Digital Equipment VT100 Operating manual

VTlOO
MINI
MAINTENANCE
· HARDWARE GUIDE

EK-VT100-J1-001
VT100 Mini Maintenance
Hardware Guide.
digital equipment corporation • maynard, massachusetts

1st Edition. September 197a
Copyright~ 1978 by Digital Equipment Corporation
The material in this manual is for informational purposes and is subject
to change without notice.
Digital Equipment Corporation assumes no responsibility for any errors
which may appear in this manual.
Printed in U.S.A.
This document was set on DIGITAL's DECset-8000 computerized
typesetting system.
The following are trademarks of Digital Equipment Corporation.
Maynard. Massachusetts:
DEC
DECCOMM
DECsystem-10
DECSYSTEM-20
DECtape
DEC US
DIGITAL
MASSBUS
PDP
RSTS
TYPESET-8
TYPESET-11
UNIBUS
CONTENTS.
CHAPTER 1
TROUBLESHOOTING
1.1 TROUBLESHOOTING WITH THE
SELF-TEST FEATURES.......................................1-1
1.2 TROUBLESHOOTING THE BASIC
TERMINAL..............................................................1-1
1.3 TROUBLESHOOTING THE OPTIONS..............1-1
1.4 RECOMMENDED SPARES LIST(RSL)......... 1-10
2.1
2.1.1
2.1.2
2.1.3
2.1.4
2.1.5
2.1.6
2.1.7
3.1
3.1.1
. 3.,1.1.1
3.1.1.2
3.1.2
3.1.2.1
3.1.2.2
3.1.3
3.1.3.1
3.1.3.2
3.1.4
3.2
4.1
4.2
4.2.1
4.2.2
4.2.3
CHAPTER 2
OPERATING SUMMARY
SET-UP...................................................................2-1
SET-UP A........................................................ 2-.1
SET-UP B........................................................ 2-2
Changing a SET-UP Feature..................... ~ .. 2-4
Setting the Answerback Message ............... 2-4
Saving SET-UP Features.............................. 2-5
Recalling SET-UP Features.......................... 2-5
Resetting theTerminal................................... 2-5
CHAPTER 3
TESTING THE VT100
INTERNAL SELF TESTS ............_.......................3-1
Power-Up Test...............................................3-1,
Description...............................................3-1
Performing the Test............-.................. 3-2
Data loopback Test ..................................., .. 3-.2
Description............................................... 3-2
Performing the Test................................ 3-2
Video Adjust Test..:........................................ 3-3
Description............................................... 3-3
Performing the Test .. _.., ....... -................ 3-3
Error Codes...........................;.......................... 3-3
USE OF THE PMK04 TESTER ........._................ 3-4
CHAPTER 4
VIDEO ALIGNMENT
GENERAL..............................................................4-1
MONITOR ADJUSTMENTS............................... 4~1
Brightness.......................................................4-1
Focus ............................................................... 4-2
·Yoke.................:........................:....................... 4-2
4.2.4 vertical Height ............................................... 4-4
4.2.5 Horizontal Width...................: .. :..................... 4-5
4.2.6 Centering......................................................... 4-6
4.2.7 Vertical Linearity............................................ 4-6
4.2.8 Horizontal Linearity....................................... 4-7
4.2.9 Vertical Hold......................,......:..................... 4-7
iii

