CBS laboratories 4100 Manual

JANUARY 1974
/■
OPERATING AND MAINTENANCE INSTRUCTIONS
Models, 4100,4 11 0
FM Volumax
(^0U) l^y
L/J k lA-
/ \ 3>-2.7- 7 700
C7<23) TS7-/4 2 i
PROFESSIONAL PRODUCTS
CBS LABORATORIES
A Division of Columbia Broadcasting System, Inc.
Stamford, Connecticut 0 905

TABLE OF CONTENTS
Section
Title
P ge
i
2-1
2-1
2-1
2-4
2-7
1-1
1-1
1-2
1-2
1-5
1-5
1-6
4-1
4-1
4-3
4-5
4-6
4-8
4-9
3-1
3-1
3-1
3-4
3-4
INTRODUCTION
Gener l
Function l Description
Physic l Description
W rr nty
Service nd Rep ir
Specific tions
OPERATIONAL SET-UP
Gener l
Set-Up of Stereo FM Volum x Unit
Set-Up of Mon ur l FM Volum x Unit
Proof-of-Perform nce Me surements
MAINTENANCE
Gener l
Troubleshooting G in Meter Circuit
Troubleshooting Input Section (Bo rd A2 or A5)
Troubleshooting High Frequency Control Section
(Bo rd Al or A4)
Troubleshooting Output Section (Bo rd A2 or A5)
Troubleshooting AGC Section (Bo rd A3)
Test nd Adjustment Procedures
5-1
5-1
5-3
5-4
5-4
THEORY OF OPERATION
Gener l
Input Section (Bo rd A2 or A5)
AGC Amplifier (Bo rd A3)
High Frequency Processor (Bo rd Al or A4)
Output Section (Bo rd A2 or A5)
Power Supply (Bo rd A3)
INSTALLATION
Unp cking
Mech nic l Inst ll tion nd Oper tion Consider tions
Power Source
Electric l Connections
III
3-1
3-2
3-3
3-4
I
1-1
1-2
1-3
1-4
1-5
1-6
II
2-1
2-2
2-3
2-4
IV
4-1
4-2
4-3
4-4
4-5
4-6
V
5-1
5-2
5-3
5-4
5-5
5-6
5-7
5-5
5-5
5-9

TABLE OF CONTENTS (cont)
Section
P ge
Title
7-1/7-2
• VII
DRAWINGS
LIST OF ILLUSTRATIONS
Fig. No.
Title
P ge
1-3
1-4
1-4
1-4
3-0
3-1
FM Volum x Controls
5-0
5-1
ii
2-2
2-3
2-5
2-6
2-1
2-1
2-2
2-3
4-1
4-2
FM Volum x Autom tic Pe k Controller
Are of Potenti l FM Overmodul tion (75-ps
Pre-Emph sis Curve)
Di gr m nd Oscilloscope Photos Showing Audio
Pe k Levels of Cymb l Cl sh with nd with 
out Pre- Emph sis
Simplified Block Di gr m, FM Volum x Model 4100
Outline Dr wing (Sheet 1 of 2 Sheets)
Outline Dr wing (Sheet 2 of 2 Sheets)
Typic l FM Volum x Inst ll tion Block Di gr m
Typic l Attenu tor for FM Volum x Input Line
(Schem tic Di gr m)
FM Volum x Block Di gr m
FM Volum x Amplitude Response
Loc tions of Circuit Bo rds nd Ch ssis P rts in
FM Volum x Unit
1-1
1-3
4-0
4-4
1-1
1-2
PARTS LISTS
Gener l
Resistors
Diodes nd Tr nsistors
M nuf cturers' N me Abbrevi tions
M in Assembly (Model 4110 or 4100)
High Frequency Processor Bo rd Al nd A4
Input-Output Bo rd A2 nd A 5
Power Supply nd AGC Bo rd A3
Front P nel Assembly A6 (Model 4110 or 4100)
VI
6-1
6-2
6-3
6-4
6-5
6-6
6-7
6-8
6-9
6-1
6-1
6-1
6-1
6-2
6-3
6-4
6-7
6-10
6-13

