HP 3562A Service Manual page 507

MOD E L 3S62A
The D FA f u n ctional test performs a zoom meas u rement o n data created by the system
CPU and stored in gl obal RAM. The test s i m u l ates meas u r i n g a 1 6 k H z squ are wave with
a zoom window 1 0 k H z wide, centered at 1 6.5 k H z . The resu lts are processed by the FFT
and FPP boards to create a power spectru m . The power spectrum is checked for proper
a m p l itu de of the fun damental and noise floor.
T h i s test exerc ises a l l c i rcu itry in the D FA except the trigger c i rcu itry in the measurement
state m ac h i ne block and the trigger LED control b lock on the A6 board . Prior to erform ing
this measu rement, the inte rru pts used to i n d icate the end of measurement are tested . If
e ither of the two i nterrupt tests fail, the zoom meas u rement is not performed. This rotects
agai n st fai l u re of the program to ru n to com pletion. When the i nte rrupts are i noperab le,
the D FA can not signal the CPU that the meas u rement is com plete and the program wa its
i ndefinately.
If the D FA fu nction passes, the fol l owing messages are d isplayed :
D FA Fi ltered Chan I nterrupt
D FA U nfi ltered Chan I nterru pt
DFA Fu nctional Test
The fi ltered and unfi ltered i nterrupt tests refer to the types of i nterru pts used to perform
the meas u rem ent. Data is transferred from global RAM i nto the d igital f i lter control ler,
where it may or may not be fi ltered, depen d i ng on the type of measu rement req u i red.
There is an i nterrupt i n d i cati ng end of meas u rem ent for each of the the two cases.
If either of the i nte rrupt tests fai l , test the local bus (fi rst) and then the DMA bus with
the d i agnostic tests of the same name. The descri ptions of these tests appear late r i n this
section.
I f the DFA functional test fai l s, beg i n troubleshooting by r u n n i n g the local bus test; it
has to fu nction correctly before anyth i n g else can be tested.
I f tile D FA fu nction test passes, the AS, A6 assem bl ies are probably f u n cti o n i ng correctly
with two exceptions: neither the trigger c i rcu itry in the measu rement state machine block
nor the c i rcu itry in the trigger L E D control block on the A6 board are exercised by this test.
If the trigger is fai l i ng and the prob lem has been isolated to the AS, A6 asse m b l ies, start
trou bleshooting the Trigger Co ntro l PAL (A6 U409) and the Start/Stop Contro l PAL
(A6 U309). Other possible problem areas i n c l ude the AM9S1 3 cou nter (A6 U1 09) and the
trigger i nterrupt f l ag (A6 U303).
If the 'TR I G G E R I N G' or 'MEAS U R I N G ' L E Ds are not fu ncti o n i n g co rrectly, start
tro u b l eshooting the Trigger L E D Control S u b b l oc k .
Passes
Passes
Passes
S E RV I C E
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