Magnavox 42MF521D/37 42-Inch

[Vizor]

Magnavox 42MF521D/37 42-Inch

History
=======
my little bro purchased This off facebook about a month ago and tried to fix it himself he replaced a few caps around 2018 but still no luck.

Symptoms
========

TV doesn't turn on, no Light nothing

Power supply comes on but chirps and gets hot at 2 p6Ke120A's

Analysis
========

1) i think the power supply may be bad.
2) not sure about the main board but it has a bunch of brown stuff all over the board.

[tom66]

Re: Magnavox 42MF521D/37 42-Inch

I believe this is caused by a shorted TVS near 12.jpg. With no power applied, check the diodes for shorts using the diode test mode of a multimeter. The diodes are the black devices with a white band, e.g. 6054.

[Vizor]

Re: Magnavox 42MF521D/37 42-Inch

Looks like all 5 of those Diodes in that picture are shorted.

[tom66]

Re: Magnavox 42MF521D/37 42-Inch

Looks like all 5 of those Diodes in that picture are shorted.

Do they read the same both ways?

[Vizor]

Re: Magnavox 42MF521D/37 42-Inch

All of them but 6066 have the same measurements both ways.

[tom66]

Re: Magnavox 42MF521D/37 42-Inch

All of them but 6066 have the same measurements both ways.

Okay, that sounds pretty shorted to me. Do you have the ability to remove the diodes, is there a part # on them?

[Vizor]

Re: Magnavox 42MF521D/37 42-Inch

p6Ke120A on 2 of them was just making sure they were shorted before ordering some new ones, suppose their is probably nothing locally to use.

[tom66]

Re: Magnavox 42MF521D/37 42-Inch

p6Ke120A on 2 of them was just making sure they were shorted before ordering some new ones, suppose their is probably nothing locally to use.

Yeah, that's most likely a Digikey thing to order:

http://search.digikey.com/us/en/prod...ACT-ND/2770358

Still, ~$5 to fix a TV... not bad...

[Vizor]

Re: Magnavox 42MF521D/37 42-Inch

gonna be a little bit more then that gonna replace all the caps just to make sure

[tom66]

Re: Magnavox 42MF521D/37 42-Inch

gonna be a little bit more then that gonna replace all the caps just to make sure

Good idea. These Magnavox PSUs kill caps like no other. I would suggest Panasonic FM or FR replacements.

[electronicsurplus]

Re: Magnavox 42MF521D/37 42-Inch

Also, we have found that even though the caps are replaced and the Diodes are not shorted. since, the diodes are fast recovery they still need replacing

Sometimes the power supply will chirp. This is coming from the Transformer not turning on due to defective Diodes. We have used ECG156 or equivalent. work perfectly and, are available at most electronic distributors. we buy them by the 100's @ .50/each

Just thought this may help a few people

[cliff_hootarski]

Re: Magnavox 42MF521D/37 42-Inch

Just repaired one of these last week. Replaced the two zener diodes 6055 and 6054, and
the 3 1500mf caps on the secondary side. Another post here mentioned that the two zeners
could be replaced with Radio Shack #276-1114 1.5A/1000v diodes. Tried that temporarily
and the set fired right up. Ordered the correct zener diodes from Digi-Key for the permanent fix.

(original symptom of the TV was the power supply chirping noise and voltage varying).

[Jonny Accelerant]

Re: Magnavox 42MF521D/37 42-Inch

I have an opportunity to buy one of these broken from craigslist, unseen. What's a fair/safe price to offer for it. If it's a matter of caps and diodes I can fix it.