MAGNAVOX no picture powers LED 47MF437B/37

[c.teaman]

Re: MAGNAVOX no picture powers LED 47MF437B/37

Dude, you are awesome. Thanks so much... I took a look at the SCH earlier but couldn't make heads or tails of it. I'm a ChE, not an EE I'll look into that then, thanks very much

[budm]

Re: MAGNAVOX no picture powers LED 47MF437B/37

On testing the two snubber zener diodes, test them using the highest ohm scale, report the reading in both directions. By the way, you are not getting 24v, right?
By the way the startup cap for the 24v is C921, 100UF 25V, has it been replaced?

[c.teaman]

Re: MAGNAVOX no picture powers LED 47MF437B/37

ZD904
Diode test on DMM: .538, 1
20M Ohm: 5.18, 5.31

ZD902
Diode test on DMM: .535, 1
20M Ohm: 4.95, 4.85

And yes, C921 has been replaced

[budm]

Re: MAGNAVOX no picture powers LED 47MF437B/37

OK, that is good, in the Mega Ohm range.

[c.teaman]

Re: MAGNAVOX no picture powers LED 47MF437B/37

Ok... Frustration is mounting. I replaced Q917, but still same issue. D926 and D928 still giving me the same readings, indicating a short. Anybody have any idea where else I should look?

[c.teaman]

Re: MAGNAVOX no picture powers LED 47MF437B/37

i do realize that my claim of "no power" earlier is not entirely accurate. The button does turn red, and upon pressing it, turn green. For a moment. After about 2 seconds, it turns red again and the chirping continues

[c.teaman]

Re: MAGNAVOX no picture powers LED 47MF437B/37

Should I consider scrapping the power supply and buying a new one at this point? I don't even know what to test next...

[netwzrd]

Re: MAGNAVOX no picture powers LED 47MF437B/37

I acquired (free) a 47MF437B that powers on but chirps. The screen is black but when I press the menu button I can see a very faint menu box and can make out the word picture. I am trying to decide if it is worth fixing or if I should give it to a repair shop. I have no experience with repairs but could manage a board replacement.

[Dgtech]

Re: MAGNAVOX no picture powers LED 47MF437B/37

Post pics of the screen and the boards. Too bad i dont still live in Middle River, down 40 from ya.

[netwzrd]

Re: MAGNAVOX no picture powers LED 47MF437B/37

Ok here are the pics of the boards. The 3 green caps are raised on top and the black one next to the red and black wire is raised as well. The screen is very dark but in one section I can see part of the menu when I press the menu button.

Like I said if I can get this fixed cheap great otherwise it is out the door. Doesnt even have a stand, remote or cable.

[Jtmcgarry]

Re: MAGNAVOX no picture powers LED 47MF437B/37

I have the same chirping issue with the power supply for this TV. I followed all of the suggestions in this thread. Although I think only the 2200 uf capacitor was bad, I replaced the 4 capacitors (one 2200 uf 16V (C955) , and three 1500 uf 35V (C951, C952, C953)) and 4 diodes (ZD904, ZD904, D926, D928) and I still have the chirping. Any ideas before I throw in the towel?

Thanks!
Jack

[Jtmcgarry]

Re: MAGNAVOX no picture powers LED 47MF437B/37

I have the same chirping issue with the power supply for this TV. I followed all of the suggestions in this thread. Although I think only the 2200 uf capacitor was bad, I replaced the 4 capacitors (one 2200 uf 16V (C955) , and three 1500 uf 35V (C951, C952, C953)) and 4 diodes (ZD904, ZD904, D926, D928) and I still have the chirping. Any ideas before I throw in the towel?

Thanks!
Jack

I just replaced C921 too. It was 100uf 25V. I put in a 100uf 35V. Still chirping...

[Rmasters3]

Re: MAGNAVOX no picture powers LED 47MF437B/37

Anyone got values or specs or manufacturer's part numbers for the D912 and Q917? I've replaced the caps and the ZD's under the transformer, but thought I might do the D912 and Q917 while it's apart.

[nautical naturist]

Re: MAGNAVOX no picture powers LED 47MF437B/37

Hi, NauticalNaturist here.
I also have a problem with a Magnavox 47mf437b37. I use a repair kit from LCDalternatives.com. This kit contained the most commonly damaged caps, diodes, and zeners. The kit made improvements, but did not cure the problem. Scott with LCD alternatives sent me more components on a "beta tester" basis. These made a further improvement, but did not cure the problem. Scott then directed me to this site for additional help. Anyone interested? The TV does not squeal or chirp now, but the picture flashes then goes black in a "2 flash/blank 2flash?blank" pattern. I now have less than $20 in parts and no problem with doing a little trouble shooting if necessary.
Thanks, NN

[cory1108]

Re: MAGNAVOX no picture powers LED 47MF437B/37

Can anyone help me trouble shoot a magnavox 46me313v/f7. I am very much a novice when it comes to tv repair but have fixed a couple for myself and friends. Original issue was when u plugged in the indicator light would flash continually so I suspected bad components on power board. I purchased a used power board and when installed the tv would then start up as soon as u plugged into power would stay on 10-15 seconds then power off and repeat until power was disconnected. The only way I could keep it from continually powering off and on was to disconnect the connector for the or sensor board. Any ideas as to what could cause this issue?

[K-man]

Re: MAGNAVOX no picture powers LED 47MF437B/37

Going to attempt to change some diodes. What kind/grade of soldier do I need to get?
Thank you

[K-man]

Re: MAGNAVOX no picture powers LED 47MF437B/37

Well I'll be!!!!!! Tv wouldn't turn on last week, had a chirping sound. Because of the info this site, I was able to repair it. Watching Red Wings now...... Changed 5 diodes ($2.00 + $5 for shipping). I believe the zener diodes 902 & 904 were the problem.

I SO HAPPY!

Thanks to all who posted info in this thread! I repaired my $1k TV for $7 bucks!

[ThePR0tector]

Re: MAGNAVOX no picture powers LED 47MF437B/37

This thread is a few years old and continues to help us newbs out. A few weeks ago someone gave me a Magnavox 42mf531d/37 that wouldn't turn on, in hopes of giving it to someone who could get some use out of it. I'd changed LCD monitor capacitors before and guessed that was the issue with it. Changed the caps and plugged it in to find it chirping from the Power supply board. Did more reading on it and hoped the issue would be fixed by changing the two diodes next to the Transformer. Wasn't even able to check them with a multimeter, just took them out and replaced them and presto! No more chirping! Works perfectly! Only wish Magnavox had made a better OSD for their TV's. Thanks BadCaps forum!