HP 3562A Service Manual page 477

MOD E L 3S62A
8-61 A2, A22 SYSTEM CPU/HP'S
The i nformation in this section shou ld be used to isolate fau lty subb locks i n the A2 and
A22 System C PU/H P I B assem b l ies. A l l proced u res assu m e the Fau lt I so l ation proced u res
of Section V I I have been used to determ ine which board has fai led, and the C i rc u it Descrip­
tions of Section V I are u nderstood.
Service procedures described in this section are performed with
the protective co vers remo ved and power applied. Hazardous
voltage and energy available at many points can, if contacted, result
in personal injury.
Do not insert or remove a n y circuit board in the HP 3562A with
the line power turned on. Power transients caused by insertion or
removal m a y damage the circuit boards.
How to Use This Section
Verify
Afh�r-Repair
Troubleshooting Hints
1 . Only + 5 Vdc and ground are req u i red to trou bleshoot the A2 C P U/ H P I B assemb ly.
To run the A2 C P U/H P I B assem bly without the rest of the i nstrum ent, put j u m pers
A2 J 1 5 and A2 J 1 6 in test (T) position.
2. The A2 CPU/H P I B can be ru n on an external c l ock by grou n d i ng A2 TP3 and connecting
a TTL l eve l , 8 MHz c lock to A2 T P4.
3. U ndefi ned fai l u res are most l i kely caused by stu ck b its. This is occurring if the status
L E Ds (A2 DS2) are a steady state value i nstead of changing rap id ly. Go to the i n itial
cond itions test (A).
WARNING
CA UTION
Start troubleshooting by using figu re A2-1 . This proced u re d i agram
descri bes the best order to perform the tro u b l es hooting tests based
on the sym ptoms observed .
For the component l ocato r and schematic refer to Section IX. For the
location of cables and boards refer to f i g u re 4-1 in Section IV.
Use the osc i l l oscope waveforms in tab le A2-5 to see co rrect operation
at various test poi nts in the assembly.
Use tabl e A2-6 to determine which adj u stments and tests need to be
done to com plete i n strument servi ce.
S E RV I C E
8-27