5.1
5.2
5.3
5.4
5.5
5.6
5.7
5.8
5.9
5.10
5.11
5.12
5.13
5.14
5.15
5.16
5.16.1
CHAPTER 6
MODULE REMOVAL AND
REPLACEMENT
GENERAL..............................................................5-1
ACCESS COVER ...................................................5-1
TERMINAL CONTROLLER BOARD..................5-1
ADVANCED VIDEO BOARD..............................5-3
20 mA CURRENT LOOP BOARD......................5-4
KEYBOARD TOP COVER ....................................5-4
KEYBOARD...........................................................5-4
KEYBOARD CABLE............................................. 5-5
KEYBOARD SPEAKER........................................5-5
TOP COVER ...........................................................5-6
VIDEO MONITOR BOARD.................................5-6
FLYBACKTRANSFORMER ...............................5-8
BOTTOM COVER .........................................•.......5-9
POWER SUPPLY ..................................................5-9
DC POWER HARNESS..................................... 5-10
FIELD SERVICE CRT MONITOR
ASSEMBLY.........................................................5-11
CRT Storage and Disposal.........................5-12
CHAPTER 6
VT100 OPTIONS
6.1 GENERAL..............................................................6-1
6.2 ADVANCED VIDEO OPTION .............................6-1
6.2.1 Advanced Video Option
Installation......................................................6-1
6.2.2 Advanced Video Option Checkout..............6-1
6.3 20 mA CU ARENT LOOP OPTION.....................6-2
6.3.1 20 mA Current Loop Option
Installation......................................................6-2
6.3.2 20 mA Current Loop Option
Checkout......................................................... 6-4
CHAPTER 7
PHYSICAL/FUNCTIONAL BLOCK
DIAGRAM
FIGURES
2-1 SET-UP A Presentation.......................................2-1
2-2 SET-UP B Presentation ....................................... 2-2
2-3 SET-UP B Summary............................................2-3
4-1 Video Alignment Templates ............................... 4-3
4-2 Video Monitor Board Adjustments.................... 4-4
4-3 CRT Adjustments................................................. 4-4
5-1 Module Removal Sequence................................5-2
5-2 VT100Termina1View..........................................5-3
5-3 Terminal Control Board with Advanced
Video Option......................................................... 5-3
iv
5-4
5-5
5-6
5-7
5-8
5-9
5-10
6-1
6-2
1-1
1-2
1-3
1-4
2-1
3-1
3-2
Keyboard Disassembly........................................ 5-5
Cover Removal......................................................5-7
Video Monitor Board Removal...........................5-7
CRT Anode Discharging......................................5-8
Power Supply Removal .......................................5-9
Power Supply Capacitor Discharging............. 5-10
DC Power Harness Removal............................5-11
Advanced Video Option lnstallation..................6-2
Current Loop Option ............................................ 6-3
TABLES
Keyboard LED Error Codes ................................. 1-1
Display Error Codes..............................................1-2
Basic VT100 Troubleshooting Procedure........ 1-4
Recommended Spares......................................1-10
SET-UP Feature Change Summary................... 2-4
LED Error Codes ...................................................3-3
Displayed Error Codes ......................................... 3-4
v

CHAPTER 1
TROUBLESHOOTING
1.1 TROUBLESHOOTING WITH THE SELF-TEST FEATURES
The VT100 contains a series of internal self-tests designed toisolate
a failure to a field replaceab1e unit (FRU). Tables 1-1 and 1-2 showthe
errorcodes. the detected failure. and the FRU which should be replaced.
Table 1-1 Keyboard LED Error Codes
Keyboard LEDs Error Detected Replace FRU
L1 L2
L3
L4
OFF OFF OFF ON ROM1 Terminal Controller
OFF OFF ON OFF ROM2 Terminal Controller
OFF OFF ON ON ROM3 Terminal Controller
OFF ON OFF OFF ROM4 Terminal Controller
OFF ON OFF ON Main Data RAM Terminal Controller
1.2 TROUBLESHOOTING THE BASIC TERMINAL
Table 1-3 lists the .most common VT100 failures and associated
symptoms. To use this table simply select the symptom that matches
the terminal failure.
1.3 TROUBLESHOOTING THE OPTIONS
Troubleshooting the terminal options should be performed after the
basic terminal is checked and found to be good. Once this is done.
perform the option checkout procedure for the suspected faulty option
as outlined in Chapter 6. If the option does not check out correctly.
replace the option module.
1-1

Table 1-2 Display Error Codes
Error Detected
Error
Character
Advanced
Nonvolatile
Date
Displayed
Video
RAM
Keyboard
Loopback EIA Replace
1 x Advanced Video
2 x Terminal Controller
3 x x Advanced Video and··
Terminal Controller
4 x Keyboard
5 x x Advanced Video and ·
Keyboard
6 x x Terminal Controller
and Keyboard
7 x x
x:
Advanced Video. Terminal
Controller and Keyboard
8 x -Terminal Controller
9 x x Advanced Video and
Terminal Controller
: x
-·
x Terminal Controller
; x x x Terminal Controller and
Advanced Video
> x x Keyboard and Terminal
Controller
= x x x Advanced Video. Keyboard and
Terminal Controller
I
1
< x x x Terminal Controller
and Keyboard
x x x x Advanced Video. Keyboard and
Terminal Controller
@ x Terminal Controller
A x x Advanced Video and
Terminal Controller
B x x Terminal Controller
c x x x Advanced Video and
Terminal Controller
D x x Keyboard and
Terminal Controller
E x x x Advanced Video. Keyboard and
Terminal Controller
-F x x x Keyboard and Terminal Controller
w G x x x x Advanced Video, Keyboard and
Terminal Controller
H x x Terminal Controller
x x x Advanced Video and
Terminal Controller
J x x x Terminal Controller
K
x.
x x x Advanced Video and
Terminal Controller
L x x x Keyboard and
Ter_minal Controller
M x x x x Advanced Video. Keyboard
and
Terminal Controller
N x x x x Keyboard and Terminal Controller
0 x x x x x Advanced Video. Keyboard and
Terminal Controller

