Insignia NS-50P650A11 Sparkles VA won't adjust

[SHADOW3277]

Hello. Have another TV that was saved from my local recycling center. When turned on, it has sparkles on the entire screen over the picture. The VS panel voltage is 206 and that is what I get at the TP. The VA voltage is supposed to be 55 but it will only go between 33-37. I jumped the control board after unhooking the LVDS and I get the test patterns and the sparkles remain. I'm guessing the Y-Main is bad? The TV uses Samsung parts. Thanks for your help.

[Alastair E]

Re: Insignia NS-50P650A11 Sparkles VA won't adjust

How is VSC and -Vy...?

[SHADOW3277]

Re: Insignia NS-50P650A11 Sparkles VA won't adjust

How is VSC and -Vy...?

VSC jumps anywhere between 218 and 232 (supposed to be 180)
For the life of me can't find a TP for VY.

[Alastair E]

Re: Insignia NS-50P650A11 Sparkles VA won't adjust

VSC should be as written on sticker--and defo shouldn't jump around...

-Vy test-point is often across resistor near the buffer-board connectors.

[Alastair E]

Re: Insignia NS-50P650A11 Sparkles VA won't adjust

Cant see it either in yer pic--Maybe they are just using VSC as a measurement ref, then -Vy will be right too--seeing they both come from same DC-DC converter.

Clean and re-set that Set-VSC pot to the correct voltage.--See what happens...

[SHADOW3277]

Re: Insignia NS-50P650A11 Sparkles VA won't adjust

VSC should be as written on sticker--and defo shouldn't jump around...

-Vy test-point is often across resistor near the buffer-board connectors.

Yeah, VSC shows 180 on the sticker but it won't stay steady.

I still can't find VY. I went over the service manual and it lists VS, VA, VCC, VDD, and VE but no VY test point.

[SHADOW3277]

Re: Insignia NS-50P650A11 Sparkles VA won't adjust

Cant see it either in yer pic--Maybe they are just using VSC as a measurement ref, then -Vy will be right too--seeing they both come from same DC-DC converter.

Clean and re-set that Set-VSC pot to the correct voltage.--See what happens...

Tried adjusting VSC and it still just randomly jumps around. Cant get it at 180.

[Alastair E]

Re: Insignia NS-50P650A11 Sparkles VA won't adjust

Hmm--Try a new pot...?

--Check the diodes and caps on that DC/DC converter? Summit odd going on round there. Should set up nice and smooth/easy, with pot around its centre position, with correct VSC.

There's a Opto-coupler feedback loop to the controller IC that runs that DC/DC converter, try checking the voltages on/around there--poss the opto is stuffed or the controller chip Caps and diodes first I would check...

On one Samsung--cant remember which, There's a diode rec 1N4007 off that DC/DC converter that goes short--but that usually results in nothing at all on the screen....

Wrong VSC would definitely affect the operation of the panel--prob give the Mal-Discharge you have, and doesn't need to be a wildly out voltage either....

[SHADOW3277]

Re: Insignia NS-50P650A11 Sparkles VA won't adjust

Hmm--Try a new pot...?

--Check the diodes and caps on that DC/DC converter? Summit odd going on round there. Should set up nice and smooth/easy, with pot around its centre position, with correct VSC.

There's a Opto-coupler feedback loop to the controller IC that runs that DC/DC converter, try checking the voltages on/around there--poss the opto is stuffed or the controller chip Caps and diodes first I would check...

On one Samsung--cant remember which, There's a diode rec 1N4007 off that DC/DC converter that goes short--but that usually results in nothing at all on the screen....

Wrong VSC would definitely affect the operation of the panel--prob give the Mal-Discharge you have, and doesn't need to be a wildly out voltage either....

Ok, I tested with my meter and could not find any shorts. I unhooked the YSUS and checked VA several times and it still won't go above 37 even with the Y main unhooked. I went ahead and took out the Y, X and buffer and found no shorts on those.

[SHADOW3277]

Re: Insignia NS-50P650A11 Sparkles VA won't adjust

Popped in a new power supply. All good now. Thanks for the help!

[tom66]

Re: Insignia NS-50P650A11 Sparkles VA won't adjust

Interesting - first time I've seen a plasma with low Va. Similar maldischarge effects to Vs.
BTW since this is a Samsung panel it does not have -Vy only Vsc and Vsch (which is confusingly Vsc on LG panels.)