Help with Polaroid P40LED13 no picture fault.

[speccyman]

Hello badcaps community. New member here looking for advice from better knowledged folks like your good selves with a repair I'm doing on a Polaroid P40LED13 led 40'' tv with the Vestel chassis. Basically this tv powers up, goes out of stand-by fine, sound is fine, but there is no picture at all. No splash screen for the logo, or backlight either. I've tried shining a touch at the screen but still can't see anything.

So far I have removed the back off the tv and started to make some checks starting with the power supply board. The power supply is a Vestel 17IPS20 type. I'm unsure of the exact voltages I need at the connector going to the mainboard and LED's as I have not found a circuit diagram for the board yet so still need to check those further. However I have found what seems to be 2 shorted diodes at locations D100, and D506 which are both parallel to each other. Anybody know the diode type these are so I can order replacements?

Is the 2 diodes at the those locations a known fault for this? Could another failed component cause these to short?, or can it be down to the heavy use the tv got as it was on all day most days. My knowledge of repair is not great on these, first repair in fact. However I'm long-time hobbyist and handy with a multi-meter/soldering iron so don't mind getting stuck in. Cheers.

[tom66]

Re: Help with Polaroid P40LED13 no picture fault.

Most common issue on this model power supply is a shorted FET that makes those diodes look bad - you can flip the board over and check.
Replace the FET, it's a 60V device (not 30V as the schematic suggests!) and the adjacent diode.

[speccyman]

Re: Help with Polaroid P40LED13 no picture fault.

Just thought I'd update this thread to let you know the TV is now fixed and back with it's very pleased owner.

The fault was down to diode D506(MUR460 600V-4A rectifier diode) which had shorted. Although D100(RL207 1000V-2A) was showing it was shorted, it actually wasn't once removed and tested out of circuit. But have replaced both anyway.

I think the reason for the diode failing is due to the owner not switching the set off properly by unplugging from the mains whilst the TV is still on. Either that or a spike/surge in the mains power. Hope that help other's with similar fault, but it only was a couple of minutes fault finding with a test meter, and few more soldering work. Cost for repair, about 80p!