Samsung LA37B530P7R color and picture quality problem

[T-con]

Re: Samsung LA37B530P7R color and picture quality problem

Hmm, well, that doesn't look quite right. But, for comparison, could you plug TV into a laptop or other computer, and try displaying a static image of, say, a gradient, or a known picture?

Ok

[T-con]

Re: Samsung LA37B530P7R color and picture quality problem

This is the first time i connected it with a desktop cpu, colors seems fine but contrast is too strong adjusting it, no good really hard to tell what the problem is, sorry...

[tom66]

Re: Samsung LA37B530P7R color and picture quality problem

Try loading this image in full screen.

[T-con]

Re: Samsung LA37B530P7R color and picture quality problem

Hi tom66,
Here it its, looks like its over contrasted, what do you think?

[tom66]

Re: Samsung LA37B530P7R color and picture quality problem

I would agree. Can you post a picture of the t-con board?

[T-con]

Re: Samsung LA37B530P7R color and picture quality problem

I would agree. Can you post a picture of the t-con board?

The tcon has a AS15HF chip

[budm]

Re: Samsung LA37B530P7R color and picture quality problem

So many failed AS15 IC. They do run warm and I see some of these have thermal transfer pad to transfer the heat to the metal shield.

[tom66]

Re: Samsung LA37B530P7R color and picture quality problem

See attachment. There are 21 or 22 VGAMMA voltages to check I believe. I have highlighted one. (This is from same t-con board but other repair.) They are labelled VG1 thru VG22. To check voltage, set digital multimeter to DC 20V. Press gold pad test point with red probe, and keep black probe on chassis. Note voltage and repeat for all 21-22 points.

Plotted in order the wave should look like the graph (may vary, but it should be monotonic, i.e. increasing or decreasing only. Any sudden spikes or shallow regions are bad. It should also range from 0-15V.)

[T-con]

Re: Samsung LA37B530P7R color and picture quality problem

So many failed AS15 IC. They do run warm and I see some of these have thermal transfer pad to transfer the heat to the metal shield.

Hi budm,
Thanks for the link, ill read thru all that if i have the time... My as15 chip has no heat sink maybe the reason why it failed....

Regards t-con

[T-con]

Re: Samsung LA37B530P7R color and picture quality problem

See attachment. There are 21 or 22 VGAMMA voltages to check I believe. I have highlighted one. (This is from same t-con board but other repair.) They are labelled VG1 thru VG22. To check voltage, set digital multimeter to DC 20V. Press gold pad test point with red probe, and keep black probe on chassis. Note voltage and repeat for all 21-22 points.

Plotted in order the wave should look like the graph (may vary, but it should be monotonic, i.e. increasing or decreasing only. Any sudden spikes or shallow regions are bad. It should also range from 0-15V.)

Thanks! tom66 ill try this and post readings....

Regards t-con

[T-con]

Re: Samsung LA37B530P7R color and picture quality problem

Hi tom66,
Here's the v measurements, sorry for the blurred picture, but as you can see there a big spike reading on vg6 and a small one on vg13, does this mean that my tcon or as15 chip needs replacement?

[T-con]

Re: Samsung LA37B530P7R color and picture quality problem

Forgot to post picture

[tom66]

Re: Samsung LA37B530P7R color and picture quality problem

Yep, definitely bad. Replace AS15 or t-con board.

[T-con]

Re: Samsung LA37B530P7R color and picture quality problem

Ok ill try to look for parts tomorrow, if i'm lucky to find one
Bdw thanks for the help, much appreciated, will post soon if i get the parts...

[tom66]

Re: Samsung LA37B530P7R color and picture quality problem

Out of interest did you record actual numbers? Could you share those? I'm building up a collection of info on this type of failure which is becoming very common.

[T-con]

Re: Samsung LA37B530P7R color and picture quality problem

Yup but my dmm i believe is not accurate its just a Chinese version but if its ok for you then here it is...

Vg1 - 15.43v
Vg2 - 15.17v
Vg4 - 12.60v
Vg6 - 14.41v
Vg8 - 10.25v
Vg10 - 7.9v
Vg11 - 7.7v
Vg12 - 6.7v
Vg13 - 7.0v
Vg15 - 4.88v
Vg17 - 4.24v
Vg19 - 2.91v
Vg21 - .53v
Vg22 - .29v

[T-con]

Re: Samsung LA37B530P7R color and picture quality problem

With a bit of luck i bought an as15-f chip, my original chip was as15-hf, question is? Is it the same with other as15-f, g, etc...

Will try replacing the old chip tommorow, and post results, fingers crossed

[tom66]

Re: Samsung LA37B530P7R color and picture quality problem

I've heard they are compatible and interchangeable.

[T-con]

Re: Samsung LA37B530P7R color and picture quality problem

A guy told me that the chip was just an op amp, so no need for compatibility, i hope so.

[tom66]

Re: Samsung LA37B530P7R color and picture quality problem

It basically is a set of precision resistors and 22 op amps in one device. Some of them even have the resistors external, I think the AS15 series does.

What appears to be failing is the op amps weren't designed to output continuous current to the panel source drivers so as the chip heats up some part of them drift either positive or negative, probably some problem with the opamp output stage or offset currents.