HP 3562A Service Manual page 511

MO D E L 3S62A
3 . I f Transient Test #1 passes and other transient tests f a i l , the problem is probably one
of the fi lter !Cs. The s ignatu re tests cannot be used to verify this, as is exp l a i ned l ater
in this d iscussion.
4. Perform the F ilter Bus test. I f it passes, the p rob lem is probably in a f i lter IC; switch
fi lter I C s between channels to see if the p rob lem changes chan n e l s .
When the test is run with loop mode off, the fi lter ICs execute a test routine that generates
five d ifferent signals (cal led transients) with in the IC on which measurements are performed.
Measu rement data is transferred to global RAM through the di gital fi l te r bu sses and the
gl obal data bus interface block. The system C P U performs a s ignatu re analysis on the
d ata and reports any l i ne with an i n correct s ignature.
This test a l l ows you to isolate the meas u rement and data storage processes from the in put
p rocess. The fi rst fou r measu rements are zoomed (real and i magi nary data) and the fifth
is baseband (real data, only). Fa i l u re messages tel l you th ree thi ngs: w h i c h of the five tests
fail ! (these are cal led D FA Trans ient Tests), which channel and fi lter IC fai l (e.g., CH1 Real
Fi lt), and which bits fai l . The fi lter I Cs are d u p l i c ate parts mou nted in sockets al lowing
you to switch parts between channels to verify fai l u res.
When the test is run with loop mode on, the f i rst trans ient test (on ly) is performed, repeti­
tively, so that d i gital s ignature analysis m ay be used to iso l ate pro b l e m s in the output
path from the fi lter I Cs through the gl obal bus i nterface to the global bus.
To activate the DFA PATT 1 d i agnostic test, move j u mper AS J 7 to its test position and
press the softkey titled D FA PATT 1 .
I f this test passes, the fol lowing su bblocks are probably fu nctio n i ng correctly:
G l obal Bus DMA Control
Address Output Registers
G l obal Data Bus I nterface
CHAN 1 Digita l Fi lter Data Bus
CHAN 2 Di gital Fi lter Data Bus
C H A N 1 Di gital Fi lter
C H A N 2 Di gital Fi lter
D FA PATT 2
The d igital fi lter pattern #2 d i agnostic is a d igital s ignature analys i s test. I t is u sed to test
the measurement and control c i rcu its on the A6 board. I ts use is exp lai ned in the s ignatu re
tabl es.
S E RV I C E
8-61