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...
c.teaman
Member
Last Activity: 07-19-2014, 10:45 PM
Joined: 02-10-2013
Location: Harrisburg, PA
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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 continuesLeave a comment:
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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?Leave a comment:
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Re: Basic (I think) cap questions...
My apologies, I just realized that I started this thread under the FAQs section. I don't see an option to delete my own thread, so I guess I'll just leave it here for a mod to delete or move.Leave a comment:
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Basic (I think) cap questions...
I'm completely new to this, and have what i think are two basic questions...
First Question: When replacing a cap with an imperfect match, which is more important? Farads or volts? I have been assuming farads, but wanted to make sure I wasn't jumping to conclusions.
For example, if I am pulling a 2200uF/25v cap, would I be ok replacing it with a 2200uF/35v cap? or a 10v cap?
Second Question: How do you determine which caps are the startup caps?
I apologize if these are already answered somewhere else, I browsed for a bit and didn't see any obvious... -
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 replacedLeave a comment:
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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
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Re: MAGNAVOX no picture powers LED 47MF437B/37
Ok, I'm stuck... I'm just going to run through real quick what I've done... hopefully someone knows something I'm not finding.
All electrolytic caps replaced. All of them.
Fuse continuity test. Good to go
Replaced ZD902 and ZD904.
D912 0.001, 0.001 in circuit; but test normal outside circuit.
D926 0.365, 1.755 and climbing in circuit, normal outside circuit.
D928 0.355, 1.755 and climbing in circuit, normal outside circuit.
No progress. When plugged in, the red light comes on....Last edited by c.teaman; 02-13-2013, 11:47 PM.Leave a comment:
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Re: MAGNAVOX no picture powers LED 47MF437B/37
D912 tested fine when it was out of the board... .560, 1.0
I also noticed that Scatman was getting the same exact readings on D912 and it ended being resolved for him when he replaced zd902 & zd904. They were both completely destroyed... mine are functional.Leave a comment:
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Re: MAGNAVOX no picture powers LED 47MF437B/37
D912 0.001, 0.001
D926 0.365, 1.755 and climbing
D928 0.355, 1.755 and climbing
the last two are located right by the three 1500 uF capsLeave a comment:
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Re: MAGNAVOX no picture powers LED 47MF437B/37
So, I have now replaced every cap on the board... it still chirps and won't power on. The only thing that seems to indicate a problem is the three diodes that show bad numbers in the circuit. All three test fine out of the board. Any ideas? And am I damaging the caps I have just put in when I test it?Leave a comment:
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Re: MAGNAVOX no picture powers LED 47MF437B/37
I'm sorry to keep asking questions... is it acceptable to replace a 6.8 uF/50V cap with a 6.8uF/35V? I'm removing the capXon and replacing it with a rubyconLeave a comment:
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Re: MAGNAVOX no picture powers LED 47MF437B/37
Thanks so much, I really appreciate itLeave a comment:
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Re: MAGNAVOX no picture powers LED 47MF437B/37
Thank you very much, I'll replace that and see what happens. Would anybody be able to pinpoint it's location for me? I would upload a picture of my own, but my camera isn't nice enough. Would it be possible to show where it is on one the pictures already on this thread?Leave a comment:
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Re: MAGNAVOX no picture powers LED 47MF437B/37
I have spares for some of them, would it do any good to just throw them in?Leave a comment:
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Re: MAGNAVOX no picture powers LED 47MF437B/37
between 450-550 on each, infite (1) backwards...Leave a comment:
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Re: MAGNAVOX no picture powers LED 47MF437B/37
Thanks for the reply. Where should I look next to repair my tv? After replacing all of the caps, it still wont power up and I still get the chirping. The ZD diodes referred to earlier in this thread all test fine...Leave a comment:
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Re: MAGNAVOX no picture powers LED 47MF437B/37
I would really appreciate it if someone could give me some feedback... several of the diodes on my board are reading as bad in the board, but test fine once I remove them. What would cause this?Leave a comment:
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Re: MAGNAVOX no picture powers LED 47MF437B/37
and thanks to all of you who have already posted your help on this thread... reading through the past 5 pages has been extremely helpful. I tested the ZD diodes and they appear to be working properly... about .559 one way, 1 the other.Leave a comment:
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Re: MAGNAVOX no picture powers LED 47MF437B/37
Hey everybody, I can see this thread hasn't been active for several months, but I figured I'd check here anyway. I have the same model, 47MF437B, operating with the same problems. No power and chirping. I purchased it from someone who didn't want to try to fix it. It appears someone has already replaced the caps in an attempt to make it run. However, caps C951, C952, and C953 appear to have been replaced with 1500uF/35v caps. It looks like the caps in the pictures earlier on this thread are 2200uF, not 1500uF. I was wondering if someone...Leave a comment:
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