HP 8112A, Operating, Programming And Servicing Manual

Page: 183 / 406

Trouble shooting
Preparing the HP 81 12A
for servicing
Every time the instrument is switched on, or when an EST command
is received on the HP-IB, the HP 8 112A executes a self-test. If a
fault is detected an error code is displayed, otherwise the instrument
is ready for operation. The error code can be used to locate the fault
by referring to the following flowchart.
If more than one fault exists,
only the first one is detected and displayed. After this is successfully
repaired, the self-test will be able to proceed further and detect other
remaining faults .
•
ATTENTION
Static Sensitive
The HP 8112A contains static-sensitive devices.
Ensure that "static-safe " precautions are taken to
prevent electro-static discharge when the instrument
covers are removed.
1 . Remove the rear of the instrument by unscrewing the two TORX
fastening screws.
2. Remove the single screw securing the instrument's case
underneath the instrument.
3. Remove the case by sliding it backwards. You may need to use a
screwdriver in one of the case ventilation holes to gently lever the
case back. It is held tightly by the RFI seals at the front of the
frame.
4. Remove the four screws securing the microprocessor board.
5. Lift the microprocessor board and stand it vertically by placing
the cut-outs on the edge of the board over the locating lugs on the
inside of the right-hand side-panel (as seen from the front of the
instrument).
6. Remove the screen covering the control board.
7. Lift the control board and stand it vertically on the inside of the
left-hand side-panel.
Control Board
Microprocessor Board
0
0
0 0
Figure 1O.1-3. HP 8 1 1 2A in its servicing position
Instrument Overview and Troubleshooting Guide 10.1-3