Insignia NS-55E560A11 LED - White screen, menu barely visible

[fuxxy]

Insignia NS-55E560A11 - 55 Inch LED TV

Unit powers on, displays a white screen, Menu is displayed but barely visible.

I've read that this could be caused by the "Gamma IC" on the T-Con. Upon disassembly, I noticed that the shield around the T-Con was physically damaged, from using improper screws in the stand mount. I straightened the mount, and took pictures. I reassembled the unit and powered it on, still exhibiting the same symptoms.

Does this assumption seem valid to you guys? The IC labeled "RT8908GQW" is interesting.

Please ignore the dark horizontal lines in the pictures of the display - it's the camera, not the display.

[fuxxy]

Re: Insignia NS-55E560A11 LED - White screen, menu barely visible

Shopjimmy.com has a bunch of "compatible" replacement boards on their site.
http://www.shopjimmy.com/samsung-lj9...-con-board.htm

Where are they getting the LJ94 number? I dont see it anywhere on the board. Are those boards that interchangable that there are 15 possible substitutes?

[tom66]

Re: Insignia NS-55E560A11 LED - White screen, menu barely visible

Can you see any place with VGMA or VGAM next to it (on the t-con), like a sequence of voltage test points?

[fuxxy]

Re: Insignia NS-55E560A11 LED - White screen, menu barely visible

Near the Right FPC connector, what appears to be VGMA10, 11, 12, 13, 14, 15, 16, 17, 18

[tom66]

Re: Insignia NS-55E560A11 LED - White screen, menu barely visible

Ah, looks like the VGMA test points are all the ones after STV, which is the 4th from the right. Test each of these by measuring the voltage with respect to ground. The VGMA9 thru VGMA1 also needs to be found, I think they're the right most 9.

[fuxxy]

Re: Insignia NS-55E560A11 LED - White screen, menu barely visible

Let's hope I got these right:

VGMA1 - 14.43
VGMA2 - 12.78
VGMA3 - 12.19
VGMA4 - 11.78
VGMA5 - 11.32
VGMA6 - 10.68
VGMA7 - 10.28
VGMA8 - 9.98
VGMA9 - 7.94


VGMA10 - 6.78
VGMA11 - 4.73
VGMA12 - 4.43
VGMA13 - 4.02
VGMA14 - 3.39
VGMA15 - 2.94
VGMA16 - 2.5
VGMA17 - 1.91
VGMA18 - 0.288

[tom66]

Re: Insignia NS-55E560A11 LED - White screen, menu barely visible

Those gamma voltages look OK, although not perfect. If you heat up the gamma chip, do you notice any substantial change in those voltages?

[fuxxy]

Re: Insignia NS-55E560A11 LED - White screen, menu barely visible

Did not observe any significant change when measuring a random VGMA test point while heating gamma IC. Voltage went down a tenth of a volt or two.

VGMA1 - 14.42
VGMA2 - 12.77
VGMA3 - 12.19
VGMA4 - 11.78
VGMA5 - 11.31
VGMA6 - 10.67
VGMA7 - 10.29
VGMA8 - 9.97
VGMA9 - 7.94

VGMA10 - 6.78
VGMA11 - 4.73
VGMA12 - 4.43
VGMA13 - 4.02
VGMA14 - 3.39
VGMA15 - 2.94
VGMA16 - 2.50
VGMA17 - 1.91
VGMA18 - 0.288

[tom66]

Re: Insignia NS-55E560A11 LED - White screen, menu barely visible

I couldn't put my fingers on it, but I can now see that the voltages are OK. Symmetrical about VCOM, as they should be... I had to plot them to believe it.
Next, check the VGH and VGL voltages.
Consider a bad main board or panel.

[fuxxy]

Re: Insignia NS-55E560A11 LED - White screen, menu barely visible

Hmm. VGH and VGL are located on the T-Con? I couldn't find them.

I did find these, if they are any help:

AVDD - 15.1
VOFFE - -14.81
VONE - 27.7
VSS - -7.49
VCC12 - 1.222
VREF U_H - 14.43
VREF U_L - 7.94
VREF L_H - 6.79
VREF L_L - 0.316
VR - 7.33

At what point would you consider just walking away? I don't want to take up any more of your time than necessary

[tom66]

Re: Insignia NS-55E560A11 LED - White screen, menu barely visible

My error, Samsung/ChiMei panel: VOFFE = VGL. Your problem is VOFFE. Should measure around -6 to -8V. Replacing t-con could fix issue. Can you get a picture around the area of the t-con where VOFFE testpoint is? I had one recently like this, but it was a dark image with random white lines problem.

[tom66]

Re: Insignia NS-55E560A11 LED - White screen, menu barely visible

Please also check if VSS is positive or negative. It should be same as VCOM, or about half AVDD.

[fuxxy]

Re: Insignia NS-55E560A11 LED - White screen, menu barely visible

https://www.badcaps.net/forum/attach...9&d=1385331865
Top right, next to the two big SMD caps.

I'm at work, will be able to double check in the morning.

All my measurements were with black probe wedged in a mounting screw hole. I'll def take another look!

VOFFE is generated from within the T-Con? Or does it come from another board?

[fuxxy]

Re: Insignia NS-55E560A11 LED - White screen, menu barely visible

VSS is definately -7.49

I also tested VOFFE again, it started out around -18V, and slowly (within 2 or 3 minuites) dropped to -17V. It was still decreasing when I turned off the set.

[tom66]

Re: Insignia NS-55E560A11 LED - White screen, menu barely visible

Hmm, I am wondering if VSS is what VOFFE should be (after regulation.) There's a transistor QP3, it looks like a linear/LDO regulator but it's not, can you get the voltage on each pin and the part # of it?

[fuxxy]

Re: Insignia NS-55E560A11 LED - White screen, menu barely visible

Transistor QP3

In the image:
top pin = 15.5 mV

Left leg - (-6.8V)
Center Leg - (15.1mV and falling, slowly)
Right Leg - (-7.49V)

[tom66]

Re: Insignia NS-55E560A11 LED - White screen, menu barely visible

That looks OK now. It could be a panel fault or some other issue with the t-con, but I'm not sure because it looks OK.

[fuxxy]

Re: Insignia NS-55E560A11 LED - White screen, menu barely visible

I"m about 90% sure it's the T-Con, as when I got the set, the wrong bolts were used to secure the stand and were screwed into the T-Con shield and most likely shorted the board.

Shopjimmy shows the board as a LJ94-03528D , but I dont see that number anywhere on my board. My board is labelled S3528D0E0BTM, how can I find out if others are compatible? Shopjimmy suggests about 10 others

[tom66]

Re: Insignia NS-55E560A11 LED - White screen, menu barely visible

That's probably Samsung's internal part #, but most part retailers will use what is printed on the board.

[budm]

Re: Insignia NS-55E560A11 LED - White screen, menu barely visible

I would also use the LCD panel number to narrow down the match.