[sdiy] Prophet 5 power supply issues solved - fuse resistor frying now

[Gil W.]

Hi all,

You probably remember my DIY power supply issues,
well, they seem to be solved as soon as I got the
original P5 transformer (part number DP-241-8-36
available from Digi-Key), and changed the electrolyte
capacitors to tantalums, as on the original PS.

Just to remind, this P5 I got with no bottom/rear
panel and PS. The +15v filter cap on the main board
was an electrolyte instead of the stock tantalum, and
the fuse resistor was burnt out. 

I then decided to build the a PS, and had a few
problems, among them, a frying -15v tantalum capacitor
on the main board each time I powered it up, dropping
+15v voltage, some missing and bad ICs on the voice
board.

Well, I put all missing ICs on the voice boards,
replaced the bad ones, recapped all polarizes
capacitors with new tantalums, and replaced to broken 
pots.

After reaching this point, I no longer have any of the
above mentioned symptoms, but new were coming up:

1. I now get the +15v tantalum capacitor placed on the
main board, frying each time I power up.

2. When I replaced the cap with an electrolyte one the
fuse resistor blown up.

This brings me to the point where the previous owner
decided to ditch the instruments. The tech who
serviced it probably replaced the tant. with an
electrolyte, like I did now, and got a fried fuse
resistor.

One note - the cap doesn't fry when I connect the main
board to the PS, without being connected to the front
panel circuit. The above mention problem occurred when
I connect the main board and the front panel boards to
the PS, keeping the voice board unconnected (to
prevent from damage).

This brings me to think that the problem lays in the
front panel ??....

Any advice ?


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