HP 3562A, Service Manual

Page: 537 / 570

MOD E L 3S62A S E RVICE
8-1 1 AS, GLOBAL RAM/DISPLAY CONTROLLER
A 1 7, DISPLAY INTERfACE
The information in this section shou ld be used to isolate fau lty subblocks on the global
RAM and display interface boards. All procedu res assume that the fau lt iso lation procedures
in section VI I have been used to determ ine that one of these boards has failed and that
the circ u it descriptions in Section V I are understood .
WARNING
Service procedures described in this section are performed with
protective co vers remo ved and power applied. Hazardous voltages
in these circu its can cause personal injury if contacted.
CAUTION
Do not insert or remove an y circu it board in the HP 3562A while
power is on. Power transients caused by insertion or removal may
cause damage to circu its on the board being changed or on other
boards.
How to use this section
Start
Relerence
After-Repair
Start troubleshooting with part A, G l obal RAM Diagnostics. Use of
this section w i l l isolate the problem to a subblock of A8 or A1 7.
Refer to Section IX for the com ponent locators and schematics. Refer
to figure 4-1 in Section IV for location of cables and boards. Refer
to figure 7-4 in Section VI I for power-up test codes.
Use table A8-1 0 to determine which adj ustments and tests need to be
performed to complete instrument service.
Trclubleshooting Hints
1 . G lobal RAM or Display I nterface problems can blank or garble the display. The fol low­
ing featu res simpl ify fau lt isolation when the display is not functio n i ng properly:
a. Some diagnostic resu lts are annunciated on the A2 L E Ds as wel l as on the 1 345A
d isplay. Table A8-1 exp lains the A2 L E D fau lt codes.
b. The A2 LEDs will display 87 when the power-up tests and cal ibration are fin ished.
If this does not occur, refer to section V I I , Fault I solation.
2. The LED at the top of the A8 board (C R1 ) indicates RFD on the system bus. It is not
used to service the A8 board.
8-87