Picture still white after AS15 replacement on T370HW02 T-con

[Dannyx]

Good day folks. I've had this issue once in the past, so I was hoping it'd be a one-off incident, but unfortunately it's happened again today: a Samsung TV had a white washed-out picture, so naturally I replaced the AS15f gamma IC (or rather my workmate did, but let's pretend it's "me" here ), but it didn't change anything - the picture is exactly the same as before. I wrote a post about this before but never managed to track down the issue due to lack of time and the fact that I had to return the TV shortly. This determined me to find a cure for this once and for all, or at least know whether I should struggle or just replace the whole board whenever this happens.

Could there be something else that's immediately killing the AS15f and causes the problem to reappear ? I know the first thing to check in this case would be the gamma voltages, but sadly I can't do that now since my mate already returned the TV after giving up, but has anybody else been in this situation where replacing the gamma IC doesn't fix the issue and if so, what are other potential causes ? Perhaps others have found other components that need replacing when this happens.....the more you learn..... The T-con looks like THIS and is that same model (didn't take a picture myself so I swiped one from around here somewhere). Cheers.

[dskall]

Re: Picture still white after AS15 replacement on T370HW02 T-con

Would have been nice to know gamma. I have heard people say they had defective new chips and had to replace to get working

[diif]

Re: Picture still white after AS15 replacement on T370HW02 T-con

The times I've seen no change in the pic after fitting a new AS15 have been down to a bridged pin, overheated chip due to to much reworking and heat pad not replaced after replacing the AS15.
Redid the chips and replaced the thermal pad and all was good again.

I've noticed some TVS and tcons have a thermal pad on the AS15 and some do not.

[jetadm123]

Re: Picture still white after AS15 replacement on T370HW02 T-con

Fortunately, these chips are low cost and it's probably worth it to try replacing it again.

[Dannyx]

Re: Picture still white after AS15 replacement on T370HW02 T-con

Would have been nice to know gamma. I have heard people say they had defective new chips and had to replace to get working

Of course, there's a possibility that the chip was faulty, even though it came from the same reel as all of the others which worked perfectly...

[diif]

Re: Picture still white after AS15 replacement on T370HW02 T-con

The chip i replaced that I thought had been killed to to much rework could have been faulty. They do seem sensitive to heat though.
I've always been successful second go. You(your mate) shouldn't have given up so easily.

[Dannyx]

Re: Picture still white after AS15 replacement on T370HW02 T-con

He does like to overheat things indeed...keeping his hot air gun on 450c all the time, thought I believe he always heats parts from underneath if possible.

[dskall]

Re: Picture still white after AS15 replacement on T370HW02 T-con

This is a little after the fact since nothing can be checked or replaced.

[attainteddragon]

Re: Picture still white after AS15 replacement on T370HW02 T-con

i had a samsung recently that looked like an as15 failure.

replaced the chip and fault was still there.

checked gamma voltages and they looked good.

disconnected one half of t-con and was the same, did other half and the pic was good.

removed bezel and screen cover to find that the panel driver boards were on the bottom and someone must of over wet the screen while cleaning. several caps were damaged, tracks were decayed and i couldn't save that one.

so driver board issues can look like as15 faults.

check gamma voltages when you can to confirm the chips operation.

[tibimakai]

Re: Picture still white after AS15 replacement on T370HW02 T-con

Once, I had knocked off a small pot on the lcd board. That was causing the white screen for me.

[Dannyx]

Re: Picture still white after AS15 replacement on T370HW02 T-con

Once, I had knocked off a small pot on the lcd board. That was causing the white screen for me.

LCD board.....would that be the t-con or the buffer boards under the bezel ?

[tibimakai]

Re: Picture still white after AS15 replacement on T370HW02 T-con

...under the bezel. This can happen, if you take the screen off and when you place it back, you can knock off the little pot.

[neilc6]

Re: Picture still white after AS15 replacement on T370HW02 T-con

I am fairly convinced that sometimes a whitewashed screen could be caused by something other than the AS15F on the tcon.

I had a LN40A530P1F that I replaced the the AS15F 4-5 times from two different batches of chips. I ended up buying a new tcon board that fixed it.

I currently have a LN37B530P7F. Replaced with AS15F and RM5101 from two different vendors and same issue. Soldering and pin alignment look perfect. Have just ordered a new tcon for this TV as well.

[neilc6]

Re: Picture still white after AS15 replacement on T370HW02 T-con

Got a "new" tcon board on ebay and the whitewashed screen is still there. Suspect there is a fault in the panel.

[Andrew F. Ali]

Re: Picture still white after AS15 replacement on T370HW02 T-con

Yes I have spent/wasted time and money on a few TVs like that already, but I have learned. I was going to say that from the beginning of this thread but did not want to pre-empt anyone. There are certain voltages on the T-CON Bd. that if correct and a picture should show, if the LVDS signals are present then it concludes that the Panel is bad.