The Magnavox 42mf337b LCD repair thread - Page 3 - Home Theater Forum and Systems - HomeTheaterShack.com
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post #21 of 28 Old 11-15-11, 03:45 PM
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Re: The Magnavox 42mf337b LCD repair thread

I didn't think it was the problem either. I replaced all 4 of those caps. I'm going to check caps in other boards to see if any are visibly bad.
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post #22 of 28 Old 11-15-11, 03:53 PM Thread Starter
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Re: The Magnavox 42mf337b LCD repair thread

I would'nt worry about the rest of the TV just yet. I did'nt have any problems with any thing else, besides the power supply.
The power supply was full of problems for me, capXon cap's, failed MOSFET, failed diodes and a noisy transformer.

Keep on trouble shooting the PSU.
Remove it from the TV, flip it upside down on your work bench, plug in the AC cord and put your volt meter on the single cap that's by it's self. You should see 12 volts. If not, check the large high voltage cap, you should see 200+ DC volts there. If you dont see the high voltage, then you have a problem with the bridge rectifier or the fuse (or other traces) are blown.

Use common sence when doing this. Dont let the board short out on any thing, and dont touch any thing.
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post #23 of 28 Old 11-15-11, 04:00 PM
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Re: The Magnavox 42mf337b LCD repair thread

I don't have much experience troubleshooting, and those step by step instructions are exactly what I need.
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post #24 of 28 Old 11-15-11, 04:06 PM Thread Starter
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Re: The Magnavox 42mf337b LCD repair thread

You might see more then 12v at that cap, I think there is a voltage regulator after that, that will bring it to 12 volts. So dont be surpriesed if you see 15volts or so.
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post #25 of 28 Old 01-14-12, 09:53 PM
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Re: The Magnavox 42mf337b LCD repair thread

I hate to bump an old thread but I was just wondering if anyone was ever to find a solution to this problem. I'm having the same "chirp" issue. I'm an electronics novice. I can test some components with a meter and solder but that about it. I ordered a "repair kit" for the board off ebay it came with replacement caps for C953 C952 C951 and C955. It also had 2 replacement diodes for ZD902 and ZD904. I replaced all the components but i still have the chirp and no picture.
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post #26 of 28 Old 01-15-12, 10:02 AM Thread Starter
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Re: The Magnavox 42mf337b LCD repair thread

Quote:
colonelget wrote: View Post
I hate to bump an old thread but I was just wondering if anyone was ever to find a solution to this problem. I'm having the same "chirp" issue. I'm an electronics novice. I can test some components with a meter and solder but that about it. I ordered a "repair kit" for the board off ebay it came with replacement caps for C953 C952 C951 and C955. It also had 2 replacement diodes for ZD902 and ZD904. I replaced all the components but i still have the chirp and no picture.
Yes I did find a solution to this problem. After swapping half the parts on the 24v side of the power supply, and it was still chirping and squeeling, I gutted it. I installed a meanwell 350 watt 24v power supply and tied it into the 24v side. I left the 12v section alone.
It still works great to this day. No more noise.

But, you need to do some test to see why your not getting a picture. Is your power supply making 12 & 24v? You need to have the power supply pluged into the TV and turn it on to get the 24v side to turn on.
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Last edited by jeffescortlx; 01-15-12 at 10:11 AM.
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post #27 of 28 Old 01-16-12, 11:05 AM
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Re: The Magnavox 42mf337b LCD repair thread

Just of the record, Home Theater Shack does not recommend users add external power supplies to a unit in this manner. There are many potential problems that one could encounter and many safety issues involved. We do not restrict users sharing experience, but we cannot make recommendations that have a high probablility of creating safety and functional hazards.




Looking for me, just google my username. I have used the same one for most sites for many years.
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post #28 of 28 Old 09-26-12, 05:42 AM
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Thumbs up Re: The Magnavox 42mf337b LCD repair thread

MASSIVE BUMP

THIS IS FANTASTIC!

There are dozens of forums with the fault of "whining" philips/magnavox pfl... power supply, none with a fix. This is awesome, and I hope somehow people will link to from these other sites, and I will probably do that also.

I did this exact same (very similar) fix for a power supply in a lift system! years ago, even removed the burnt out transformer, diodes pre-stage components and installed an external power supply. But I never even once thought of doing it to fix my TV. (I will probably be preforming this surgery with 2x 12v car batteries tomorrow! haha)

Please, can you write a detailed explanation, in a final summary post, describing the steps taken, what was removed and what was installed. (Is it possible to use a smaller power supply?) This will help many people on many forums, with many dead magnavox/philips TV's.

Thanks mate you've just re/opened my eyes.

TAGS: 715T2432-2 715T2432-3 ADPF24300R1P philips magnavox 42PFL7422 whining buzzing power supply TPT1.2a la

Last edited by Spannerz; 09-26-12 at 05:47 AM. Reason: Extra info
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