Samsung LE37B554M2PXXN. Color problem.

[Moreno83]

I picked this 1 up together with the LG plasma and this 1 has a problem.
When it starts up ( cold) the screen is fine for a few secs and then it changes to less bright and then it goes like the screen as you can see on the pictures.
The snow signal changes from black white to yellow/black.

When i press menu or source the option menu is barely visible. It can show red + green. For example the words "HDMI 1 " is red colour.

My guess is T-con or backlight?

[DemonBG]

Re: Samsung LE37B554M2PXXN. Color problem.

the fact that it gets less bright MIGHT suggest this is a power board issue (Check caps) but also could be T-con / Panel as well...

Can you post a clear picture of the PSU as well please?

Good luck,
Demon

[Moreno83]

Re: Samsung LE37B554M2PXXN. Color problem.

Hi Demon ,

Thx for the reply! The second picture is the power supply , all caps look good.
Ill try to get a more clear picture.

[Moreno83]

Re: Samsung LE37B554M2PXXN. Color problem.

This is the power supply

[tom66]

Re: Samsung LE37B554M2PXXN. Color problem.

T-con board, check gamma voltages.

[Moreno83]

Re: Samsung LE37B554M2PXXN. Color problem.

Will do that tomorrow.

[Moreno83]

Re: Samsung LE37B554M2PXXN. Color problem.

I might first try to reseat all the cables.
T-con boards , are they repairable? Or should i just replace the board?

What about cleaning the cables with WD40? Sometimes the picture is also flickering.

[tom66]

Re: Samsung LE37B554M2PXXN. Color problem.

If you have a gamma chip fault, yes, they're repairable, it costs very little. Post a picture of your T-con board.

[Moreno83]

Re: Samsung LE37B554M2PXXN. Color problem.

Not possible right now , im at work.
Will do that after 5.

[Moreno83]

Re: Samsung LE37B554M2PXXN. Color problem.

I wanted to measure gamma but i dont see the gamma chip? No words with gamma....

Ps the picture is now black with some red spots.
You dont think its PS?

[Moreno83]

Re: Samsung LE37B554M2PXXN. Color problem.

Sometimes i see the menu flash... Bright, less bright
Its fading slowly to dark

[tom66]

Re: Samsung LE37B554M2PXXN. Color problem.

Test points marked VG1, VG2, ... up to VG22. Check each voltage and report back, not all will be available.

[flocko]

Re: Samsung LE37B554M2PXXN. Color problem.

Test points for gamma voltage marked VG1<->VG22 they are a little scattered across the top of the board (black probe to T.Con fixing screw ,red to test point meter set to 20v DC) and list
VG1xx
VG2xx
VG3xx and so on Flocko

[Moreno83]

Re: Samsung LE37B554M2PXXN. Color problem.

VG1 : 7.54
VG2 : 7.54/55

VG : 4 = 7.43
VG : 12 = 11.73
VG : 13 = 11.87
VG : 14 =
VG : 15 = 8.02
VG : 17 = 12.21
VG : 18 =
VG : 19 = 12.19
VG : 21 = 0.90
VG : 22 = 0.34

These were the first that i found on the board but i already noticed that its not good right?
Is this a cap problem or the chip?

[tom66]

Re: Samsung LE37B554M2PXXN. Color problem.

The gamma chip is bad. (AS15 on T-con.) Common fault.

[Moreno83]

Re: Samsung LE37B554M2PXXN. Color problem.

Ok thx, will order new tcon.

[tom66]

Re: Samsung LE37B554M2PXXN. Color problem.

AS15-F can be replaced with hot air gun.

[Moreno83]

Re: Samsung LE37B554M2PXXN. Color problem.

Hmm ok will try that first! What about reflow?

[tom66]

Re: Samsung LE37B554M2PXXN. Color problem.

IR reflow would work, but not global reflow. What do you mean? You will have to remove the chip and install a new one, the chip is about 3 euros.

[Shinju]

Re: Samsung LE37B554M2PXXN. Color problem.

Very rare do those power supply/inverter boards have failed caps, they mostly fail due to bad inverter transformers for FYI.

I have several of those on hand, each one of them has failed via transformer/s.


As you have already uncovered your gamma is bad. Just watch out for these transformers, if you hear a Bzzzzzz or notice one is getting hotter then the other I would replace it ASAP before it burns up and possible burns a hole in the board ect.

Just an FYI for future maintenance!