I have Magnavox 37mf437d/37 and when I turn it on I hear a chirping. The green power light is on but the screen is black. I looked at the power supply and there are three capacitors that look like they are a little bulging. Could the bulging capacitors cause the tv not to work?
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Re: Magnavox 37mf437d/37 chirp
chirping can be a sign of a bad start-up capacitor,(33-50 uf 50v),or a sign of short,check voltages on psu,and check them to GND also,you want to see a high resistance in K OR MEG OHM,the ground pins will give you a reading of 1.5ohm.the startup caps will be in the primary section,check all your caps in the secondary esr and capacitance.
also check secondary diodes,these can cause a chirp if one or more have shorted.
and yes bulging caps can cause this issue,replace with panasonic fr/fm or fc series,fr being the best,fm second,and fc third choiceLast edited by multimeter; 01-07-2015, 04:38 AM.fixed so far...376 lg lcd tv's,24 onn tv;s,24 panasonic lcd,16 jvc lcd,12 marshall jcm800 amps,refurb of various disco equipment lighting,old style disco decks ,and a flymo!
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please let us know if everything works ok if your tv gets fixed, as it will be and aid for anyone else having the same problem and wishing to fix it.it would save people clogging up this site with topics that are duplicated,and can be found easily using the search function.,and taking up valuable space.enjoy your fixed tv!,hopefully! -
Re: Magnavox 37mf437d/37 chirp
I have checked all the diodes and they all show current going through them but I am just not sure if they are the correct voltage.Comment
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Re: Magnavox 37mf437d/37 chirp
If you have the chirping noise, you will most likely need to replace the 3 capacitors as well as diodes ZD902, ZD904, ZD906, and ZD908. I've repaired at least a dozen of these and my experience has been if it simply won't power up but has the standby light, it's just the capacitors. If it advances to the chirping phase, then the diodes have also failed.Comment
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Re: Magnavox 37mf437d/37 chirp
I have a couple of 1N4007 diodes laying around. Could I use those to replace the bad diodes?Comment
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Re: Magnavox 37mf437d/37 chirp
depends where in the circuit the diodes are,you need to check the part number written on them,you will find they may be UF4007 ETC ETC,which are ultra fast recovery diodes.
unsolder one leg of each diode and set meter to diode test,normal readings in diodes are reading one way when reversing probes,shottky diodes will have readings both ways but not shorted readings.fixed so far...376 lg lcd tv's,24 onn tv;s,24 panasonic lcd,16 jvc lcd,12 marshall jcm800 amps,refurb of various disco equipment lighting,old style disco decks ,and a flymo!
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please let us know if everything works ok if your tv gets fixed, as it will be and aid for anyone else having the same problem and wishing to fix it.it would save people clogging up this site with topics that are duplicated,and can be found easily using the search function.,and taking up valuable space.enjoy your fixed tv!,hopefully!Comment
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Re: Magnavox 37mf437d/37 chirp
also we could do with some good pics of the PSU to show you what,where,and how to test,without it its like the blind leading the blind.also a pic of mainboard could be helpfull.fixed so far...376 lg lcd tv's,24 onn tv;s,24 panasonic lcd,16 jvc lcd,12 marshall jcm800 amps,refurb of various disco equipment lighting,old style disco decks ,and a flymo!
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please let us know if everything works ok if your tv gets fixed, as it will be and aid for anyone else having the same problem and wishing to fix it.it would save people clogging up this site with topics that are duplicated,and can be found easily using the search function.,and taking up valuable space.enjoy your fixed tv!,hopefully!Comment
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Re: Magnavox 37mf437d/37 chirp
ZD902 and ZD904 -- P6KE120ACT-ND TVS DIODE 102VWM 165VC AXIAL
ZD906 -- P4KE250A-E3/54GICT-ND TVS DIODE 214VWM 344VC AXIAL
ZD908 -- 568-7930-1-ND DIODE ZENER 18V 400MW ALF2
Got all those at digikeyComment
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Re: Magnavox 37mf437d/37 chirp
If you change those 4 diodes along with the bad caps, you will almost certainly have a working board again. You can try the caps first but I doubt you'll have any luck without the diodes. My experience has been that once the chirping develops, you need to change the diodes too.Comment
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Hi is any one can help me on getting the Schematics for Magnavox MDR515H/F7 And Magnavox MDR537H/F7 PDF file thank you I really appreciate it. Just need to change some component on
the main board and the power supply board. I looked all over for the internet and I cannot find the Schematics sheet for both of them. I don't know where else to look I hope someone can help me...03-07-2025, 01:03 PM -
Dear Badcaps forum members,
Hope that you are all well!
I am a newbie on a mission to figure out the cause of the PSU making a "chirping" noise:
Having searched for this symptom online I have found some indication that failed capacitors may be an issue. To help with the troubleshooting, I have tried to isolate the problem and disconnected the PSU from the rest of the device - the chirping remained.
I have then found that the whole PSU (apart from a small add-on board) can be replaced, and there is even a datasheet for it: https://cdn.badc... -
Fixed a 10yo HP inkjet with a bulging cap on the digital computer power rails (1 to 5V). Unstable voltages causing these inkjets to not boot properly or crash quickly. Seems like more and more of these are showing up nearing the 10 year mark. Board design seem to look similar for many of these printers.
https://h30434.www3.hp.com/t5/Printi...t/true#M99792202-03-2025, 09:50 PM -
Would you consider a slightly bulging capacitor defective if it measures perfectly and it is brand-new? To be honest, they are all equally like this: vent is not totally flat but they have very low E.S.R. and VLOSS is negligible.
So, everything seems perfect apart from the vent looking a bit "strange". They are genuine capacitors, BTW.
The bad thing is that they are 400V capacitors so testing them just to check how much they last would mean using them on the primary of a power supply, which means the risk of damaging the whole circuit.
What do you... -
I have been using a Denon AVR-X2000 receiver in my living room for several years now, works perfectly, am very pleased with it. Recently I acquired another one, advertised as defective with flashing red led a few seconds after switching on. Picked it up to try repair and use in hobby room. After switching on, the on/off indicator led indeed initially flashes green for about 2 seconds, during which the display is visible, and then starts flashing red (at 2Hz) with a switched off display.
I'm afraid the service manual is too large to upload here (55Mb), it can be found at https:/...
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