LIST OF ILLUSTRATIONS (cont)
Title
Fig. No-
P ge
7-7/7-8
7-3
7-9/7-10
7-4
LIST OF TABLES
T ble No. Title P ge
iii
5-2
5-3
5-4
5-1
5-2
5-3
7-1
7-2
FM Volum x, Intern l Interconnections
High Frequency Processor Bo rd Al or A4,
Schem tic nd P rts Loc tion Di gr ms
Input-Output Bo rd A2 or A5, Schem tic nd
P rts Loc tion Di gr ms
Power Supply-AGC Bo rd A3, Schem tic nd
P rts Loc tion Di gr ms
Complete Test Setup for Mon ur l Model 4100
Complete Test Setup for Stereo Model 4110
Att ck Time Test W veform
Power Supply Volt ges
Typic l Volt ges
FM Volum x M inten nce Tests nd Adjustments
5-27
5-28
5-29
7-3/7-4
7-5/7-6
5-7
5-7
5-11

SECTION I
INTRODUCTION
1-1.
GENERAL
This m nu l provides instructions for the CBS L bor tories Model 4100
trollers.
These instruments h ve been designed for use in FM nd TV bro dc st 
ing pplic tions in which the use of pre-emph sis is m nd tory. Either
instrument will en ble the full modul tion c p bility of the tr nsmitter to be
utilized with no risk of overmodul tion.
It repl ces ny limiter or clipper th t
m y now be in use. When used with SCA** systems, it prevents crosst lk
c used by overmodul tion from entering into dj cent ch nnels.
It should be
oper ted with well-controlled udio input levels such s provided by the CBS
L bor tories Audim x* utom tic level control.
a
s
• q *
C®'
Figure 1-1.
FM Volum x Autom tic Pe k Controller
1-1
FM VOLUMAX
*
**
CBS L bor tories Tr dem rk
Subc rrier Authoriz tion
(Mon ur l) nd Model 4110 (Stereo) FM Volum x* utom tic udio pe k con-

INTRODUCTION
1-2. FUNCTIONAL DESCRIPTION
The Models 4100 nd 4110 re l te designs b sed on the found tion
est blished in the e rlier Model 410 FM Volum x unit. They extend the
origin l technology to yield cle ner, brighter sound while still ret ining
bsolute protection g inst overmodul tion.
A very f mili r problem in FM nd TV bro dc sting is c used by the
m nd tory 75-ps pre-emph sis curve (fig. 1-2).
This is long est blished
requirement of the FCC for the improvement of the over ll sign l-to-noise r tio.
At the time the FM nd TV bro dc sting st nd rds were dopted, the long-term
ver ge spectr l distribution of music sign ls showed ste dy decline with
frequency bove 1, 000 Hz. This me nt th t high-frequency pre-emph sis with
subsequent de-emph sis t the receiver could be employed to improve the over 
ch nges in recording techniques in conjunction with soci l ch nges in music l
style h ve led to incre sing problems with the overmodul tion c used by high-
mplitude high-frequency progr m sign ls.
The FM Volum x unit solves this problem uniquely by qu druple- ction
independently processed nd over ll, inst nt neous, fin l limiting is used to
PHYSICAL DESCRIPTION
1-3.
The Models 4100 nd 4110 FM Volum x units re housed in the s me new
slimline p ck ges s the CBS L bor tories Audim x nd AM Volum x units.
1-2
ssure th t no overmodul tion will occur. See lso figures 1-3 nd 1-4.
ll sign l-to-noise r tio. However, in recent ye rs, improvements nd other
control. Low-, middle-, nd high-frequency portions of the progr m w ve re

