DAC-12M070 AF Diode

[flocko]

Hi and thanks for looking can anyone help me find replacements for D 205/204 on this board please, the marking on the diodes are PJ949 JZ have been trying to find data for it but having no luck Flocko

[flocko]

Re: DAC-12M070 AF Diode

Forgot photo, have two boards this one shows PJ88 JZ still unable to find data

[R_J]

Re: DAC-12M070 AF Diode

Whats the transistor number beside the diode? might be able to find the equivalent circuit somewhere, its most likely a zener of some kind.

[budm]

Re: DAC-12M070 AF Diode

Can we see good clear focused pictures of the top and bottom sides of the board? Picture in post 2 is not in focus for to see what the function of those two diodes are for.

[flocko]

Re: DAC-12M070 AF Diode

Hi and thanks for the help, first the transistors are marked 9973GH and i think are N channel mosfets (AP9973GH) that show data drain-source =60V, Gate-source=+20V,Drain current= 9-14Amp,i have been given two of these boards to repair or make one good one. Both have been played with?As can be seen in photos the best one being the one with the mosfets removed the other has had fuses soldered over so best not go there,the two diodes on the board i want to repair are shorted, i removed the mosfet as they were showing shorted on the board but were both good off,as you will see these drive the inverter transformers,any help finding replacements for the diodes and also confirmation that i have the right mosfets Flocko

[R_J]

Re: DAC-12M070 AF Diode

The best I can come up with is SMF51A Protection (snubber) diode. I could be way off though.
It is used because the fet is driving an inductive load (transformer)

[momaka]

Re: DAC-12M070 AF Diode

For testing, you can try some regular 3A fast recovery diodes rated for at least 50V Vr. I think those should work fine. In fact, you can see from the top-side picture that there are markings for two axial diodes right below the inverter transformers. I guess in the final design, it was cheaper to use the SMD diodes over the axial diodes, so that's why they used those.

There also appears to be a 3A(?) pico-fuse on the solder side, just a little below and to the right of the left snubber diode. If that's the case, make sure to grab some spare fuses in case these blow out. Again, just for testing, you may use a regular fuse if you want by soldering some wires to it and moving it somewhere where it won't short anything out. This should allow you to test these boards with some inexpensive parts.

Let us know how it goes.