HP 3562A Service Manual page 506

S E RV I C E
3 . I f fu l l-span functions correctly but zoom mode fai l s o n both chan nels, start trou b l e­
shooting the LO Signal/Constant Select su bblock.
4.
If freerun meas u rements operate correctly, but triggered meas u rements do not, start
tro u b l eshooti ng the Trigger Contro l PAL (A6 U409) and the Start/Stop Control PLA
(A6 U309).
5. If a l l the D FA diagnostic tests ind icate no fai l u re, yet the i nstrument sti l l has a prob lem
making a measu rement, run the ADC diagnostic called D I G T AL T E ST. This test provides
data to the DFA from the instrument front end, performs a measurement, and analvzes
the resu lts. T h i s a l l ows you to test the i n p ut data b it stream from the ADC boards.
The key strokes used to access this d i agnostic are:
PRESET
SPCl FCTN
. . . . . . S E RV I C
A. DFA Diagnostics
The d i agnostic tests for the D igital Fi lter Assem b l y al l ow you to test groups of c i rcu its
to f u rther isolate a prob l e m . A su bset of the D FA d i agnostic tests run when the nstru ment
power is tu rned ON, d u ring S E L F T E ST, and d u ring T E ST ALL. Display the D FA d i agnostic
test menu u s i ng the fol lowi ng sequence of keystrokes:
. . .
PRESET
SPCl FCTN
. . . . . . S E RV I C
The menu now contains the fol lowing entries of DFA d i agnostics:
D FA FU N C T N
F I LT E R T E ST
LOCAL B U S
DMA B U S
F I LT E R B U S
D FA PATT 1
D FA PATT 2
Deta i l s of each test fo l l ow :
D FA F U N CTN
The DFA function test shou ld be u sed to test the overal l health of the d i g ital fi lter assem bly
&
(AS A6). Other d i ag nosti c tests s h o u l d be used to f u rther isolate pro b l e m s as descri bed
in the fol l owi ng paragraphs.
8-56
R E S E T
T E ST . . . . . . T E ST
I N PUT
. . R E S E T
.
T E ST . . . . . . T E ST PROC
. . . . . . ADC
. . . . . . T E ST DFA
MO D E L 3562A
. . D I GTAL
T E ST