t he correct inst ru me n t ope r
atio
n i n
relation to t h e p l u g-i n
u nits, t he p lug-in u nit co n t r ol settings, a nd
t he 7854
co n t r ol settings .
T h e CRT Ci r cu it contains t he control ci r cuits n ecessary
fo
r
ope r atio n of t he crt . T h e Ζ -Axis Am p lifie r pr ovi des
t
he
drive signal
to co n tr ol t he i ntensity level of t he crt
display .
2-1

Figure 2-1 . Block Diagram
2-2

Figure 2-1 . Block
Diagram (continued)
2-3

The Calibrator
circuit produces α 1-kilohertz square-wave
signal which can be used to check t he calibration of this
instrument and t he compensation of probes . The
calibrator signal is available as α voltage at the
CALIBRATOR connector o r as αc urrent through α 40
milliampere optional current loop accessory .
The Output Signals circuit p rocesses signals from the
p lug-in u nits for
rear-panel output .
T
he Converter/Rectifiers and Low-Voltage R egulator
circuits
provide the p ower necessary to operate this
instrument . The voltages are connecte dto all circuits
within the instrument . The crt circuit contains αh igh-
voltage p ower supply that p rovides accelerating potential
for the crt .
The Auxilliary
R egulator circuit r egulates existing supply
voltages down to
the p otentials r equired by the digital
portion of this instrument .
The Front P anel Controls
circuit p rovides for user control
and a d justment of
crt beam and r eadout intensity as well
as other
functions such as trace F OCUS and trace
BEAMFINDER .
The Front Panel
K eyboard circuit provides user control of
the
functions p erformed by the microprocessor in t his
instrument
. P ushbutton switches on the front p anel
provi de this u ser-to-machine interface . The external
Calculator Keyboard is similar to the
Front P anel
K eyboard in that it p rovides user
i nterface
to
the
instrument microprocessor t
hrough α pushbutton
keyboard . This
k eyboard must be connecte d to the
instrument
through t he R ear Panel Connector circuit
which also p
rovides GPIB interface connectors for this
instrument .
The K eyboard
I nterface an d Signature Analysis circuit
p rovides
the electrical scanning necessary for the
reading of the above mentioned keyboards . It also
generates the signature analyzer clock a nd the
associated control levels
required
to use α
signature
analysis syste m for
troubleshooting this instrument .
The M other
Board p rovides the majority of
interconnection within t he d igital p ortion of this
instrument . U p to seven individual b oards
controlling
various operations of the 7854
m
ay
bep lugged i nto the
M other B oar d .
The
M icroprocessor and Control circuit is the control
center
of the d igital portion of this instrument . All
n
umerical an dwaveform manipulationas well as data
storage
and d isplay are either performed o r controlle d
d
irectly or in d irectly by this circuit .
The R
eadout Acquire circuit "rea d s" the step-analog
p lug-in data, r epresenting vertical d eflection factors,
h orizontal sweep rate, etc ., and e ncodes it into αd igital
format . This d igitial information is later processed and
results in α crt d isplay of one or more
alphanumeric
characters representative of
the p lug-in(s) setup
con d itions .
T he V ertical and Horizontal Sampler circuit samples,
stores, and buffers,
instantaneous analog voltage levels
fro m t he V
ertical and Horizontal P ickoff Amplifier circuits
to the Digitizer
so they may later be d isplayed on the crt .
These
samples, when displayed with other similar
samples,
represent α waveform derive d over one or more
crt sweep intervals .
The
Digitizer circuit accepts the buffered analog voltage
levels from t he V ertical an d H orizontal Sampler circuit
and converts them to ten-bit d igital words . The Digitizer
Control Logic circuit, in conjunction with t he Address
Generator circuit, generates the addresses n ecessary to
store this data for later use . It also generates the control
levels necessary for t he d igitizer syste m to request and
assume control of instrume n t busses to facilitate this
storage . Α special burst clock is r equire dby the d igitizer
syste m w hen d igitizing an d is p ro d uced by the Digitizer
Clock
circuit . As the d igitizer system d igitizes α
waveform, the Digitizer Sweep Counter detects when α
complete sweep has occure d . After α complete sweep
has been d etected, the micro p rocessor d etermines when
the digitizer system h as acquired e nough points to
ad equately represent the waveform being d igitized,
depending on the resolution (points per waveform)
desired .
The DMA Control circuit generates the timing sequence
an d co n trol levels necessary for DMA (direct m emory
access) d evices internal to the 7854 to take control of the
instrument busses .
TheGPIB
(general purpose interface bus) circuit allows
the 7854
Oscilloscope to b e used i n m ultiple instrument
GPIB configurations . This circuit
provi d
es
the
co m munications and control interface
necessary to GPIB
o peration .
The R OM and
RAM
circuits
provide the p ermanent and
temporary memory
required for proper operation of this
instrument .
Together, the V ertical and
Horizontal Display and Control
circuits provi de
the proper control voltages for operation
of oscilloscope
d eflection an d Ζ -Axis Amplifier circuitry
when displaying d igitally p rocessed waveforms or
characters . The Display D/ Α and A mplifier circuit
converts the stored dig ; tal d ata r epresenting waveform or
character information t~, analog voltage
levels
to
facilitate
vertical an d ho izontal 'eflection of
the crt b eam .

