VIZIO VP423 no display

[ajshoe]

Have a VIZIO VP423 that turns on (front name plate goes from orange to white) - power clicks on, all voltages are present on PWB. on Y_SUS Vsch = 55-77 Volts, Vscan = 185-192 Volts. On X_SUS Ve = 1.9V.

Is this a PWB problem ?

[freakaftr8]

Re: VIZIO VP423 no display

I would try disconnecting the power connector to the X sustain. (Far right board) Your VE is way too low I'm suspecting an x sustain short on that board. Can you post a picture of the X sustain board

[ajshoe]

Re: VIZIO VP423 no display

X_sus board is posted above - I'll check for shorts and post some closeup pics of board.

[freakaftr8]

Re: VIZIO VP423 no display

My apologies. Didn't see the pics before. How does f4001 test on xsus?

[ajshoe]

Re: VIZIO VP423 no display

nothing shorted. fuses F001 and F003 are good

[ajshoe]

Re: VIZIO VP423 no display

[ajshoe]

Re: VIZIO VP423 no display

also Vsch and Vscan are fluctuating

[freakaftr8]

Re: VIZIO VP423 no display

Then in that case why don't you try removing the buffer board connections from the ysus. Possibly a shorted buffer board loading the system down

[ajshoe]

Re: VIZIO VP423 no display

probably worth giving a little history of set. was working and would shut off. only way to get it to turn on with display was to wait overnite. I got the set and plugged it in - it worked. left it on overnite and next morning sound on but black display. after a week - I can't repeat this symptom. just black display but it seems to turn on (and stays on) - voltages are good and front vizio nameplate turns white from orange. changed main board with NEW one - same symptoms. don't think bad buffers would cause this scenario.

[ajshoe]

Re: VIZIO VP423 no display

disconnected sustain boards & hooked up 2 100 watt light bulbs across Vs and ground. power supply comes on, bulbs come on and stay on. repeat test with X sustain plugged in - same result. All voltages are good. any ideas ???

[freakaftr8]

Re: VIZIO VP423 no display

What is your reading for VA?

[ajshoe]

Re: VIZIO VP423 no display

Va is 54 V. measured it with 2 100 watt bulbs on Vs and with y & x sustain boards plugged in

[ajshoe]

Re: VIZIO VP423 no display

what I meant by earlier post - Va was 54v with 2 100 watt bulbs on Vs to grd with x y sustains disconnected. ran test again with sustains connected and Vs was 54v also.