Magnavox 37MF337B/37

[ntehicks]

I just got this TV it works but it takes several times of turning the tv on for it to turn on and work. I have taken pictures of the power supply. looks like there is some issues a few burned spots. and several capacitors are bulging. what all would you replace?

[Shinju]

Re: Magnavox 37MF337B/37

I just fixed one of these, mine had a bad 2200uf 35v, 1200uf 35v and 2x 1000uf 35v caps replaced them all and it fired right up.

[ntehicks]

Re: Magnavox 37MF337B/37

do you think i should replaced any of the diodes. they look burned.

[johnboy1313]

Re: Magnavox 37MF337B/37

Replace the caps in the psu for sure. Have you tested the diodes?

[Shinju]

Re: Magnavox 37MF337B/37

Mine were fine, I didn't have any burnt marks like you have. I would replace everything in that was in or around and could be affected by the burnt parts.

I don't think a used power board was spendy at all if you ended up needed to replace it.

[stj]

Re: Magnavox 37MF337B/37

it's safe to say that zener diode is fucked!
and it needs to come out without damage unless there is a schematic to find out the part rating.
also the blue ceramic cap liiks a bit black on one side.

[budm]

Re: Magnavox 37MF337B/37

The blue cap C945, the Zener ZD906 (typical P6KEXXX around 200V rating), and the Diode D924 are part of the snubber network to reduce the spike to help protect that MOSFET Q908. You need to test them all.

[ntehicks]

Re: Magnavox 37MF337B/37

I picked up the TV lastnight. The tv turns on but take several try's before it will actually turn on. so I figured something was wrong. I will test the parts when I get home tonight. I figured I would just replace all in the black area just to be safe.

[budm]

Re: Magnavox 37MF337B/37

Since you are still getting the standby voltage, that STBY is still working kind off with those over heated parts, so replace the caps on the power supply board as a set, not just the domed top ones, the large main cap is probably OK.

[ntehicks]

Re: Magnavox 37MF337B/37

I have placed the order for all of the parts. I will let you know how it goes.

[budm]

Re: Magnavox 37MF337B/37

So what is the P/N of that Zener ZD906?

[ntehicks]

Re: Magnavox 37MF337B/37

for ZD906 I used P4KE250A-E3 I tested all the parts as I removed them. all of the diodes even though they were black char tested good. I replaced them anyway. the one 16v 2200uf cap was completely open as well as two 25v 47uf were also completely open. I replaced the three 35v 1000 uf as they were very swollen. The good news is the TV works great now. turns on every time and has a beautiful picture. thanks so much for your help.

[Shinju]

Re: Magnavox 37MF337B/37

Awesome work!

[budm]

Re: Magnavox 37MF337B/37

Glad to hear that you fixed it, thanks for the follow-up.

[Junkrepair]

Re: Magnavox 37MF337B/37

See my thread "Choosing diodes for Magnavox 37MF337B/37 power supply repair" https://www.badcaps.net/forum/showth...365#post749365

My case was very similar to the OP of the present thread. Mfr. date is the same (October 2007). Four large capacitors were bulged, and there were burn marks around the same diodes, although the burning on my board was not as severe. I replaced 11 caps and 6 diodes. Probably 2 or 3 of the diodes I replaced didn't need replacement. But it works now. I put together list of the parts I replaced, including old and new part numbers and specs.