DETAILED CIRCUIT
OPERATION
T h is p ortion of t he Th eo
r y
of O p e
r
ation section
pr ovi
d es αd etailed d escri p tion of t h e elect r ical ope r atio na nd r elatio nsh i p
of t he circ u its
i n
t
he
7854
. T he t h eory
of op
eratio n
fo
r
ci r cu its u n i q ue to t h is instrument is desc r i b ed i n d etail i n t h is
discussio n . Circ u its co
mm only
u se
d in
t
he elect r
onics
i
n du stry a r e n ot d escribed in detail .
Th e following circ u it analysis is accom pan ie dby sup
p orting illustratio n s t h at give t he names of t he in d ivi dual
stages
with in
t he ma j o r ci r cu its, a nd sh ow h ow t h ey a r
e
co nn ected
toget he r to for m t h e ma j or circ u it . T h ese illustrations also sh ow t he
in pu ts an d outputs for eac h circ u it and t he r elations h ip of
t he f r o n t- panel con trols to t he i nd ivi du al stages . T he detailed
circuit d iagrams from w h ic hthe illustrations a r ede r ive d a r e sh own
in t he Diag r a m s section .
TEKTRONIX D R AF TI NG CO NVE NT IO N
At Te k tronix, logic sym b ols on sch ematics are d rawn
acco rd ing to t he function pe r for m e d by t h e d evice in its
partic u la r a pp lication . By so d oing, some d eviations from
t he ma nu fact ur er's assig ne d sym b ology occu r (alt h o ugh
device elect r ical fun ctio n is ide
n
tical) . An exam p le of t h is
wo u
l
d be an
A ND gate
(all
i n puts
Hl- -output HI ; any i npu t
LO---outpu t L O) d r awn as an O R gate fo r L Os (any in p u t
L O-- . -outp u t L O ; all in
puts
N 1--output HI) . T he first gate
s h own
in
Table
2-1
illustrates
t h is exa mp le a nd t he
r emai nd e r of t he ta b le f ur t he r ill u strates alternate
ways
of r ep rese n ti ng common logic gates . Th is ta b
le is
mea n
t
only to familia r ize t he reader wit h Te k t r onix d r afti ng
co n vention and not as α complete sou r ce of alter nate
sy mb ols used i n sch ematic d r afting . F o r ope r ational
c h a r acte r istics of i nd ivi du al d evices, r efe r to t he
ma nu fact ur e r 's data b oo k .
Diagram 1,
in
t
h
e
Diag r a m
s a nd Ci
rc u
it B oar d
Illustratio ns sectio n , s h ows t h e i nte r -co nn
ections
b
etween ma
j
or
ci r cu its wit h i nthe
7854
.
MODE S W ITC H AND CALIBRATO R
The M ode
Switc h circ u it im p
lements t
he
f r on t- pan el
switc
h i ng a nd p r ovides t he n ecessa r y logic for
selectio n
of
ve r tical arid ho r izontal d eflection signals
fo
r
the crt
dis p lay . T he M ode Switc h circuit ope r ates in co njun ction
wit h t he M ainf r ame L ogic ci r cuit (diag r am 4) an d t he
M icro p
rocessor
a nd Co
n
t
r ol circuit
( d
iag r am
28) to
d evelo p cont r ol sig nals fo r u
se
i n ot her ci r cuits wit h i n
t h is i n
st
ru ment, and wit h in p l u g-i n un its i n stalle d in
t
he
p l u g-i n compa r tments
.
T he Calib r ator circuit provides voltage out pu ts of 40
millivolts, 0 .4 volt and 4 volts at t he CA L I BR ATO Ro u t pu t
connector . Α cu r rent output of 40 milliam pe r es is
availab le fr om t he CA L I BR ATO R with an op tional c urr ent
loop adapte r . Wh en t he c urr e n t loop ad apte r is u se d , t h e
CA L I BR ATOR switc h must be set to t he 4 V p ositio n .
Figure 2-2 sh ows αdetailed block d iagram
of t
he
M ode
Switc h an d Cali b rato r ci r cu its . Α sc h e m atic of t h ese
circuits is s
h own
on
d iagram 2, in
Section 7, Diagrams
and Circ
u it B oar d Illustrations
.
T he sch
ematic is d ivi d ed
by g r ay s h a d ed li n es se p a r ati n g t he circuitry into m
a j o r
stages . S ub - h ea d i n gs i n t h e followi n g d iscussion
u se
t h ese stage na m es to ai d in locating a nd i de n tifyi ng t h e
componentsan d portions of t he circ u it r y d escri bed .
M ODE S W ITC H
The M od e Switc hp r ovi d es user cont r ol of t he 7854
ve r tical a nd ho r izontal ch an n el selection .
U ser comman ds from t he front panel M OD E switc h
es, S1
a nd S2, a r e co n verted to B CD ( binary co d e dd ecimal) by
U
1
an d a
r
e t he
nbu
ffe r ed by U 61A . P l u g-in comman ds
fr
o
m t he plug-i ns are
se
n
se
d
by co m pa r ator ICs U51 and
U
52 .
Th
ese logic levels are buffe
r
e d by U 62 a ndU 61 Β . At
i n
te r vals of a pproximately 20 m s, t h e microprocessor
(diagram 28) p
ulls
t
h
e
F P
R (f
r
on t p a n el r ea d ) li n e at Ρ 63-
1
LO, enabling U 61 an d U 62, tra n sfer r i n g t he front-panel
2-5