Can 1N4937 replace 1N4007 in switching power supply?

[tpd]

Hello,

Can I replace 1N4007 with 1N4937 in switching power supply (there are 4 of them playing gretz, burnt to the ground by short circuit)?

Thanks

[Kleinstein]

The  1N4937  has only 600 V rating. This can be a bit low when used with more than 200 V mains. In a normal bridge rectifier the diodes would see up to 2 x the peak voltage or about 2.8 times the RMS voltage - so 644 V for 230 V main and excursions to higher mains come on top.

The peak current rating also seems to be a bit lower and the forward voltage drop a bit higher, which may be an issue.

[tpd]

The  1N4937  has only 600 V rating. This can be a bit low when used with more than 200 V mains. In a normal bridge rectifier the diodes would see up to 2 x the peak voltage or about 2.8 times the RMS voltage - so 644 V for 230 V main and excursions to higher mains come on top.

The peak current rating also seems to be a bit lower and the forward voltage drop a bit higher, which may be an issue.

Thanks

[tunk]

Post photos of the PCB (both sides), then someone may be able to see if it's ok.

[MarkT]

Hello,

Can I replace 1N4007 with 1N4937 in switching power supply (there are 4 of them playing gretz, burnt to the ground by short circuit)?

Thanks

Given the 1N4007 is a slow rectifier it must simply be the bridge rectifier input, which doesn't see high speed switching - its best not to replace slow recitifers with fast ones as this can lead to much EMI generation.  Soft-recovery fast rectifiers are more suitable, but I'd replace 1N4007's with 1N4007's its not like they are hard to source.

You might want to investigate whether anything else is burnt out, 4 recitifers don't just fail for no reason - it might be a gross mains surge, but it might be over-current from the succeeding circuitry being shorted out.