47mf437B/37 replace the four caps and still have chirping and no power. which diodes

[jdkruse]

Magnavox 47mf437B/37 replace the four caps and still have chirping and no power. which diodes should i replace?

[ReeceyBurger123]

Re: 47mf437B/37 replace the four caps and still have chirping and no power. which dio

Have you even tested the diodes ?

[jdkruse]

Re: 47mf437B/37 replace the four caps and still have chirping and no power. which dio

I have tested a few of them in circuit. I was wandering if there was a common diode or group to look at first. the board is slightly brown near some of the diodes does this indicate definitely a burned diode or do they get that hot? this is my first attempt on a television although I have replaced caps on a few boards in washing machines.

[ReeceyBurger123]

Re: 47mf437B/37 replace the four caps and still have chirping and no power. which dio

Take them out of crcuit, sometimes they fail leaky rather than shorted only way to know is to pull them and test.

[jdkruse]

Re: 47mf437B/37 replace the four caps and still have chirping and no power. which dio

I will pull them. Is the discoloring of the board an indicator?

[ReeceyBurger123]

Re: 47mf437B/37 replace the four caps and still have chirping and no power. which dio

Yes, any diode with discoloration near it could be faulty. I had a Vestel 17PW26 with no standby but fuse etc was good, the Pfc diode had lots lf discoloration near it and was getting very hot, after removing found that it wasn't shorted but had a voltage drop both ways meaning it was bad. After replacing it set worked fine.

[jdkruse]

Re: 47mf437B/37 replace the four caps and still have chirping and no power. which dio

Thank you. how will I determine what size diode to purchase? they are black with just a silver line (cathode) mark.

[budm]

Re: 47mf437B/37 replace the four caps and still have chirping and no power. which dio

Pictures of your power supply board?
The ones that usually failed are ZD902, 904 (P6KE120A) due to leakage. Also check D925 also (these are the diodes for the 24V power supply section) the STBY 12V will be D924, ZD906.
I do not know if my diagram matches your board or not.

[jdkruse]

Re: 47mf437B/37 replace the four caps and still have chirping and no power. which dio

this it with new and old caps. only the 2200 was bulged but I put all four in.

[jdkruse]

Re: 47mf437B/37 replace the four caps and still have chirping and no power. which dio

those you mentioned have discoloring of the board under them as well as D924 & ZD906

[budm]

Re: 47mf437B/37 replace the four caps and still have chirping and no power. which dio

OK, I look the wrong section, it will be D924, ZD906 P4KE250A for the 12V STBY power supply..
The standby power supply for this board is 12VDC.
Lift up one leg to test them.

[jdkruse]

Re: 47mf437B/37 replace the four caps and still have chirping and no power. which dio

thank you. I will pull and test them when I go back to work. have better equipment there. I'm getting parts from Mouser Electronics. any better recommendations?

[jdkruse]

Re: 47mf437B/37 replace the four caps and still have chirping and no power. which dio

Thanks budm. Those diode numbers P4KE250A & P6KE120A, do they replace what I think is a standard diode and a zenor diode? or am I looking at that wrong?

[budm]

Re: 47mf437B/37 replace the four caps and still have chirping and no power. which dio

Those are the P/N of the TVS Diodes - Transient Voltage Suppressors P4KE series and P6KE series.

http://www.mouser.com/ProductDetail/...zrnBQKw77Y8%3d

http://www.mouser.com/ProductDetail/...BdEy4gqM13g%3d

[jdkruse]

Re: 47mf437B/37 replace the four caps and still have chirping and no power. which dio

parts are ordered.