Table 1-3 Basic VT100 Troubleshooting Procedure
General notes on using the basic terminal troubleshooting chart:
1. This chart assumes that only one field replaceable unit (FRU) has 2. Spare parts do fail. The possibility of a failure should not be dis-
failed. The symptoms displayed may be representative of a multiple counted just because the module has been replaced once.
failure. and as a result. the symptoms may change as FRUs are 3. Power must be turned off before any of the FRUs are disconnected
replaced. Always troubleshoot according to the current symptoms. or replaced.
Symptoms
No response when the power switch is set to
the on position. The CRT filament is not lit
and LEDs are not on.
No response when power switch is set to the
on position and the CRT filament is lit.
There are no audible tones when the terminal
is turned on. LEDs are lit.
There are no audible tones when the terminal
is turned on and none of the keyboard LEDs
are lit.
Cursor does not appear on the screen after
the terminal is powered up. The CRT filament
is turned on.
Probable Cause
Not plugged in; no power at wall socket.
Main power fuse
Power supply
AC line cord
Power distribution harness
Power Supply
Terminal controller board
Power distribution
Keyboard
Keyboard cable
Controller ·
Speaker
Keyboard disconnected
Keyboard cable
Keyboard
Controller
Connectors
Screen brightness too low
Controller
Monitor Board
Flyback transformer
DC power harness
F.S. monitor assembly
I
Corrective Action
Plug in VT100; use different wall socket if
possible.
Replace fuse (iffuse blows again there is a
possible shorting problem).
Replace power supply.
Check for open or short and replace line cord
Replace harness.
Replace power supply.
Replace board.
Replace harness
Replace.
Replace.
Replace.
Replace.
Connect.
Replace.
Replace.
Replace.
Check and reconnect.
Adjust monitor brightness (Paragraph 4.2.1),
Replace.
Replace.
Replace.
Replace.
Replace.

Table 1-3 Basic VT100 Troubleshooting Procedure (Cont)
Symptoms
Cursor does not appear on the screen after
the terminal is powered up. CRT filament is
not on. Keyboard is functional.
Random characters appear on the screen.
(,, A horizontal or vertical line appears on the
screen.
Screen display is distorted. Characters are
narrow on the left or right side of the screen.
The display presentation bows in or out.
Screen display is jumpy
The wrong character appears on the screen
when typed in LOCAL mode.
The wrong character appears on the screen
when typed in the ON-LINE mode with
loopback installed. Terminal functional in
LOCAL mode.
Probable Cause
Monitor fuse open
Monitor wiring
DC power harness
F.S. monitor assembly
Controller
Monitor connectors
Monitor board
F.S. monitor assembly
Monitor is misadjusted
Monitor board
Flyback transformer
F.S. monitor assembly
Controller
Yoke pincushion misadjusted
Interlace feature on
Wrong power feature set
Controller
Power supply
Monitor board
Flyback transformer
Graphics. or alternate character set. or
alternate keypad mode. or cursor key mode is
selected.
Keyboard
Controller
Graphics. or alternate character set, or
alternate keypad mode. or cursor key mode is
selected.
Transmit and receive speed not the same·
Controller
Corrective Action
Replace monitor board.
Replace monitor board.
Replace.
Replace.
Replace.
Check and reconnect.
Replace.
Replace.
Adjust monitor (Chapter 4).
Replace.
Replace.
Replace.
Replace.
Replace ~.S. monitor assembly.
Turn feature off.
-·--
Set feature to correct Iine frequency.
Replace.
Replace.
Replace.
Replace.
Clear condition with power up or RESET
Replace.
Replace.
Clear conditions with power up or RESET.
Change spe~d setting.
Replace.

....
cio
Table 1-3 Basic VT100 Troubleshooting Procedure (Cont)
Symptoms
The wrong characters appear on the screen
when typed in the ON-LINE mode and
connected to computer. Terminal is
functional with loopback connector.
Messages received are incomplete
Checkerboard character appears on screen
instead of character typed (on-line with
computer).
All characters displayed as a white area
(black with reverse screen).
Only top or bottom half of characters are
displayed on tile screen.
The S.ET-UP features do not work correctly
(multiple alarms may sound on power up or
recall).
·The terminal does not respond to escape
sequences.
Probable Cause
Receive and/or transmit speed setincorrectly
Bits per character feature set incorrectly.
Parity feature set incorrectly
Communications line
XON/OFF feature set incorrectly
Computerdoes not recognize XON/OFF
sequence
Controller
Parity feature set incorrectly
Controller
Communication facility problem
Alternate character set selected and not
available.
Incorrect use of double height escape
sequence
Save operation not performed.
Controller
Power supply
ANSl/VT52 feature set incorrectly
I
Corrective Action
Set speeds to match computer.
Set feature to match computer.
Set parity and/or parity sense feature to
match computer.
Check communication facilities.
Set feature.
See Chapter 3 of VT100 User's Guide.
Replace.
Set parity and/or parity sense feature to
match computer.
Replace.
Check communication facility.
Clear condition with power up or RESET.
See Chapter 3 of VT100 User's Guide.
Perform Save operation.
Repla<'.e controller.
Replace power supply.
Set ANSllVT52 feature to correct
compability.

