HP 3562A Service Manual page 555

MOD E L 3562A
8-11 3 A9, FAST FOURIER TRANSFORM (FFTJ PROCESSOR
The information in this section should be used to isolate fau lty subb locks on the FFT board.
A l l proced u res ass u me that you have used the fau lt isolation proced u res i n Section V I I
to determ ine that this board has fai l ed and that you have read and u nderstand the c i rc u it
descri ptions i n Section V I .
Service procedures described in this section are performed with
protective covers removed and power applied. Hazardous voltages
in these circuits can ca use personal injury if contacted.
Do not insert or remo ve any circuit board in the HP 3562A while
power is on. Power transients caused by insertion or removal m a y
cause damage to circu its o n the board being cha nged o r o n other
boards.
How to use this section
Start
Procedure
Reference
Aft. e r-Repai r
TfClubleshooting Hints
1 . The FFT status L E Ds shou ld be O FF d u ring normal operation. They are not used to
service the board .
2 . A major portion of the FFT process is add res s i ng. B e s u re you u nderstand w h i c h parts
of the c i rc u it are part of the add ress ing block. Refer to the b lock d iagrams in the c ircu it
descriptions in Section V I .
WARNING
CA UTION
To tro u b l eshoot the FFT board, use the FFT d i agnostic tests to f u rther
isolate the prob lem. C i rc u it descriptions i n Section V I p rovide the
backgrou n d for u nderstand ing how the FFT board c i rcu its work.
On ce the problem has been local ized to a bl ock of c i rcu its, one of
the th ree d igital sig natu re an alysis (DSA) tests s hou ld be used to
trou bleshoot i n d ividual c i rcu its. Waveforms are provided in table A9-7
to demonstrate the correct appearance of the DSA clock and start/stop
signals.
Refer to Section IX for the component locato r and sc hematic. Refer
to figure 4-1 in Section IV for the location of cables and boards.
Use tab l e A9-8 to determ ine which adjustments and tests need to be
done to com plete i n stru ment service.
S E RV I C E
8-1 05