Hi guys,
I've been reading over this problem on this site and others for a while but I cannot seem to fix it. I bought this tv off of ebay broken and the guy said that it would not light so I decided to take a look. When I opened up the tv one thing that jumped out at me immediately was that some of the caps and transformers on the inverter boards looked like they had been touched up or re-soldered. So out of impulse i bought another LCD inverter board. once the board came I popped it in but no luck. So I downloaded the service manual and started to read and troubleshoot. So He's my problem.
1. I found that fuse f2 (3 amps) on the mainboard was blown so i soldered in a replacement. Once I replaced it, I managed to get the LED logo light to go from orange to white, and I hear the power supply relay click on. I can also hear the mosfets buzzing and switching so I feel like the power supply is working. I can measure all the output voltages listed on the board. 5v, 12v
2. I plugged in the video cable for my laptop just to make sure it wasn't in power saving mode.
3. Now that I have power to the main board I can measure the linear regulators. All except for one of them are in range except the 1.8v supply which is at ~1.95, but I kinda think it either the way I'm measuring it or my meter that will explain the 0.05 difference. The back light still does not turn on.
4. I checked u33 like everyone else here has suggested, but my board (0171 2272 2133) looks different. There's also a yellow sticker that says 3642-0012-0150 (3c). The sticker on the flash memory says gv42l 82mp02. u33 on mine is exactly like in the manual... an 16 pin multiplexer. The only related chips I find on the board are:
u1 - p624h (or IRF7316) - Power Mosfet
u2 - p624h (or IRF7316) - Power Mosfet
u3 - p624h (or IRF7316) - Power Mosfet
u4 - abf602 - Regulator -
u5 - amc1117 - Regulator -1.943v
u6 - abf602 - Regulator -3.311v
u7 -
u8 - abf602 - Regulator -
u9 - axh549 - Regulator -
u10 - axh549
u11 - Mediatek CPU
*edit* I looked up the resistors on u5 and they r1=50 and r2=100 with Vin being 3.3v. so that voltage might be off. Can someone check my math?
5. In the manual is says to check j7 pin 14 which is the backlight on pin. when I read that it's at 0v. Could this be the cause of my problem, or just a symptom?
Thanks guys,
I'm gonna pull that regulator and check it out in the mean time.
I've been reading over this problem on this site and others for a while but I cannot seem to fix it. I bought this tv off of ebay broken and the guy said that it would not light so I decided to take a look. When I opened up the tv one thing that jumped out at me immediately was that some of the caps and transformers on the inverter boards looked like they had been touched up or re-soldered. So out of impulse i bought another LCD inverter board. once the board came I popped it in but no luck. So I downloaded the service manual and started to read and troubleshoot. So He's my problem.
1. I found that fuse f2 (3 amps) on the mainboard was blown so i soldered in a replacement. Once I replaced it, I managed to get the LED logo light to go from orange to white, and I hear the power supply relay click on. I can also hear the mosfets buzzing and switching so I feel like the power supply is working. I can measure all the output voltages listed on the board. 5v, 12v
2. I plugged in the video cable for my laptop just to make sure it wasn't in power saving mode.
3. Now that I have power to the main board I can measure the linear regulators. All except for one of them are in range except the 1.8v supply which is at ~1.95, but I kinda think it either the way I'm measuring it or my meter that will explain the 0.05 difference. The back light still does not turn on.
4. I checked u33 like everyone else here has suggested, but my board (0171 2272 2133) looks different. There's also a yellow sticker that says 3642-0012-0150 (3c). The sticker on the flash memory says gv42l 82mp02. u33 on mine is exactly like in the manual... an 16 pin multiplexer. The only related chips I find on the board are:
u1 - p624h (or IRF7316) - Power Mosfet
u2 - p624h (or IRF7316) - Power Mosfet
u3 - p624h (or IRF7316) - Power Mosfet
u4 - abf602 - Regulator -
u5 - amc1117 - Regulator -1.943v
u6 - abf602 - Regulator -3.311v
u7 -
u8 - abf602 - Regulator -
u9 - axh549 - Regulator -
u10 - axh549
u11 - Mediatek CPU
*edit* I looked up the resistors on u5 and they r1=50 and r2=100 with Vin being 3.3v. so that voltage might be off. Can someone check my math?
5. In the manual is says to check j7 pin 14 which is the backlight on pin. when I read that it's at 0v. Could this be the cause of my problem, or just a symptom?
Thanks guys,
I'm gonna pull that regulator and check it out in the mean time.