1.4 RECOMMENDED SPARES LIST (RSL)
Table 1 -4 lists the recommended spares for the Basic VT100.
Included in this list are spares for the Advanced Video Option and the
20 mA Current Loop Adapter Option.
Quantity
10
1
1
2
5
5
5
15
15
5
15
15
5
15
5
5
5
5
Table 1-4 Recommended Spares
Description
Monitor printed circuit board
Terminal controller PCB
Advanced Video PCB
20 mA Adapter assembly
20 mA Interface cable (15 ft)
EIA cable (M-FI ( 10 ft)
EIA cable (null modem)
LK keyboard
Cable assembly, keyboard
Speaker
LK07 keycap set
LK08 keycap set
Keycap removal tool
Power supply assembly
Power switch
Voltage select switch. 110 V/220 V
Fuse. 3 A
line cord. 115 V
line cord. 230 V
DC power distribution cable
Card guide
Retainer ring•
Support. chassis•
Cable clamp•
Plunger, chassis mounting•
Grommet. chassis•
Captive screw•
Plunger, base mounting•
Plunger, base mounting•
Standoff. AVO•
Grommet. base•
Mounting screw•
Feet•
Fuse holder•
Screw. #6-20 X 1/2. hex head
Screw. #6-32 X 5/16
CRT mask. alignment
Shaft extender
Alignment tool. monitor·
Kit. carrying case
l.C. container
loopback connector. RS232C
loopback connector. 20 mA
Flyback transformer. Ball monitor
F.S. monitor assy, Ball monitor t
I Part Number
30-14590-02
54-13009
54-13097
70-15273
. BC05F-15
BC05D-10
BC03M-10
70-15765
70-14652
. 12-15050
12-14333- 72
12-14333-91
74-16355
70-14979
12-15232
12-14155-03
90-07217
170083-09
170083-10
70-14978
12-12405-00
90-10007
90-09747-01
90-1001 6-00
90-09964
90-09966-01
12-14811
12-14740-00
90-09965-00
90-09747-03
90-09966-00
12-14817
90-09624-00
12-12893
90-09680-04
90-09701-00
94-03220-03
29-23189-00
29-23190-00
29-23187
99-05812
12-15336
70-1 5503-00
30-14590-01
70-16187
·These items are expendable.
tThis assembly consists of the CRT. yoke. vertical coil. flyback trans-
former. video monitor board. and sheet metal enclosure.
1-10
2.1 SET-UP
CHAPTER 2
OPERATING SUMMARY
SET-UP mode is a special mode of operation that allows the user to:
1. Enable and disable the terminaI features
2. Enter and. store a 20-character answerback message
3. Save the selected features in a nonvolatile memory
4 .. Temporarily change the terminal features and then recall the original
settings.
To perform these functions SET-UP mode is divided into two display
presentations: SET-UP A and SET-UP B.
2.1.1 SET-UP A
To enter SET-UP A press the SET-UP key. The display will now have
a presentation similar to Figure 2-1. The bottom line of the display
consists of a ruler that numbers each character position available on a
line. The location of each tab stop is shown by a "T" placed above the
ruler.
SET-UP·A
TO·EXIT·PRESS·•SET-UP"
Figure 2-1 SET-UP A Presentation
2-1

In SET-UP A mode the following features may be changed:
TABS
BRIGHTNESS
CHARACTERS PER LINE
LINE/LOCAL
See Paragraph 2.1 .3 to change a feature.
2.1.2 SET-UP B
SET-UP B mode may only be entered from SET-UP A mode. To enter
SET-UP B from SET-UP A. press the 5 key on the main keyboard. The
display will have a presentation similar to Figure 2-2. Figure 2-3 sum-
marizes the SET-UP B presentation.
SET-UP B
TO EXIT PRESS "SET-up•
Figure 2-2 SET-UP B Presentation
2-2
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-1
2-3

