samsung la40b650t1fxxy

[attainteddragon]

i thought this was going to be the as15-u chip, but gamma voltages seem ok.
can it fail and still give good readings, or is there anything else that i can test.

gamma voltages
294.8 mv
0.576 v
2.657 v
4.07 v
5.48 v
6.83 v
7.06 v
7.76 v
7.88 v
10.2 v
10.93 v
12.83 v
15.14 v
15.49 v

thanks guys!

[tom66]

Re: samsung la40b650t1fxxy

Those voltages do still look bad -- they jump too much. The increase should follow a smooth curve, centered around 7.5V (AVDD/2 or VCOM.)

[attainteddragon]

Re: samsung la40b650t1fxxy

ok then.
so should i change out the as chip and see how it goes?
if i take the middle voltage, should it be a fairly even gap (in voltages) in both directions from there.

[tom66]

Re: samsung la40b650t1fxxy

Ignore the horizontal axis of the graph. Your voltages should be 7.5V in the middle, and then spread out identically from there.

[attainteddragon]

Re: samsung la40b650t1fxxy

so the chip needs to go!
thanks heaps tom!
is there anything else i should know before i order the chip.

[tom66]

Re: samsung la40b650t1fxxy

Check VCOM, VGH, VGL too.

VCOM: ~7.5V (often generated by GAMMA chip too though)
VGH: +15~30V
VGL: -5V~10V

[attainteddragon]

Re: samsung la40b650t1fxxy

vgh 31.06
vgl -6.01
vcomf2 36 mv (couldnt find vcom and not sure if this is the one)

[tom66]

Re: samsung la40b650t1fxxy

I think VCOM is also bad, but it's generated by the AS15 IC. Therefore, replace that IC.

[attainteddragon]

Re: samsung la40b650t1fxxy

ill order the ic now.
it will take a few weeks till i get it, then ill report back.
thanks again tom.