Monday, July 25, 2011

PHILIPS 37PF9431D dead, power board 310432838621 not producing output voltage

Coppell TV Repair for long offers a repair service for the above mentioned power board, but today I've got a board with a problem that I have not seen before so I decided to share it so that those blog followers who wouldn't anyway pay for a service at least get a chance of doing it right by themselves :-)

Symptom: When connected to power, the board clicks periodically about once every second - not a relay click, but an electric click as of a toroid on overdrive only more quite and nicer. Like it's trying to start and failing.

Problem: it turned out transistor 7006 had failed. Drain-Source was shorted and so the transistor had to be replaced. This is the beast in reference:

It is STP15NK50ZFP SuperMESH MOSFET  - 500V / 14A - and since we couldn't find one handy we used a substitute replacement.

Here is how it looked after the replacement:

Note the insulation barrier behind the replacement - if you do something like that you will need to have one too since the original is in plastic TO-220 corpus whereas the replacement is in TO-247 has metal back electrically connected to the drain (or source, whatever).

We checked for other damages on the board and when we couldn't find any we connected to power and voila, it worked like a charm!

If you happen to have the same problem and can't find the appropriate replacement, below is a chance to get what we used at what we call reasonable price (especially considering you've got the whole solution laid in front of you):