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Sylvania (Funai) LC420SS8 power issue (no lights)    
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Joined: 31 Jan 2012
Posts: 15
Location: Torrington, WY

PostPosted: Tue Jan 31, 2012 7:33 pm    Post subject: Sylvania (Funai) LC420SS8 power issue (no lights) Reply with quote

I'm a TV tech, and I'm completely stumped, I'm hoping someone has some helpful information or advice for me. I have a TV in the shop that has no lights and won't power on. The power & standby lights are dark. From what I've seen, this is typically an issue with a Diode -- component D604. Before I even tried to replace anything component-level, I just ordered a replacement power board, and that didn't fix it. They had the inverter power board for an additional $15, so I ordered that as well. No improvement. Next, I assumed that it must be an issue with the mainboard, so I ordered that. Still no change. I've checked voltages on most of the things that I can, and I'm getting low on everything -- anything that should be 3.3V, I'm getting more like 2.2. CN500 is putting out something more like 185V rather than 345V. I would assume that I was just sent a defective power board, but in lieu of getting a replacement, I'd rather just fix this board (or the original). I've already desoldered D604 on the original power board and tested it, and it tests good on my multimeter. I don't really want to try desoldering components on the board I just got, just in case I have to send it back (actually, I already had to, because the power cord on the new board was damaged, but I'm hoping I can solder the old one back on well enough they can't tell I did that.)
Does anyone have a way to test this board to verify 100% that the primary power board is at fault? Any ideas what component could have failed?
One last piece of information -- when you unplug the TV, about a half second later, the standby light comes on for half a second, then goes out again.
Thanks a million in advance for any help you can provide. I'm really stressing over this one, and I CAN'T tell the customer I can't fix it -- I also don't want to charge the customer any more, and I don't want to pay too much out of pocket if the company that sold me this power board refuses to take it back. Worse yet, what if I'm wrong, and I buy another power board from someone else, only to find that it was a bad panel (or something else) all along?
Thank you all for any help you can provide.

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Joined: 31 Jan 2012
Posts: 15
Location: Torrington, WY

PostPosted: Wed Feb 22, 2012 4:27 pm    Post subject: End result Reply with quote

As it turns out, the retailer who sold me the power board was very courteous, and shipped me a replacement at no charge. The first one they had shipped was DOA.
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