Replacing AS15-F did not fix solarized image

[binsonk]

My Samsung LN37A550P3F_A (June 2008) flat panel TV is showing a solarized image. This is the only thing wrong with it, as far as I can tell. Based on my research I replaced the gamma IC, AS15-F Channel Voltage Buffer on the T-Con board. Or rather, by trading favors, I had a competent colleague remove and replace the chip using special equipment for surface mounting. After the repair, the solarized image persists, and if anything, got worse. What can be deduced from this?
a. The problem is elsewhere, not the gamma IC
b. The chip is DOA
c. The chip is improperly installed
a. What else might cause the image to be solarized? Is there another component on the T-Con board that might cause a solarized image? Would replacing the T-Con board fix this issue with good certainty?
b. If the chip were DOA, would the image be solarized, as before? Could I remove the chip from the board and observe the solarized image? In other words, would I be seeing the same solarized image if the chip were DOA?
c. Same query as b. If the chip were improperly installed, would the image still be solarized?

I am discouraged with troubleshooting the T-Con board. Barring a quick fix with high probability of success, I will likely replace the entire T-Con board if I can be reasonably sure of success. Where would be a good place to find and purchase such a replacement?

T-Con part numbers: AUO 55.37T04.C02 or SKU sj-55.37T04-C02

[mmartell]

Re: Replacing AS15-F did not fix solarized image

Check the voltage points with a meter and report back with them. If the graph is bad then the chip or the way in which it was replaced is still bad.

[Glitcher]

Re: Replacing AS15-F did not fix solarized image

If one of the legs on the chip is not soldered on properly, it would still cause the image to be solarized, probably not in the same degree as the original though, but still solarized.

[Caleb]

Re: Replacing AS15-F did not fix solarized image

Seen several threads of DOA AS15 chips lately, Check voltages as mmartell advised. A loose or corroded lvds can also cause this, or possibly failing tab bonds
If your set on a new tcon ShopJimmy has them in stock, kinda pricey though.

[budm]

Re: Replacing AS15-F did not fix solarized image

1 out 5 replacement AS15 ICs I get from EBAY is bad.

[binsonk]

Re: Replacing AS15-F did not fix solarized image

Please provide data sheet for AS15-F voltage points. Or do I take 48 readings? Unfortunately, there is a large frame bar nearly on top of this chip. I don't have a microscope to examine the solder job, but it looks pretty good with a magnifying glass.

[tibimakai]

Re: Replacing AS15-F did not fix solarized image

I would go over the pins again, it happened to me before. The second time going over, with the soldering it fixed the problem.

[Ltank]

Re: Replacing AS15-F did not fix solarized image

I buy AS15-F from China, usually takes just over two weeks to get parts. Heck it is cheaper to get parts from China than across the US. Whats wrong with this picture? Odd that Digi-Key or Mouser does not sell them.

[budm]

Re: Replacing AS15-F did not fix solarized image

binsonk: you need to take the DCV at the test points for GAMMA voltage readings, they should be labeled VGMA1, VGMA2,......

[budm]

Re: Replacing AS15-F did not fix solarized image

As you can see, around top right by the connector J1, you can see a bunch of test pads with
VGMA1~22.

http://www.shopjimmy.com/media/catal...37t04c02_1.jpg

[binsonk]

Re: Replacing AS15-F did not fix solarized image

I ordered a replacement T-con board, installed it. Result: No image. The lamp or backlight of TV is full on, audio is fine, but no image. I let TV run for an hour, with no change. Then turned TV off and on several times, occasionally producing a set of vertical lines covering a total width of 1 inch or so, located left of center. Mostly, the screen remains blank. I have re-seated the two ribbon cables to T-con board maybe 5 times. Don't know what else to do.

[budm]

Re: Replacing AS15-F did not fix solarized image

What DC voltage do you get at the T-CON SMD fues, check both ends of the fuse for dc Voltage.

[tom66]

Re: Replacing AS15-F did not fix solarized image

I ordered the T-com card, installed it. Result: No image. The lamp or backlight is full on, audio is fine, but no image. I let it run for an hour, with no change. Then turned TV off and on several times, occasionally producing a set of vertical lines covering a total width of 1 inch or so, located left of center. Mostly, the screen remains blank. I have re-seated the two ribbon cables to T-com card maybe 5 times. Don't know what else to do.

Try with old T-con and see if you get original solarised picture, will confirm new board is bad, some people do not thoroughly test their boards.

[Shinju]

Re: Replacing AS15-F did not fix solarized image

Sounds like a bad panel/tab bond issue.

[binsonk]

Re: Replacing AS15-F did not fix solarized image

@tom66
The AS15-F chip is now completely missing on the old T-Con board. Does this change your recommendation?

@budm
Is this SMD fuse in the bottom left quadrant of the board, about 1.75" from left edge, 0.5" from bottom edge, labelled "AVDD F1" ? There's another F1 in the bottom right quadrant of the board, 2.25" from right edge, 0.25" from bottom edge, a white-colored component with "K" on top. Where is the SMD fuse on the board?

[tom66]

Re: Replacing AS15-F did not fix solarized image

Yes, it probably would not work without AS15-F.

[Shinju]

Re: Replacing AS15-F did not fix solarized image

@tom66
The AS15-F chip is now completely missing on the old T-Con board. Does this change your recommendation?

If you want to solider the old one back on, otherwise you might need to find another board.

[stj]

Re: Replacing AS15-F did not fix solarized image

datasheet

[binsonk]

Re: Replacing AS15-F did not fix solarized image

The voltage across the component (SMD fuse?) with "K" on top reads 0.015 VDC, with TV turned on, of course.

[tom66]

Re: Replacing AS15-F did not fix solarized image

You shoulfd check both ends with black lead on chassis ground, red on fuse.