TroubleshootingProcedures
WFM90D and WFM91D ServiceManual 6-49
Usethis proc edure when
thegraticule is ok, but the
Audiodisplay is distorted
ornot visible.
Removethe D isplay module. (For instruments with
serialnumbers below BO20100, removethe Dis play
moduleand Backlight board. ) Power up the
instrumentand selec t DEFAULTPRESETs from the
CONFIGURE menu. Select the Audio display mode.
Attachan audio input s ignal from 0 to +8 dbu.
No
Yes
No
Yes
Replacethe
Topboard.
Checkthe AUDIO IN signal:
(J15is on the Bott om board.)
J15-4= Check f ora gain of X1above
inputsignal level. T he Audio Amplifier
gainis always X1 in +8 dbu. Thesignal
levelshould change as diff erent
referencedbu levels are s elected from
themenu.
Isthe
AUDIOIN
signal
OK?
Checkthe audio def lection signals:
(J9is on the back ofTop board.)
J9-1= 1 Vpp, 2 VDC
J9-3=+1Vto+3.8Vrampwitha
35ms period
Arethe audio
deflectionsignals
OK?
Replacethe Input board.
Replacethe Bott om board.
Figure6 -24: Flowchart for bad audio display