2.1.3 Changing a SET-UP Feature
Table 2-1 summarizes the SET-UP features. indicates the SET-UP
mode required to change the feature. and shows the key used to change
the feature.
Table 2-1 SET-UP Feature Change Summary
SET-UP Feature
Changed In
Key Used To
SET-UP A
SET-UP B Change Feature
ANSWERBACK x t
ANSl/VT52
x Iii
AUTO REPEAT x [[!
AUTO XON/XOFF x
[[I
BITS PER CHARACTER x [[J
BRIGHTNESS x x
·mor[J
CHARACTERS PER LIN'E x !]]
CURSOR x [§]
INTERLACE x [§]
KEYCLICK x
I[§)
LINE/LOCAL x x
rn
MARGIN BELL x I]]
NEW LINE x·
~
PARITY x
[]]
PARITY SENSE x
[]]
POWER x [§]
RECEIVE SPEED x []J
SCREEN
x
I]]
SCROLL x I]!
TABS x
ffiandl!J
TRANSMIT SPEED x
l:ZI
WRAPAROUND x
(]]
# £ x 6
3 (shifted)
t A special sequence is required for this feature (Paragrlph 2.1.4).
2.1 .4 Setting the Answerbadc: Message
Use the following procedure to set the answerback message:·
1. Place the terminal in SET-UP B mode.
2. Press the SHIFT and A keys simultaneously. The terminal will
respond by placing A= on the screen. (The SHIFT key is required:
the CAPS LOCK key will not work here.)
3. Type the message delimiter character. which may be any character
not used in the actual answerback message. (The message delimiter
character is not a part of the answerback message.) If a mistake is
made while typing the answerback message. type the message de-
limiter character again and go back to step 2. This is the only way to
correct errors in the answerback message.
2-4
4. Type the answerback message, which may be up to 20 characters
long. including space characters. If the message exceeds 20 charac-
ters. the answerback message will disappear from the screen after
the 20th character is typed. In this case the message delimiter char-
acter described in the next step is not required.
5. Type the message delimiter character. which is only required when
the answerback message is less than 20 characters. Once the mes-
sage delimiter character is typed the answerback message will dis-
appear from the screen.
2.1 .5 Saving SET-UP Features
Use the following procedure to save the current SET-UP feature set-
tings in nonvolatile memory.
1. Place the terminal in SET-UP mode.
2. Press the SHIFT and S keys simultaneously. The screen will clear
and the message "Waif' will be displayed in the upper-left comer.
After a brief wait the terminal will return to SET-UP A mode.
2.1.6 Recalling SET-UP Features
Use the following procedure to recall the previously saved SET-UP
feature settings.
1. Place the terminal in SET-UP mode.
2. Press the SHIFT and R keys simultaneously. The screen will clear
and the message 'Wait'' will be displayed in the upper-left corner.
After a brief wait the terminal will return to SET-UP A mode.
NOTE
When a recall operation is performed the contents of the screen are
destroyed.
2.1.7 Resetting the Terminal
Use the following procedure to reset the terminal:
1. Place the terminal in SET-UP mode.
2. Press the 0 key on the main keyboard. The VT100 will be reset. the
power-up self test will be run. and the terminal will react according
to the. fixed SET-UP features.
2-5

3.1 INTERNAL SELF TESTS
CHAPTER 3
TESTING THE VT100
The VTlOO contains three self-test programs in the basic ROM mem-
ory:
Power-up test
Data loopback test
Video adjust pattern
Each test is designed to isolate a failure to the faulty module so that
the terminal may be repaired in a minimum amount of time.
3.1.1 Power-Up Test
3.1.1.1 Description -The power-up self test performs the following
functions:
1. Writes a 1 and a 0 in each bit location of RAM on the basic terminal
controller board to verify that the RAM can store each bit.
2. Writes a 1 and a 0 in each bit location of RAM on the Advanced
Video Option (AVO) board to verify that the optional RAM can store
each bit. If the AVO board is not installed. this part of the test is
skipped.
3. Reads the contents of the nonvolatile (NVR) RAM. calculates a
checksum. and then compares the checksum to the checksum
stored in the NVR.
4. Reads the contents of each ROM chip·; calculates a checksum. and
then compares the checksum to the checksum stored in each ROM
chip.
5. Turns on all keyboard LEDs, rings the keyboard bell for one-quarter
second •. and looks for the end of scan character from the keyboard
to determine if the keyboard is functioning properly.
3-1

