Samsung QN55Q80R Bad Panel Help

[Davi.p]

Re: Samsung QN55Q80R Bad Panel Help

the test points are probably on the panel's boards, search them with mgnifier or post sectional photos

[Storyteller12]

Re: Samsung QN55Q80R Bad Panel Help

have you tested vcom on the panel boards? It must be around 7,5v. Or maybe is something about bad vgh/vgl, low value.. test those plus avdd

Sorry, I'm not a tech so you have to point me in the right direction where vcom, vgh,vhl are to measure them. I don't see anything labeled with them, but my eyes are the greatest either and the print is small.

Thanks

[Davi.p]

Re: Samsung QN55Q80R Bad Panel Help

have you tested vcom on the panel boards? It must be around 7,5v. Or maybe is something about bad vgh/vgl, low value.. test those plus avdd

[lotas]

Re: Samsung QN55Q80R Bad Panel Help

Also check the TVS Diodes on the strips with a multimeter for low resistance or short circuit.

[Storyteller12]

Re: Samsung QN55Q80R Bad Panel Help

Ok, replaced the eeprom and removed the spi on buffer board and tv reboots like it originally did. I tape off pins again with spi removed and same washed out image.

[Storyteller12]

Re: Samsung QN55Q80R Bad Panel Help

Lol. My bad, I didn’t know.

Thanks for pointing out the obvious.

[lotas]

Re: Samsung QN55Q80R Bad Panel Help

It was rather about this SPI 25Q32.

[Storyteller12]

Re: Samsung QN55Q80R Bad Panel Help

I tried doing the other winbond chip (25q40) as suggested by diah but the standby light didn’t come on and couldn’t power the tv on.

I just figured I would try this chip and see what happens.

Not really sure what to try honestly. I think this one is headed for the dump.

Any other suggestions?

[lotas]

Re: Samsung QN55Q80R Bad Panel Help

Why remove 25q80dvsig, it belongs to T-CON and it contains all your panel settings! Without it, T-CON will not work.

[Storyteller12]

Re: Samsung QN55Q80R Bad Panel Help

Sorry was sick for a few days and didn’t have a chance to troubleshoot.

So, I removed SPI (25q80dvsig) chip and removed all the tape masking pins On lvds cable. Tv turn on and stays on but no image. Its not rebooting like it was. But if i unplug the side with the bad lvds cable i no longer get an image on half the screen like I did before. So I’m assuming in need the spi chip for it to produce an image.

Would a new spi chip fix the issue?

[howardc64]

Re: Samsung QN55Q80R Bad Panel Help

Lots of transposed pictures and easily confusing. Judging from the pics in post #9 and #13, OP masked

CN1301 (I'm assuming pic is CN1301 since thats the half thats not working) pin 74-82 (can't tell from pic if mask was continuous across this range). Service manual ( closely related, likely correct CN1301 pin out. link p112 for main board pic, p129 for CN_1301 )



This is LC_VGP1_GOA, STVP1_GOA, CKVB1-4_GOA, CKV2-4_GOA

Maybe should just try to mask out the 8 gate driver pins on the bad side (CKVB1-4 and CKV1-4) per post #14 (but I think post had wrong pinout diagram : CN1300 rather than CN1301) Probably can skip CKV1_GOA for total of 7 pins since short isn't there from current test. If that works, then gradually tried fewer CKVB1-4 CKV2-4..

BTW, for precise experimental masking. I do it this way. Mark off 12 pin steps (service manual pin listing is in rows of 4) on the connector. Cut thin white paper precisely. Paper don't move when inserting the flex into the connector.

[Diah]

Re: Samsung QN55Q80R Bad Panel Help

Pins 19 or 20-26. It's hard to count those tiny pins.

if this count correct and the pin chart of lotas correct then you have just masked half of the SPI... in this case i will remove the mask and just remove the spi carefully

[Davi.p]

Re: Samsung QN55Q80R Bad Panel Help

havdd is there? try to change tape type with the thinner thing you have, usually kapton is quite thin

[Storyteller12]

Re: Samsung QN55Q80R Bad Panel Help

That whiteish picture sounds to me as you have bad vcom signal, maybe you covered that pin but it is mandatory to have it on to the panel, check vcom test point on the panel

Vcom is pins 6,7,8 and those are not covered.

[Storyteller12]

Re: Samsung QN55Q80R Bad Panel Help

how many pins you masked now LOL.. could you count on which pin masked right now.. seem you have one of gamma under mask.

Pins 19 or 20-26. It's hard to count those tiny pins.

[Davi.p]

Re: Samsung QN55Q80R Bad Panel Help

That whiteish picture sounds to me as you have bad vcom signal, maybe you covered that pin but it is mandatory to have it on to the panel, check vcom test point on the panel

[Diah]

Re: Samsung QN55Q80R Bad Panel Help

how many pins you masked now LOL.. could you count on which pin masked right now.. seem you have one of gamma under mask.

[lotas]

Re: Samsung QN55Q80R Bad Panel Help

Sometimes it helps to reduce the VGH voltage on the non-working side.
The TVS diodes on the bar were measured with a multimeter for low or short resistance.

[Storyteller12]

Re: Samsung QN55Q80R Bad Panel Help

Update, I tried covering those 2 pins as well but no luck. Same washed out image.
Also checked both winbond chips and neither are shorted and I measured 3.3v on vcc.

[Storyteller12]

Re: Samsung QN55Q80R Bad Panel Help

rubbish Samsung... why people buy this trash

You make me laugh. So true, but unfortunately there is really no good tv to buy these days. Seems like they're all crap. If not Samsung your just buying another pieces of shit from another brand.