Troubleshooting
Note
•
If an error code is being displayed by the HP 8 1 12A you must press
a key,
for example, to return the microprocessor to normal
operation before troubleshooting.
•
The component layout and locator for the main board Al is at the
end of this chapter.
Address Decoder
The address decoder UlOO can be checked with signature analysis.
Set the microprocessor to free run mode as follows:
1. Set the Pl wire on board A3
(
See Chapter 10.7) to position
P l .
2. Disconnect Jumper A2W l .
3. Connect RES on A 3 t o ground for a short time t o ensure the
microprocessor is reset.
4: Connect the signature analyser ground to the microprocessor
board ground, then set the signal analyser as follows:
Signal
Analyzer
Start
.r
Stop
.r
Clock
\
Ground
A3 µP Board
Connections
TP "SA"
TP "SP"
TP "E"
Ground
5. Verify that the reading at the microprocessor board +5 V is 0003.
6. Check the signature of board inputs against those given in
Table 1 0.3-6
10.3-14 Servicing the Timing and
Slope Generators
LA3
SRC
LA4
P I C
LA5
CLR
U100
MAMO
r- WS1
W I C
DIC
r- WS2
LRC
RSA
A3W4
Figure 1 0.3-7. Address decoder - Simplified block diagram
Summary of Contents for 8112A
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Page 294: ... 8 X2l 2 X2 Figure A 1 Mechanical Parts 1 A 2 Replaceable Parts ...
Page 295: ...MP MP3 MP MP2 MP4 MPS MP 1 2 MPS MP MP I B ElElElEl Replaceable Parts A 3 ...
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Page 378: ...Figure B 14 Mechanical Parts 1 B 44 Backdating ...
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