bosoz PSU help!?

hello everyone. im 99% done with my bosoz, but as i was putting it together for the last time, i blew the PSU boards :bawling:

i looked on the boards and it seems like the 1N4005's blew. the traces between some of them blew too :( its repairable, but i would like to figure it out before it gets hooked up again. i had this whole thing working before, so im confused as to what's happening. here are the boards im using:

im using a single transformer for both channels, and i have two PSU boards. here is the troubleshooting i have done:

1.) traced back wires, everything seems ok, see the diagram below

2.) unhooked psu boards and checked to see if voltages are right. both secondaries are giving 67vac

3.) boards were working fine at one time and nothing has changed since then, so i ASSUME all parts are in the right way, etc...

here is a diagram of how its wired. (currently i am just testing one board at a time, to get rid of extra variables.)

the transformer is a avel lindberg, primaries are grey/brown and violet/blue. secondaries are orange/yellow and black/red. these are the exact same wiring that my aleph3's are, and i just mirrored them. and like i said, its been working just hooked up directly on the bench, and without the psu boards hooked up, the voltage is right...

thanks guys. im almost done, and this thing will be STUNNING (south american bubinga front panel with 30+ hand coats of lacquer, recessed plexiglass inside faceplate for LED's, etc... its gorgeous)


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well, the first time i hooked it up, i turned on the power switch for a fraction of a second and heard a loud hum, and i turned it off before anything happened.

the second time, i had just one board hooked up. then i hooked up the OTHER board after rechecking the wiring, and it did the same thing.

hum, so after reading what you said, i dont think that would have mattered, because i only had one hooked up at a time.
Do not assume anything. I always double and triple check component location and orientation before connecting power and I always try to use a variac to bring the power up slowly so I don't blow up traces on the PC board. I also never connect the power supply in a project to the main circuit until I am sure the power supply is working on it's own. You don't want an untested power supply taking out your preamp board. It certainly sounds as if one of the diodes was misinstalled or as Pinkmouse suggested a dead short right after the bridge rectifier on the board. Is it possibile that you installed the 1N4005 diodes that go between the sources on the FETS and the junction of the 221 ohm and 4.7K are reversed or the IRF540 and IRF9540 swapped. Also check that the bridge rectifier diodes were orienteed correctly. Remember the banded ends of the diodes are the cathode. Thats all I can think of.
thanks guys.

i didnt really assume much...

i had all this hooked up before and it worked without a problem. and NOTHING has changed since then. so, im not sure whats going on. i will look back over things tonight when i get home from work.


ill have to try that, thanks.


i wish i had a variac, but i dont. and i DO NOT have the pre-amp hooked up at all, im just testing the power supply alone right now. i probably have the 1N4005's reversed or something... i have a bad history with diodes (i had a bad diode in my aleph3 and it took a month to figure it out!)


once i get the PSU working, ill take some preliminary pics. the back panel is all cardas premium input/output RCA's, and the whole thing is milled and inked and lettered by front panel express. it turned out nice.


2004-03-23 10:43 am
i had all this hooked up before and it worked without a problem. and NOTHING has changed since then. so, im not sure whats going on. i will look back over things tonight when i get home from work.
Component failure does happen, smells like that could be the case. I have had several diode faults, that resulted in quite a work, finding out:xeye: Just took a look at your homepage, are you running that BosoZ from a 800VA? Thats for sure overkill:D
I like your Aleph chassis;)

of course 800va is overkill :)

the idea behind it was that i couldnt find a readily available xformer in the voltage i needed in a smaller size. and i WAS planning on doing full dual mono (two xformers), but at the cost plitron and others wanted to charge for two, i could get the 800va for less money. so, i just went that route. plus, it adds a good amount of weight to the chassis making it feel more substantial.