HP 3562A Service Manual page 493

MOD E L 3562A
8-8 A4 LOCAL OSCILLATOR
The i nformation in this section s h o u l d be used to isolate fau lty s u b b l ocks i n the A4 Local
Osc i l l ator (LO). All proced u res ass u m e the Fau lt I solation p roced u res of Section V I I have
been used to determ i n e w h i c h board has fai led, and the c i rc u it descriptions of Section
V I are u nderstood .
Service procedures described in th is section are performed with
the protective co vers removed and power applied. Hazardous
voltage and energy a vailable at many points can, if contacted, result
in personal injury.
Do not insert or remo ve an y c ircuit board in the H P 3562A with
the line power turned on. Power tra nsients caused by insertion or
remo val may damage the circuit boards.
How to Use This Section
Star't
Reh�rence
Verify
Aft��r-Repair
Troubleshooting Hints
1 . I f the LO fu nctional tests pass, but the 'Output S i ne Check' (7-8, part E ) fa i l s, start
troub leshooting with the LO Output Buffer (U54). T h i s output buffer is not tested by
the self-tests.
WA RNING
CA UTION
The pri mary trou b l eshooting method for the LO assem bly is to use
the self-tests to deter m i ne which s u bblocks and poss i b l e com ponents
are fail ing. Signature analysis is then used to troubleshoot the individual
sub blocks suspected of fa i l i n g . Start tro u b l eshooting by u s i n g part A,
" Local Osc i l l ator D i agnostics".
For the component locator and schematic refer to Section IX. For the
location of cables and boards refer to f ig u re 4-1 in Section IV.
Use the osci l loscope waveforms i n tab le A4-5 to see correct operation
at various test poi nts in the asse m b ly.
Use table A4-6 to determ ine which adj u stments and tests need to be
done to com plete i n stru ment service.
S E RV I C E
8-43