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Samsung LE37A656A1F goes to white screen after 2 minutes!

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cheeky2:
I have a Samsung LE37A656A1F which the screen goes white after a couple of minutes.
 It has the T370HW02 V6 screen in it.
 So far i have removed tcon connectors and powered up board for around 10minutes and then reconnected after powering down to prove whether its the main board (still takes around 2minutes for screen to go white).

 So its looking down to either the TCON or the panel.
 I have heated up the individually the IC's on the tcon board without any difference.
 
 I know the AS15-F IC can fail on the tcon but normally you get solarisation of the colours, but not having much experience with this issue before i am seeking advice on the issue?

Thanks :)

zomikula:
Does it display a picture before going white.
Is the as15 chip getting hot ?
And how are the vgamma volatges.

When it goes out does the display fade out.. lighter and lighter ?

And are you saying that it goes white with out the tcon connected?

I would say the as15.. it does make the display go white too.
Normally you can see a faint image.

cheeky2:
Initially the picture of the screen is fine then gradually gets white. The AS15-F doesn't get hot and i haven't checked the voltages yet.
 What should the vgamma voltages be roughly on all test points on the tcon board? I ask as it will be easier to work out for future reference if i have a similar fault in future.
 Thanks

Turnip:
Hi Cheeky,

Usual to replace the AS15-F as always first suspect for most anything in display problems, and at less than a quid it's cheap.

Admit had a few where the screens were faulty with whiteout with not an AS15 in sight - Mostly small screen stuff with T-con incorporated into screen - Chris.

downunder:
Hi Cheeky,
Undoubtedly the gamma chip. Could be AS15 but I've come across some AS19. They are not interchangeable.

If you have VGAM test points, say VGAMA1 to VGAMA22 (usually in a group together), you should measure a gradual increase or decrease in volts in the range say 1V to 15V as you check each TP in numerical order. If one or more voltages don't fit this pattern,
the gamma IC is defective. eg 1V, 1.8V, 2.3V, 2.7V and so on is good, but 1.8V, 0.9V, 3.7V, 2.7V is bad.

The gamma IC doesn't necessarily get hot to be faulty, but in some cases it does get too hot to touch.

Bruce

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