3.1.1.2 Performing the Test-The power-up test may be started in
any one of the following ways:
1. Turn the terminal power on.
or
2. Type the following sequence to perform the test once. (The terminal
must be in the ANSI-compatible mode. In SET-UP Bgroup switch 3
equals a 1.)
ESC (2;1y
or
3. Type the following sequence to perform the test continuously. (The
terminal must be in ANSI-compatible mode; in SET-UP B. group 2
switch 3 equals a 1.)
ESC [2;9y
or
4. Reset the terminal.
NOTE
The continuously running test will end only if an error is found or the
power is turned off.
Any error found by the power-up ,.5eif test will b8 displayed on the
terminal screen and/or LEDs L1 through L4 on the keyboard. Tables 3-1
and 3-2 provide the meanings for the error codes.
3 .1 .2 Data Loopback Test
3:12.1 Description -In the data loopback test the VT100 tran5mit
and receive lines are connected via a special external connector. A pre-
defined set of characters are then transmitted. The terminal receives the
characters and compares them to the characters transmitted. If the
characters do not match an error is then flagged.
3.1.2.2 Performing the Test -Use the following procedure to per-
form the data loopback test.
' '
1. Install the approiJriate data l0opback connector. (Connector part
number 12-15336 is for EIA communications; ·part number 70-
15503-00 is for 20 mA current loop communications.)
2. Ensure that the transmit and recei~e speeds are the same.
3. Place the terminal in ANSI-compatible mode (in SET-UP B group 2
switch 3 equals a 1 ).
4. Place the terminal in ON-LINE mode.
3-2
•
5. Type the following sequence to perform the test once;
ESC [2;2y
type the following sequenc.e to .perform the test continuously.
ESC {2;10y
NOTE ..
The continuously running test will end only if an e~ror is found or the
power is turned off.
Any er:ror found by the da~ l~opback self. t~~t will be displayed on
the terminal screen. Table 3-2 provides the meanings of the error codes.
3.1 .3 Video Adjust Test·
3.1 .3.1 Description -The video adjust test provides a full screen .. of
"'Es'" for the display height. width. and linearity adjustments. The test
pattern is internal to the terminal and is not sent to the host computer.
3.1.3.2 Performing the Test -Use the following procedure to dis-
play the test pattern.
1. Place the terminal in ANSI-compatible mode (in SET~UP B group 2
switch 3 equals a 1 ).
2. Place the terminal in LOCAL mode.
3. Type thefollowing sequence
ESC #8
3.1.4 Error Codes
If execution of any self-test produces an error. the test stops auto-
matically. There are two broad categories of ·errors: fatal and nonfatal.
Fatal errors cause the terminal to immediately stop all operation., No
intelligible information is displayed on the scr:een; however. the screen
may not be blank, but will contain a random pattern of characters. The
only error indication (except the hung terminal) is a possible error code
displayed on the programmable keyboard LEDs (L1 through L4); how-
ever. no terminal function. including the lighting of LEDs. is guaranteed
on a fatal error. The possible fatal errors and the LEO· codes are listed in
Table 3-1.
Table 3-1 LED Error Codes
Error
L1 L2
L3
L4
ROM 1 checksum error
OFF OFF
OFF
ON
ROM 2 checksum error
OFF
OFF ON OFF
ROM 3 checksum error
OFF
OFF ON ON
ROM 4 checksum error
OFF
ON OFF
OFF
Main Data Ram error OFF
ON OFF ON
3-3

Nonfatal errors do not hait theterminal processor. Instead. the termi-
nal is forced to LOCAL mode. and an error code character is displayed in
the upper-left comer of the screen under the blinking cursor.· Addition-
ally, if one or more nonfatal errors occurred while the testwas repeating
continuously. the entire screen would flash from white to black to white
about once per second as an alarm. This would continue until the termi-
nal was reset. There are four types'of nonfatal errors:
1. Advanced Video Option data RAM (AVO)
2. Nonvolatile data RAM checksum error (NVR)
3. Keyboard missing or malfunction (KBD)
4. Data loopback error ('Data) "·
Table 3-2 shows the possible nonfatal error characters which may
appear Oh the screen and the failure Which each character represents.
Table 3-2 Displayed Error Codes
Displayed Fault
Detected
_ .• j•
Character
AVO
NVR
KBD
Data
1 x
2 x '
..
3 x x
4 x
5 x x
6 x x
7 x x x
8 x
9 x x
: x x
: x x x
< x x
= x x x
> x x x
? x x x x
Note: See Table 1-2 to determine the correct module to replace.
3.2 USE OF THE PMK04 TESTER
The PMK04 tester is compatible with the VT100. Consult the
PMK04 Operator's Manual for instructions on how to use the tester.
3-4
4:1 . ' G!~NERAL
CHAPTE'R 4
VIDEO ALIGNMENT
This chapter describes the alignment of the video monitor. All of the
individual adjustments do not have to be performed each time the mon-
itor is aligned: however .. each adjustment should always be checked
since many of the adjustments are interdependent.
Figure 4-1 shows the alignment templates used in this procedure. If
the mylar adjustment templates are not available, reproduce the tem-
plates shown in Figure 4-1 on a separate piece of paper. Cut out the
shaded area on each and use these copies to perform the adjustments
in place of the mylar templates.
4.2 MONITOR ADJUSTMENTS
The following paragraphs describe the alignment of the video mon-
itor. All adjustments must be made under the following conditions:
1. Normal video 'mode (~hite characters on. a dark background)
2. 80 characters per line mode
3. ANSI-compatible mode
4. LOCAL mode.
4.2 .1 Brightness
Use the following procedure to adjust the brightness control on the
monitor board.
1. Increase the brightness to the maximum level with the '"t" key in
SET-UP mode.
2. Remove the terminal top cover (Paragraph 5.10)..
3. Adjust R117 (Figure 4-2) until the display raster isvisible; then back
off on the adjustment until the rastM disappears.
4. Replace the terminal top cowr.
4-1