INTRODUCTION
MODULATION
18
800%
16
14
400%
12
200%
4
2
0
100%
20
20000
1-3
i
5
I
2
I
5
I
2
1
5
Figure 1-2. Are of Potenti l FM Over 
modul tion (75-ps Pre-Emph sis
Curve)
i 11
100
i 11
10
I 11
1000
10
db
8

INTRODUCTION
9dB
pre-emphasis
OdB
bove 5KHz
below 5KHz
>
1-4
Figure 1-3. Di gr m nd Oscilloscope Photos
Showing Audio Pe k Levels of Cymb l
Cl sh with nd without Pre-Emph sis
Figure 1-4. Simplified Block Di gr m, FM Volum x
Model 4100
active
filters
high
frequency
processor
Summation
Network
low
frequency
control
pre 
emphasis
dynamic
i frequency
compensator
final
limiting

INTRODUCTION
This p ck ge requires only 1-3/4 inches of height in st nd rd 19-inch r ck
circuitry is function lly p ck ged on three circuit bo rds in the mon ur l
re equipped with ppropri te test points to speed the process of m inten nce
tests or troubleshooting procedures.
The entire unit slides forw rd on r ck slides for e sy servicing without
disconnections from the tr nsmitting system. Front p nel controls re
conveniently rr nged nd, in the stereo unit, re grouped ccording to ch nnel--
left ch nnel controls on the left of the unit nd right ch nnel controls on the
right of the unit. A front p nel meter indic tes the rel tive degree of g in re 
duction.
The unit c n be oper ted from either 115-volt or 230-volt single-ph se
50- or 60-Hz power source. On delivery, the unit is wired for 115-volt oper -
Wiring ch nges for 230-volt oper tion re expl ined in p r gr ph 2-3.
tion.
1-4. WARRANTY
A st nd rd w rr nty c rd h s been included with your FM Volum x unit.
To v lid te your w rr nty, complete nd return the postc rd section to CBS
L bor tories s soon s possible.
SERVICE AND REPAIR
1-5.
If there is difficulty in oper ting or m int ining your FM Volum x unit,
c ll on your loc l uthorized distributor from whom you origin lly purch sed the
1-5
unit. If you do not know the n me nd ddress of your loc l distributor, c ll
FM Volum x model nd on five circuit bo rds in the stereo model. Both models
nd 18-1/2 inches of depth behind the front p nel. The reli ble solid-st te

INTRODUCTION
CBS L bor tories, Profession l Products Dep rtment, St mford, Conn.,
06905, telephone [phone].
1-6. SPECIFICATIONS
Input imped nce
Output imped nce
-22 dBm to +8 dBm
Input level
25 dBm
M ximum output level
Frequency response
H rmonic distortion
Att ck time
Recovery time
Sign l-to-noise r tio
Gre ter th n 70 dB
Within 1/2 dB
Amplitude
Ph se
Within 1. 5 degrees
+55°C (+130°F)
1-6
Tr cking ccur cy
(stereo model):
M ximum oper ting
temper ture
±1 dB, 50 - 15, 000 Hz below limiting
threshold. V ri ble s function of
level bove limiting threshold, re ching
the 75-p.s de-emph sis ch r cteristic
±1 dB t m ximum level
600 ohms, b l nced or unb l nced; 10
kilohms or 150 ohms v il ble on
request
Between 1 qs nd 2 ms, depending on
progr m w veform
200 ms (low frequencies)
5 ms (middle frequencies)
1 qs or less (high frequencies)
600 ohms, flo ting or single ended;
150 ohms v il ble on request
Less th n 1%, below threshold of limiting,
50 - 15, 000 Hz

INTRODUCTION
Power requirements :
Dimensions
Shipping weight:
Mon ur l model
13 pounds
14 pounds
Stereo model
1-7
1-3/4 inches high, 18-1/2 inches
deep; fits st nd rd 19-inch r ck
with univers l hole sp cing
12 w tts, 115/230 v c, 50/60 Hz
(mon ur l)
15 w tts, 115/230 v c, 50/60 Hz
(stereo)

