Troubleshooting; Address Decoder - HP 8112A Operating, Programming And Servicing Manual

Troubleshooting

Note

Address Decoder

10.3-14 Servicing the Timing and
Slope Generators
If an error code is being displayed by the HP 8112A you must press
n
a key, (LCL) for example, to return the microprocessor to normal
3
operation before
The component layout and locator for the main board Al is at the
n
end of this chapter.
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 Pl.
2. Disconnect Jumper A2Wl.
3. Connect RES on A3 to ground for a short time to 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 f
s t o p
f
Clock t
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 10.3-6
Figure 10.3-7. Address decoder - Simplified block diagram
troubleshooting.
A3 pP Board
Connections
TP "SA"
TP "SP"
T P "E"
Ground
/ - w s 2 LRC