4.2.2 FOCUS
Use the following procedure to check and adjust the focus.
1. Type the following sequence.
ESC #8
2. Examine the characters at the four comers and in the center of the
screen. The individual dots in the vertical segment of the "E" should
be visible in each character.
NOTES
In some cases. the operator may want the focus mlsadjusted to suit
personal preference.
If the focus is adjusted correctly do not perform the following steps.
3. Remove the terminal top cover (Paragraph 5.10). ·:
4. Adjust R122 (Figure 4-2) forthe best overall character presentation.
5. Replace the terminal top cover if no further adjustments are re-
quired.
4.2.3 Yoke
Use the following proeedure to check'and adjust the yoke.
1. Type the following sequence.
ESC #8
2. With the top cover still on the terminal. place the VT100 alignment
template (part number 940322-3) on the screen. Ensure that the
template lies as flat as possible on the screen.
3. Verify that all four sides of the display presentation are parallel to
the red shaded area of the alignment template.
NOTE
If the yoke is adjusted correctty do not perform the following steps.
4. Remove the alignment template from the screen.
5. With the dark blue or black felt-tip pen, mark the four edges of the
screen.
6. Remove the terminal top cover (Paragraph 5.10).
7. Tape the VT100 alignment template to the screen. To orient the
template use the felt-tippen marks placed on the screen in step 5.
8. Loosen the yoke collar clamp screw (Figure 4-3) and turn the yoke
until the four sides of the display presentation are parallel to the red
shaded area of the alignment template.
4-2

MIN- ..... ...-
MAX
·~
o•
0CC
.- v
1-N
>M
0
v
0)
CHARACTER WIDTH
MA-2069
RED
SHADED
AREA
CHARACTER HEIGHT
MIN
MAX
VT100 9403246-38
--.--------.---.. _____________
--- ~-~---------------------------
RED SHADED AREA
VT100 ALIGNMENT TEMPLATE
9403220-3
Figure 4-1 Video Alignment Templates
4-3

10
J101
0 0
VERT. HOLD
BAIGlfTNES
B
~
FOCUS
~
BVIDEO
CENTERING
VERT.
LINEARITY
B
HOAZ HOAZ
LINEARITY WIDTH
Rl~
a ® ®
VERTICAL
,1
HEIGHT
J104
0 0
Figure 4-2 Video Monitor Board Adjustments
i
YOKE COLLAR
CLAMP SCREW
Figure 4-3 CRT Adjustments
9. Ensure that the yoke is pushed all the way forward toward the face
of the CRT. While holding the yoke in place. tighten the yoke collar
clamp screen.
10. Replace the terminal top cover if no further adjustments are re-
quired.
4.2.4 Vertical Height ,,
Use the following procedure to check and adjust the overall presen- ),
tation height.
1. Type the following sequence.
ESC #8
4-4
2. With the top cover still on the terminal. place the VT100 alignment
template on the screen. Ensure that the template lies as flat as
possible on the screen.
3. Verify that the top and bottom lines-ofthe. presentation are coVered
by the red shaded area of the adjustment template.
NOTE
If the vertical height is correct do not perform the following steps.
4. Remove the alignment template from the screen.
5. With the dark blu1e or black felt-tip pen. mark·the four edges of the
screen.
6. Remove the terminaf top cover (Paragraph 5. 10).
7.Tape the VT100 alignment template to the screen. To orient the
template use the felt-tip pen marks placed on the screen in step 5.
8. Adjust the vertical height using R110.
9. Check and adjust the vertfcal line·arity and vertical hold if needed.
10. Replace the terminal top cover if no further adjustments are re-
quired.
4:2.5 Horizontal Width
Use the following procedure to check and adjust the overall presen-
tation width.
1. Type the following sequence.
ESC fl.8
2. With the top cover still on the terminal. place the VT100 alignment
template on the screen. Ensure that the template lies as flat as
possible on the screen.
3. Verify that the first and last columns of the presentation are covered
by the red shaded area of the adjwstrnent template.
'NOTE··
If the horizontal width is correct do not perform the following steps.
4. Remove the alignment template from the screen.
5. With a dark blue or black felt-tip- pen. mark the four edges of the
screen.
6. Remove the terminal top cover (Paragraph 5.10).
7. Tape the VT100 alignment template to the screen. To orient the
template use the felt-tip marks placed on the screen in step 5.
4-5

