TroubleshootingProcedures
WFM90D and WFM91D ServiceManual 6-45
Isthe
Backlightbroken?
(TheDisplay m odule
willhave a rattle
inside.)
Pressthe front
panelON button
andthen the PIX
modebutton.
Isthe
Backlighton?
(Lookin the end of
theDisplay m odule
wherethe high
voltageis
attached.)
Replacethe Top board.
Replacethe Dis play module. (For
instruments with serial numbers below
BO20100,replace the Back light board.)
Testthe Backlight power supply:
Disconnect the AC Adapter. Remove the Display
module.Attac h a 10 kΩ≥2 W resistor between
thehigh voltage connec tors using a pair of
jumperwires. At tach an oscilloscope probe to the
endof the resist orat tached to the orange
connector.Connect t he oscilloscope ground lead
tothe GND t est point on the Bottom board. Set
theoscillosc ope to 50 V/div.R econnect the AC
adapterand power up the inst rument.
CheckBacklight pow ers upply inputs:
J20-1= Ground
J20-2= 12 VDC Vin (1 Vpp ripple)
J20-3= 5 VDC (Backlight Enable)
J20-4= 1.25 VDC (1. 25-1.75 VDC as the
Backlightbrightnes s is changed using the
CONFIGURE menu)
Replacethe Bott om
board.
Usethis proc edure if
thereis no display af ter
pressingthe front panel
ONbutton.
Yes
No
No
Yes
Isthe
VIDEOOUT
signalgood?
Isthere
400VAC as
measuredon
the
oscilloscope?
Yes
No Areall of the
Backlightpower
supplyinputs
good?
Replacethe Dis play
module.(For
instruments with
serialnumbers below
BO20100,replace
theBacklight board.)
Checkthe D isplay drive signals:
(ProbeJ16 from the bac k of the Bottom
board.)
J16-9=1VDCto3VDCasVIEWis
adjustedin the CON FIGURE menu.
J16-10= (DSYNC) 0 t o +600 mV
compsync
J16-14= (SEL_EXVID) +5 VDC inPIX
modeand 0 VDC in Waveform mode
SelectPIX Mode, No Menu,
(Use100% flat f ield test signal.)
J16-6= (B) 2 VDC blanking level/ 2.5 V
peakvideo
J16-7= (G) 2 VDC blanking level/ 2.5 V
peakvideo
J16-8= (R) 2 VDC blank ing level/2.5 V
peakvideo
SelectWFM Mode+ MENU
(Use75% color bar signal. )
J16-2= (B) 0 to +1.3 V
J16-3=(G)0to+1.3V
J16-4= (R) 0 to +1.3 V
Removethe AC adapter
andthen remove the
Displaymodule and t he
Backlightboard. Reat tach
theAC adapter and leave
theVIDEO IN and VIDEO
OUTcables att ached.
Powerup the instrum ent.
Checkfor bad or
misalignedDisplay
moduleinterface c able.
Ifcable is ok, replace
theDisplay m odule.
Ifthe DI SP BRT signal is bad, replace the
Bottomboard.
Ifthe DSYN C signal is bad, replace the Top
board.
Ifthe SEL_EXVID signalis bad, replace the
Topboard.
Ifthe RGB v ideo is bad, replace the Bottom
board.
Ifthe Ras ter Drive signals are bad, replace
theTop board.
Areall of these
signalscorrect ?
Yes
No
Yes
No
No
Yes
Replacethe Dis play module.
(Forinstrument s with serial
numbersbelow BO20100,
replacethe Backlight inthe
Displaymodule. )
Figure6 -20: Flowchart for no display