LN40B530P7NXZA gamma IC?

[DLinkOZ]

Working on a TV for a family member, and according to their description it seemed like the typical gamma IC issue on the t-con board (that I've read about here). Seeing it in person, I'm not so sure. Seems that after a factory reset, it does look like what I would expect with the gamma IC being faulty. However, bringing up the service menu changes it drastically. First two pics are normal operation. Third is the same settings, but in the service menu. Fourth is when I change the LVDS to the non-default setting.

Does this look like the gamma IC, or something more sinister?

[DLinkOZ]

Re: LN40B530P7NXZA gamma IC?

Here's a pic after restarted out of the service menu. Hard to tell, but there's noise in the darker areas and the top/bottom bars are far from black.

[tom66]

Re: LN40B530P7NXZA gamma IC?

No, looks like panel option wrong. What happens when you change panel option?

[DLinkOZ]

Re: LN40B530P7NXZA gamma IC?

How do I change the panel option? Is that different than the LVDS setting?

[DLinkOZ]

Re: LN40B530P7NXZA gamma IC?

I found where I have a "Panel type" setting, however I'm unable to change it.

[DLinkOZ]

Re: LN40B530P7NXZA gamma IC?

As seen, overlaying the menu seems unaffected by whatever is causing the problem. Updating the 1013 firmware to 1021 also had no changes (didn't expect it to, however I had to try).

[DLinkOZ]

Re: LN40B530P7NXZA gamma IC?

After the firmware update, the 8<p in the panel menus (two posts up) turned into an 8 with the typical up/down triangles. I did find another menu where I was able to cycle through panel types, however none of them resolved the issue.

[DLinkOZ]

Re: LN40B530P7NXZA gamma IC?

Per another thread where you found suspect voltages on the VGMA1-22 test points on the same t-con, I went ahead and tested. I do see a few dips and bumps in the voltages, whereas I believe they should be a steady ramp down:

VGMA1 - 15.59
VGMA2 - 15.39
VGMA3 - 15.26
VGMA4 - 12.98
VGMA5 - 13.36
VGMA6 - 13.84
VGMA7 - 11.24
VGMA8 - 9.99
VGMA9 - 14.15
VGMA10 - 14.63
VGMA11 - 7.93
VGMA12 - 7.01
VGMA13 - 6.69
VGMA14 - 6.58
VGMA15 - 5.60
VGMA16 - 5.35
VGMA17 - 4.82
VGMA18 - 3.96
VGMA19 - 3.23
VGMA20 - 1.84
VGMA21 - 1.77
VGMA22 - 1.56

Are those as improper as they seem to me?

[DLinkOZ]

Re: LN40B530P7NXZA gamma IC?

I'm a visual person, and this slope of the GMA voltages just isn't happy.

[Hombre]

Re: LN40B530P7NXZA gamma IC?

I am not an expert but it seams that voltages are bad. They supose to go from higher to lower and yours are a bit messed up (VGMA7,8,9,10)
I recently changed an AS15-F IC on t-con, and that solve an similar issue on my Philips with AUO panel (picture would after few minutes become as the one on your 4 picture in first post).

[willyam1]

Re: LN40B530P7NXZA gamma IC?

Defe.ntly ic gamma is bad touch with your finger you will fill it very hot. Change it tv will be fine.
Willyam1

[DLinkOZ]

Re: LN40B530P7NXZA gamma IC?

Yeah, definitely looking like it even though the picture abnormalities aren't typical. Haven't soldered surface mount ICs since the mid 90s, and I live just a short drive from Coppell, so I'll probably just hit them up to repair the board for me and call it a day.

[tom66]

Re: LN40B530P7NXZA gamma IC?

Definitely bad gamma voltages. Here is what working ones should plot out like. Note the symmetry around 7.5V.

[DLinkOZ]

Re: LN40B530P7NXZA gamma IC?

Thanks, everyone! I'll drive the t-con board over to Coppell one day this week and get the TV sorted out.

[DLinkOZ]

Re: LN40B530P7NXZA gamma IC?

Good news, everyone! Got the board repaired and life is good. Coppell TV Repair is super-easy to deal with. I dropped my board off, and ran to Best Buy to do a bit of shopping. While in the checkout lane, got a voicemail saying my board was done. $50 later this TV is back among the living. As always, thanks to everyone who helped confirm the problem!

[budm]

Re: LN40B530P7NXZA gamma IC?

Good to hear that it is fixed. BW, what is the IC number that he replaced?

[DLinkOZ]

Re: LN40B530P7NXZA gamma IC?

I don't know the entire number, but it's that damned S15 IC.