SECTION II
INSTALLATION
2-1.
UNPACKING
C refully unp ck your FM Volum x unit nd ex mine it for evidence of
cl im immedi tely with the tr nsport tion c rrier. If future tr nsport tion of
the unit c n be expected, s ve the shipping c rton for re-use.
MECHANICAL INSTALLATION AND OPERATIONAL CONSIDERATIONS
2-2.
The FM Volum x unit is shipped with p ir of r ck slides which help to
ensure st ble mounting in the r ck nd permit e sy ccess to the intern l
p rts of the unit if servicing should be necess ry. A me ns of mounting the
slides to the r ck is det iled in figure 2-1.
The unit nd its slides re designed to be mounted in st nd rd 19-inch
electronic equipment r ck with univers l hole sp cing. The front p nel requires
1-3/4 inches of sp ce in the height dimension, nd 18-1/2 inches of depth behind
the front p nel re needed for the ch ssis. As for ll tr nsistor equipment,
the unit must be inst lled in re son bly well ventil ted position with no high-
he t-producing equipment bene th it.
CAUTION
The mbient temper ture should not
exceed 130°F (55°C).
Telco line is used to link the stu'dio nd tr nsmitter sites, the FM Volum x unit
is norm lly inst lled t the tr nsmitter site, immedi tely before the udio input
2-1
Figure 2-2 is block di gr m of recommended inst ll tion. When
d m ge th t m y h ve occurred in shipment. In the event of d m ge, file

INSTALLATION
I
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CBS LAQQUKTOMiey
2-2
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Figure 2-1. Outline Dr wing (Sheet 1
of 2 Sheets)
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INSTALLATION
2-3
RACK
DRILL OUT TAPPED HOLES IN RACK TO
ACCOMMODATE USE OF MOUNTING PLATE.
Figure 2-1. Outline Dr wing (Sheet 2
of 2 Sheets)
MOUNTING PLATE
(SUPPLIED WITH SLIDE)
To i
JI
I I
i :
i ,

INSTALLATION
termin ls of the tr nsmitter. The FM Volum x unit h s sufficient g in to
correct for long-line nd equ lizer losses. However, if pre-emph sized
microw ve STL* is used, the FM Volum x unit should precede the STL
tr nsmitter.
It should be remembered th t the function of the FM Volum x unit is
for progr m line. Optimum oper tion will be obt ined when the FM Volum x
unit is supplied with uniform input levels such s those produced by the CBS
L bor tories Audim x unit or other high-qu lity utom tic g in control.
Input levels s low s -24 dBm c n be ccommod ted. If high input
levels re used -- s will be the c se when n FM Volum x unit is connected
"H" shown in figure 2-3 should be inserted immedi tely he d of the FM
Volum x unit.
2-3.
POWER SOURCE
The FM Volum x unit is equipped with power tr nsformer which
for 115 v c oper tion. If 230 v c oper tion is desired, m ke the following
modific tions t the intern l termin l strip TB1 t the re r of the unit next to
the re r p nel.
Remove the bl ck/white le d from termin l 4 of TB1.
A.
Remove the brown nd white le ds from termin l 5 of TB1.
B.
* Studio-Tr nsmitter Link.
2-4
permits either 115 v c or 230 v c oper tion. As delivered, the unit is wired
immedi tely fter n Audim x unit -- fixed ttenu tor p d such s the "T" or
th t of pe k protection; this unit should not be used s "g in riding" device

EQUALIZED LINE
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FM VOLUMAX FM TRANSMITTER
AUDIMAX
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MONITOR,
ETC
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TELEPHONE
COMPANY
INTERFACE
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INSTALLATION
A/w
AAA
o
-o
430 OHMS
430 OHMS
o-
o
A. SYMMETRICAL "T" IGdB PAD, 000HMS IN/OUT
o- -o
AAV
AAV
■o
o
220 OHMS
220 OHMS
8. SYMMETRICAL " h " I d8 PAD, 00 OHMS IN/OUT
2-6
Figure 2-3. Typic l Attenu tor for FM Volum x
Input Line (Schem tic Di gr m)
— AAA, ------
220 OHMS
— AAA -----
220 OHMS
<200 OHMS
>200 OHMS

