Samsung LN37A450C1DXZA - Gamma chip problem?

[caphair]

I measure:

XPOL 1 - 1.66v
XSTB_1 - 0.19v

1 - 15.16
2 - 14.96
6 - 10.45
7 - 9.77
8 - 9.70
10 - 7.75
11 - 7.48
12 - 6.72
13 - 6.45
15 - 4.75
16 - 4.45
17 - 3.92
21 - 0.49
22 - 0.35

If it's a bad gamma chip, which one on the board would it be?

[Glitcher]

Re: Samsung LN37A450C1DXZA - Gamma chip problem?

It should be that chip underneath the pad. AS15

[caphair]

Re: Samsung LN37A450C1DXZA - Gamma chip problem?

It should be that chip underneath the pad. AS15

Does it seem like that's the issue?

[tom66]

Re: Samsung LN37A450C1DXZA - Gamma chip problem?

Could be - very common on these models. Voltages look ok but they can be bad wthout always being obvious.

[caphair]

Re: Samsung LN37A450C1DXZA - Gamma chip problem?

Could be - very common on these models. Voltages look ok but they can be bad wthout always being obvious.

Any sure way to know without direct chip replacement?

[tom66]

Re: Samsung LN37A450C1DXZA - Gamma chip problem?

Does the chip run very hot? Burn-like temperatures...

[caphair]

Re: Samsung LN37A450C1DXZA - Gamma chip problem?

Does the chip run very hot? Burn-like temperatures...

Odd, I removed the foam pad and the picture looks normal now. It'll occasionally change like before but it's not constant

[caphair]

Re: Samsung LN37A450C1DXZA - Gamma chip problem?

Does not run very hot no. Slightly warm

[tom66]

Re: Samsung LN37A450C1DXZA - Gamma chip problem?

Wait for it to go wrong and check voltages again, there have been a few cases of intermittent AS15F.

[caphair]

Re: Samsung LN37A450C1DXZA - Gamma chip problem?

Wait for it to go wrong and check voltages again, there have been a few cases of intermittent AS15F.

The original voltage postings were when it was acting up. I'll try freeze spray and probably just order the chip and swap it out. Cheap enough from China.

[caphair]

Re: Samsung LN37A450C1DXZA - Gamma chip problem?

Update: replaced the chip and same problem persists

[caphair]

Re: Samsung LN37A450C1DXZA - Gamma chip problem?

Would it still be a tcon issue or mainboard?

[tom66]

Re: Samsung LN37A450C1DXZA - Gamma chip problem?

Check voltages again, if bad you got a dodgy chip and you may need to try again with a new chip, or sometimes soldering it just right can take some work.

[saddle_au]

Re: Samsung LN37A450C1DXZA - Gamma chip problem?

Check the soldering on the AS15 for shorts, but if the symptom is exactly the same, go back and check the voltage references and generator.

Check the gamma reference U201 both input and output.

Check Q101, D102, and the dual barrier diodes D104, D105.

[caphair]

Re: Samsung LN37A450C1DXZA - Gamma chip problem?

Fixed: it was a bad replacement chip. Tried another and all is well.