Jeantech JNP-500AP - Diode identification

[seanc]

This PSU was manufactured in 2004. I pulled this power supply out of a customers PC, plug it in, the 5vsb would come up and so would a high pitched whine.

Popped the lid and noticed a blown 100µf 25v cap and a 1000µf 16v. I've done a full re-cap on this, including the small caps (except three small ones near the primary side I can't get to).

I flipped it over to put it back together - (it has a PCB attached to a heatsink) and noticed a charcoal resistor.
I have another of these manufactured in 2006, but also upgraded to ATX V2.0.
I found the resistor colour of red, red, black, gold and replaced with one I had in a pack of resistors.

Powered it up but it still whined. Investigated the zener diode next to the resistor, it was cooked too. Since I couldn't read anything on the diode, I took it out of the working PSU. It says 27 on the top, 3 on the bottom.

I can measure:
Diode: 0.76
Resistence: 26-28 MΩ <- Not sure that's quite right...
Volts in circuit: 16v

The resistor and diode are next to a 10uf 50v cap.

So, how do I work out what zener to replace it with? I can provide pictures of either PSU if required.

[seanc]

Re: Jeantech JNP-500AP - Diode identification

Bump.

Can anyone share some wisdom?

[stj]

Re: Jeantech JNP-500AP - Diode identification

probably 27v

but you really need to relace those small caps - dont say you can get to them.
you mean without desoldering the heatsinks & transistors/diodes.

[ratdude747]

Re: Jeantech JNP-500AP - Diode identification

yeah, those small ones are critical and have ruined otherwise good supplies. there is some really low uf 50v cap that falls into the category.

[seanc]

Re: Jeantech JNP-500AP - Diode identification

I'll have to de-solder the heatsinks and all attached bits and bobs then. Probably a weekend job.