INSTALLATION
C.
D.
ELECTRICAL CONNECTIONS 2-4.
The 10-termin l strip TB2 t the re r of the ch ssis is used for ll
input nd output connections to the EM Volum x unit. Use pins 1 nd 2 for the
mon ur l oh left-ch nnel-stereo input nd pins 4 nd 5 for the corresponding
output. Simil rly, for the stereo model, use pins 6 nd 7 for the input to the
To m int in correct stereophonic ph sing (stereo model), the sign ls
t termin ls 1 nd 6 should be in ph se when mon ur l sign l is pplied.
Sign ls t termin ls 4 nd 9 will then lso be in ph se.
If the FM Volum x unit is termin ted with n unb l nced lo d, termin ls
4 nd 9 should be used s the "high"-side termin ls, nd termin ls 5 nd 10
should be used for the common connections.
The st nd rd FM Volum x unit is wired for 600-ohm oper tion. If 150-
In ny c se, termin te outputs
ohm oper tion is desired, consult the f ctory.
in their ch r cteristic imped nces.
Input imped nce m y be converted to 150 ohms by ch nging A2R5 ( nd
A5R5 in the stereo model) to 150 ohms.
2-7
, Connect the brown, white, nd bl ck/white le ds together
nd sleeve the connection.
Repl ce the origin l fuse with type 3AG-0. 15 mp
(SLO-BLO).
right ch nnel nd pins 9 nd 10 for the right-ch nnel output. Pins 3 nd 8 re
ch ssis grounds .

OPERATIONAL SET-UP
aa
INPUT
OUTPUT
Figure 3-1. FM Volum x Controls
3-0
CB^LABO ha TOHE3
c
a
n
GAIN
REDUCTION
METER
TEST
SWITCH
a
a
RIGHT CHANNEL
LEVEL CONTROLS
(MODEL 4110 ONLY)
a a
i a & ' v
POWER POWER , INPUT OUTPUT ,
SWITCH INDICATOR -------------- J- --------- '
LEFT CHANNEL
OR MONOPHONIC
LEVEL CONTROLS
XL
u u
u u u
u
u
a a
g a
a a
a a

SECTION III
OPERATIONAL SET-UP
GENERAL
3-1.
All of the necess ry oper tion l controls re loc ted on the front of the
output controls for the left ch nnel re loc ted t the left of the meter nd input
nd output controls for the right ch nnel re loc ted t the right of the meter.
In the mon ur l version, ll controls re loc ted t the left of the meter, nd,
in either model, the power switch is loc ted t the extreme left end of the front
p nel. A switch to control n intern l bro d-b nd limiter is loc ted on the left
side of the front p nel in either model. The g in reduction meter in the center
of the p nel me sures the mount of bro d-b nd g in reduction nd should be
used s gener l guide in djusting the input level controls.
SET-UP OF STEREO FM VOLUMAX UNIT 3-2.
After ll electric l connections h ve been m de s in Section II, A.
POWER switch up. Le ve the TEST switch down.
Apply 400-Hz left ch nnel sine-w ve t norm l reference level B.
REDUCTION meter deflection to the red/green junction.
Move the TEST switch up to the TEST position nd turn the left
C.
OUTPUT level control clockwise s f r s necess ry to produce the m ximum
This step provides precise setting of the
desired left ch nnel modul tion.
3-1
to the FM Volum x unit. Adjust the left INPUT level control for GAIN
FM Volum x unit s shown in Figure 3-1. In the stereo version, input nd
turn the INPUT nd OUTPUT level controls fully counterclockwise. Be sure
both outputs re termin ted in their ch r cteristic imped nces. Push the