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Hello All
I have a Dual Stereo Buffalo DAC (two DACS in one box)
The first one I built in the box works perfectly and never had any fault.
The second one i built identical to the first has a placid BP power supply. Today when I turned it on the rectifier and/or Capacitor blew up (smoke and the burning electronics smell). Those are the only parts that seem to smell.
Now, this happened before and I replaced both rectifiers and its worked perfectly ever since until today. Can anyone just confirm what parts I should replace this time around? Both rectifiers and capacitors? Its a real hassle to replace the rectifiers .
In measuring S2A and S2B are DEFINITELY shorted, S1A and S1B are not.
Can anyone also maybe give any idea what might cause this to happen? Note I am running oversized transformers.. but just note I have another identical placid running with an identical transformer and config tht has never had any problems.
Cheers
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I suspect the fault is elsewhere on the Placid BP. Posting a picture of the board, transformer wiring, and enclosure mounting will be helpful in diagnosing the issue.
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Rank: Member
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Joined: 4/28/2013(UTC) Posts: 55 Location: Auckland Thanks: 1 times
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I have posted image below, don't show much. One thing that DID happen when I was building it was I inserted one of the transistors around the wrong way, and didnt properly set the variable pots and fired it up. It all got very, very hot, so i turned it off immediately, realizing i hadnt set the pots (it was late at night and i was under pressure to finish it). I re-examined the board and turned the transistor around the right way, set the pots correctly, and it all seemed to be fine. then the rectifier went shortly after that and I replaced it. Its worked fine for a few months since then and now that same rectifier has gone again. So thats the history... what do you recommend I do - make a new board? Replace the transistors, Caps and rectifiers? Are there some simple tests I can do. Currently the rectifier appears to be shorted (S2A and S2B) are shorted, other side seems fine. Cool, look forward to recommended action - i use this at gigs so I want the safest option to ensure it continues to work without a hitch. :-) Here are the images:    
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Rank: Member
Groups: Member
Joined: 4/28/2013(UTC) Posts: 55 Location: Auckland Thanks: 1 times
Was thanked: 1 time(s) in 1 post(s)
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Update here
So, I replaced the rectifier, and ran every test I could think of and both sides seem to work in the same way.
I have now re-installed into the box and run it up, works perfectly. Voltages are correct at 15v and shunt current of 50ma. Running DAC now and all sounds fine.
the only OTHER factor I can think of is each time I have had this fault its been when someone else has been using the DAC (and I am not there). I then collect it after the gig, get it home, turn it on and it pops.
Maybe the way whoever else is turning it off, maybe some kind of surge? Maybe when it is turned off along with all the other equipment (power amps) something weird happens?
Anyway, any tips of tests I can do to the power supply while its running I am happy to perform.
Thanks again!
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