HP 3562A Service Manual page 510

S E RV I C E
I f this test fa i l s and the local bus test passes, the fa i l u re is probab ly in the G l obal Bus
DMA Control or Local Data/DMA Bus I nterface. The test message d i s p l ayed on the screen
identifies which of the two should be i nvestigated along with i nformation descri bing wlhich
b it has fai led.
F I LT E R B U S
T h e fi lter bus test s h o u l d b e u sed, after the operati on of the local data bus is verified,
to test the transfer of data between the d igital fi lter b l ocks and global RAM .
The fi lter bus test transfers one word from global RAM, through the d ig ital fi lter bus, i nto
the d igital fi lter contro l ler I C, and then transfers it back to global RAM. Refer to the bl ock
d i agrams in Section VI to visu a l i ze the data path. T h i s seq uence is performed once for
each of the two channels. The test checks for either incorrect words or fai l u re to write
anyth i n g at a l l .
Fai l u re to write anyth ing, denoted by the message "DFA Chan
with measu rement control c i rcu its on A6 or the d igital f i l ter co ntro l IC correspond ing to
the channel that fai led (the meas u rement fai led to set up). Writing wrong data causes
the message "DFA Fi lter Bus
IC assoc iated with the fai l i ng c h a n n e l .
I f the fi lter bus test passes, the fol lowi n g c i rcu its a n d processes are probably fu nction ing
correctly:
Paral l e l I n put Control
G lobal Bus DMA Control
G l obal Data Bus I nte rface
Address Output Reg isters
Unfi ltered channel output of the C H A N 1 and C H A N 2 Fi lter Contro ls
The message "DFA Filter Bus
Filter Data Bus and "DFA Filter Bus 2" corresponds to the Chan 2
D igital Filter Data B us.
D FA PATT 1
The d igital fi lter pattern test #1 is used for two pu rposes: with the loop mode off, it is
a d iagnostic self-test of the d i gital fi lter b l ocks with no i n puts; with the loop mode on,
it is a signatu re test for the d igital fi lter data busses and the global data bus i nterface
b lock. It is i ntended to be u sed as fol lows:
1 . R u n the d i agnostic (loop mode off).
2 .
If Transient Test #1 fails, perform the test with loop mode on and use the signatu res
to isolate prob lems in the output path (from the fi lter contro l ler IC through the gl obal
data bus i nterface).
8-60
x "
to be d i s p l ayed and ind icates a problem with the i nterface
NOTf
1"
corresponds to the Chan 1 Digital
MOD E L 3562A
x Write," i ndicates a problem