Samsung LCD TV has Very Bright Picture - LN40A500T1FXZA

[TubeJunkie]

Hi. I have a Samsung LCD tv that has a very bright picture. I've tried the picture reset in the menu, did'nt help. It powers on normally. Has good sound. I've taken the back off, and inspected it. I did not find any burnt parts or bulging caps. Any advised will be greatly appreciated. Thanks.

[aaronwt6]

Re: Samsung LCD TV has Very Bright Picture - LN40A500T1FXZA

Well, without any testing my first guess would be the tcon board. Let some other people with a bit more experience chime in but if that's the problem it should be a cheap fix.

[tom66]

Re: Samsung LCD TV has Very Bright Picture - LN40A500T1FXZA

I would say t-con gamma IC.

[budm]

Re: Samsung LCD TV has Very Bright Picture - LN40A500T1FXZA

I second that it has Gamma IC problem.

[smason]

Re: Samsung LCD TV has Very Bright Picture - LN40A500T1FXZA

Interesting. One of my Samsungs used to do that for about 1 minute, a few times a week at random. Not quite that bright though.
Hasn't done it for a quite a while now.

[TubeJunkie]

Re: Samsung LCD TV has Very Bright Picture - LN40A500T1FXZA

I ordered a brand new T-Con board, but the problem did NOT change. Any other suggestions? Thanks

[tom66]

Re: Samsung LCD TV has Very Bright Picture - LN40A500T1FXZA

I would suggest testing the gamma voltages first, to see if the T-con you have is defective ("brand new"? or "used from scrapped TV"?). If it is not, then it is probably panel. A small chance the main is bad.

If you need help testing the gamma voltages, post a close shot of the T-con.

[TubeJunkie]

Re: Samsung LCD TV has Very Bright Picture - LN40A500T1FXZA

Here is a pic of the T-con board. The board I purchased, was brand new. And yes, I would like to test the gamma voltages. Thanks.

[tom66]

Re: Samsung LCD TV has Very Bright Picture - LN40A500T1FXZA

Between the two white ribbon cables is a box marked GAMMA. This is your test area. On each gold pad marked with a number measure the voltage there. Red probe on test point black on chassis. DC20V range. You're expecting a monotonic (same direction) increase or decrease from 1-17, in the range of 0-15V.

[tibimakai]

Re: Samsung LCD TV has Very Bright Picture - LN40A500T1FXZA

The TV it was previously opened?
Do you see missing screws?
On one of the TVs, I took off the panel's metal frame, and when I put it back I have damaged a tiny pot on the panel's thin board. The screen looked like yours.

[TubeJunkie]

Re: Samsung LCD TV has Very Bright Picture - LN40A500T1FXZA

Hi, tom66. Here are the gamma voltage readings:

1. 15.7v
2. 14.9v
3. 12.4v
4. 11.5v
5. 11.6v
6. 12.9v
7. 13.1v
8. 9.6v
9. 8.1v
10. 7.5v
11. 11.2v
12. 7.1v
13. 8.8v
14. 8.7v
15. 8.8v
16. 3.7v
17. 2.6v

[tom66]

Re: Samsung LCD TV has Very Bright Picture - LN40A500T1FXZA

Definitely a defective gamma IC there; the voltages are all over the place.

[TubeJunkie]

Re: Samsung LCD TV has Very Bright Picture - LN40A500T1FXZA

That's what I thought when I seen the eratic voltages. This is the original T-con board. I've already returned the new board, Personally, I don't think the new board was "NEW", it had several scratches on the back of it. Should I get a different board? And Thanks for your time.

[tom66]

Re: Samsung LCD TV has Very Bright Picture - LN40A500T1FXZA

I would try that. New boards usually mean used on eBay, everyone lies it appears....

[TubeJunkie]

Re: Samsung LCD TV has Very Bright Picture - LN40A500T1FXZA

To tom66: Bought a used board from a working TV with a broken panel, and it worked perfectly. So yes, those so called "NEW" boards on Ebay are used and untested. Thank You so much for your help.

[NUTIN2LUZ]

Re: Samsung LCD TV has Very Bright Picture - LN40A500T1FXZA

I know this is an old thread and sorry to jump onto this thread, but could someone help me also?

I have these readings on the gamma:
-eBay tcon
1. 15.4
2. 13.13
3. 14.66
4. 14.29
5. 13.5
6. 11.85
7. 12.45
8. 9.34
9. 8.15
10. 6.89
11. 6.14
12. 5.56
13. 5.08
14. 4.72
15. 4.36
16. 3.45
17. 2.62

-original tcon
1. 10.53
2. 12.43
3. 11.89
4. 11.02
5. 10.6
6. 10.19
7. 9.32
8. 4.79
9. 7.5
10. 6.93
11. 6.76
12. 8.95
13. 5.65
14. 5.95
15. 4.83
16. 3.6
17. 3.11

I wanted to know what are the correct or good reading voltages. I can send pictures if needed.

[Glitcher]

Re: Samsung LCD TV has Very Bright Picture - LN40A500T1FXZA

Both tcon boards seem to be bad. There are irregular spikes in the voltages. The voltages should gradually only drop down with each prior measure.

[tom66]

Re: Samsung LCD TV has Very Bright Picture - LN40A500T1FXZA

Also, the voltages should be symmetric about the mid point of around 7.5V. Both T-cons are defective.

[NUTIN2LUZ]

Re: Samsung LCD TV has Very Bright Picture - LN40A500T1FXZA

What are good voltages?