I posted here a little over a year ago when I first got this TV. The original issue was blown mosfets on the power board, and a bad IPM on the Z-sustain and y-Sustain boards. I had the y-sus and z-sus boards repaired by a reputable company. I bought a "refurbished" power supply board off of eBay. That fixed the problem, although the TV would still refuse to turn on if it had just been turned off. The screen would brighten a little (if it was an LCD, I would describe this as the backlight turning on) and the power LED would blink 5 or so times.
A couple of weeks ago the...
nswizdum
Member
Last Activity: 10-22-2012, 06:24 PM
Joined: 01-19-2011
Location: Bangor, maine
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LG 50PC3d-ud blown fuse and power mosfet
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Re: LG 50PC3D-UD power issue
I did eventually get it fixed (with help from Coppell TV Repair). It was one of the MOSFETs causing my problem. I broke my rule of "no soldering after midnight". A bead of solder dripped off the MOSFET pin and shorted a connection that was hidden under the heatsink. That was what caused the sparks and blew a bunch of the MOSFETs again. Still happily using that TV now.... -
Re: LG 50PC3D-UD power issue
Upon further inspection, it appears that the fuse was blown when electricity arced from one of the mosfet solder points on the bottom of the power board, to the back of the plasma panel. I had it in the proper mounting holes, what would cause that? Some kind of overload?...Leave a comment:
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Re: LG 50PC3D-UD power issue
Well, that was fun. I powered the TV on again to check some more points, and when I started testing points, there was a really loud pop (ceramic fuse blew). 4 of the power mosfets on the first heatsink bit the dust as well. I think it may be time to buy a new power board, 4 mosfets is $40, and I still don't know what the original problem was.Last edited by nswizdum; 01-27-2011, 07:40 PM.Leave a comment:
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Re: LG 50PC3D-UD power issue
No dice, still the same problem after replacing that mosfet.Leave a comment:
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Re: LG 50PC3D-UD power issue
Yep, I have already removed it and tested it, same result.
I'm having a hard time finding a spec sheet though, are there any places I should be checking besides [url]http://english.electronica-pt.com/?[/url] I found a few people selling them on ebay, but purchasing electronic parts on ebay is a bit like purchasing prescription drugs from a street corner, no idea whats actually in it.Re: LG 50PC3D-UD power issue<br /> ...ng a hard time...Leave a comment:
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Re: LG 50PC3D-UD power issue
I took another look at the power board and found a component that may be the problem. It looks like a large voltage regulator or mosfet, it's labeled Q855 on the schematic (it connects directly to the transformer that generates the VS voltage). It shows less than 15ohms resistance between each pin, in both directions, which is different from the other similarly labeled components. Theres also a box capacitor next to it that is caved in on the sides.
The part is labeled "SD20N60" and "GAV602" on the front. I'm going to...Last edited by nswizdum; 01-23-2011, 04:38 PM.Leave a comment:
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Re: LG 50PC3D-UD power issue
So now the question is, which design do I have? This is getting interesting....Leave a comment:
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Re: LG 50PC3D-UD power issue
Also, page 59 of the troubleshooting manual states that when the YSUS board is disconnected from the power board, there will be "no display". Would that mean that the power supply should still function with that cable disconnected?
Sorry for the multiple posts, I keep missing the window for editing.Leave a comment:
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Re: LG 50PC3D-UD power issue
I pulled the YSUS board and tested the IPMs as it was described in the manual, I think. I put my meter in diode test mode and tested all the pins in the order listed, there was a decent amount of resistance between all of them, no open or shorted circuits. I also checked over the caps and mosfets for any obvious signs, didn't find anything. I'm going to look around a bit more then move on to the ZSUS board....Leave a comment:
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Re: LG 50PC3D-UD power issue
The VS and VA voltages are generated on the power board though, correct? So wouldn't the problem still be located there, and not in the IPM module? Or could the IPM module be causing the failure once it starts receiving power from the VA source(the 5v it gets up to before the tv shuts back off)?Leave a comment:
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Re: LG 50PC3D-UD power issue
Looking at the service manual, I realized that VS-ON comes from the digital board, so it would read 0v with the cable disconnected. I re-attached all the cables and tested the VA and VS pins (I am going through the "power sequence" listed in the manual to try to find where it is stopping, since I can hear the relays click, and can read 3.3V, 5V, 6V, 12V, and 19V, I know it is making it to step 3). I read 0v on VS, and VA gets to 5v before the tv turns off....Leave a comment:
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Re: LG 50PC3D-UD power issue
Scratch that, I can measure 3.3v when all cables are plugged in, it must come from one of the attached boards. Any ideas on where to proceed from here?
I should also specify that when I said all the voltages on the pins were good, I was only referring to the ones that were labled. The VS-ON pin never shows a voltage.Last edited by nswizdum; 01-21-2011, 06:19 PM.Leave a comment:
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Re: LG 50PC3D-UD power issue
Ok, I just double checked all the pins for the 800,802, and 803 connectors. All the voltages except 3.3v are still fine, and I do have 5v standby when the tv is plugged in. I'm going to wait for any residual charge to dissipate then check the mosfets in the "HS6" section of the power supply board.Leave a comment:
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Re: LG 50PC3D-UD power issue
That service manual looks like its going to be immensely useful, although my TV doesn't have a hard drive in it.
Here's a shot of the back panel....Leave a comment:
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Re: LG 50PC3D-UD power issue
Here's the pictures. I included some of the surrounding boards too. Where do I find the Chassis number on the panel? I get no service manuals for PDP50X30010....Last edited by nswizdum; 01-20-2011, 10:42 PM.Leave a comment:
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Re: LG 50PC3D-UD power issue
Thanks for the replies. I understand the problem with off-site pictures, I figured Google would be fairly trustworthy. I'll try to find a way to shrink them down.
I did hear about unplugging the y or z board, and I just tried it after posting this. I still had the same problem when unplugging all 3 cables, and when unplugging each one separately.
The full model number is PDP50X30010.DDDRBAB
I will edit this post and add in the attached pictures (if that is permitted on this forum) or I will post them in a...Leave a comment:
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LG 50PC3D-UD power issue
I recently picked up a LG 50PC3D-UD to repair. When I power the TV on, I hear the relays click, the green led on the front blinks 3 times and then goes back to red. I tried searching around a bit and found that these units have issues with the 10v 3300uf caps on the power board. All the caps look fine to me, no obvious bulging or leaking, but I replaced them anyway. The TV still wont power on fully. I found some LEDs that look like they may be error codes, and I included a picture of them. I also noticed a green and red LED under the shield on the tuner. I also tested all the pins on the p801,802,...
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