8.Adjust the horizontal width usrng l103.
9. Check and adjust the horizontal linearity if needed.
10. 'Replace the terminal top·cover.
4.2.6 Centering
Use the following procedure to check and adjust the presentation
centering.
1.Type the following sequence.
ESC #8
2. With the top cover stitl on the terminal, place the VT100 alignment
template on the screen. Ensure that the template lies as flat as
possible on the screen.
3. Verify that the display presentation falls within the red shaded area
on the alignment template. If the presentation is too large or toe>
small perform the appropriate width or height adjustment.
NOTE
If the centering is correct do not perform the following steps.
4. Remove the alignment template from the screen.
5. With a dark blue or black felt-tip pen, mark the four edges of the ·
screen.
6. Remove the terminal top cover (Paragraph 5.10).
7. Tape the VT100 alignment template to the screen. To orient the
template use the felt-tip pen marks placed on the screen in step5.
8. Set A 103 fully counterclockwise.
9. Center the presentation by rotating the centering tabs on the yoke
(Figure 4-3).
NOTE
A103 may be used to move the display presentation a small dis-
tance horizontally. If A 103 is misadjusted, the left side of the screen
presentation may be distorted.
10. Replace the terminal top cover ·if no further •adjustments are· re-
quired.
4.2.7 Vertical Linearity
Use the following procedure to check and adjust for uniform charac-
ter height
1. Type the following sequence.
ESC #8
4-6
2. Using the VT100 character height template (part number 94-
03246-38) verify that the characters located near the four corners
and the center of the presentation fall between the minimum and
maximum units of the template.
NOTE
If the vertical linearity is correct do not perform the following steps.
3. Remove the terminal top cover (Paragraph 5.10).
4. Adjust the vertical linearity using A 102.
5. Check and adjust the vertical height and vertical.hold rt needed.
6. Replace the terminal top cover if no furt~r adjustments are re-
quired.
4.2.8 Horizontal Linearity
Use .the following procedure to check and adjust for uniform charac-
ter width.
1. Type the following sequence.
ESC #8
2. Using the VT100 character width template (part number 94-
03346-3A) verify that the characters located near the four corners
and the center of the presentation fall between the minimum and
maximum limits of the template.
NOTE
If the horizontal linearity is correct do not perform the following
steps.
3. Remove the terminal top cover (Paragraph 5.10).
4. Adjust the horizontal linearity using L 102.
5. Check and adjust the horizontal width if needed.
6. Replace the terminal top cover if no further adjustments are re-
quired.
4.2;9 Vertical Hold
Use the following procedure to adjust the vertical hold.
1. Remove the terminal top cover (Paragraph 5.10).
2. Set A101 fully counterclockwise.
3. Check and adjust the vertical height and vertical linearity if needed.
4. Replace the terminal top cover if no further adjustments are re-
quired.
4-7

CHAPTER 5
MODULE REMOVAL AND REPLACEMENT
6.1 GENERAL
This chapter. contains procedures for the removal and replacement of
the mechanical subassemblies of the VT100.
Figure 5-1 lists all removal procedures in this chapter and the se-
quence in which they are to be performed. As an example. Figure 5-1
illustrates that to remove the de power harness. the top cover. bottom
cover. and power supply removal proce'dures must be performed first.
6.2 ACCESS COVER
The following procedure describes the removal and installation of the
terminal access cover.
1. Remove power from the terminal by disconnecting the ac plug.
2. Unplug the keyboard.
3. Unplug the connectors from the video input/output jacks.
4. Disconnect the communications cable.
5. With a blade-type screwdriver loosen the four captive screws hold-
ing the access cover (Figure 5-2).
6. If the 20 mA Current Loop Option is installed, gentlypull the access
cover away from the terminal about two inches: then reach in and
disconnect J5 from the terminal controller board.
7. Remove the access cover.
8. To install the access cover. perform steps 1 through 7 in reverse.
6.3 TERMINAL CONTROLLER BOARD
The following procedure describes the removal and installation of the
terminal controller board.
1. Perform the terminal .access cover removal procedure (Paragraph
5.2).
5-1