[sdiy] P.S. troubleshooting help

[Scott]

Yeah, that's the exact same thing mine is doing.  +.66 volts on the negative rail.
I've swapped the big pass transistors as well as the regulator IC.  My negative supply has two more transistors, and everything else is passive.  I doubt a diode has gone out.  I think it has got to be the drive transistors.  

I'm getting ready to order replacement parts, but I wont know if it solves my problem for probably a week.


-----Original Message-----
From: synth-diy-bounces at dropmix.xs4all.nl [mailto:synth-diy-bounces at dropmix.xs4all.nl] On Behalf Of Finlay Shakespeare
Sent: Saturday, April 04, 2009 12:09 PM
To: synth-diy at dropmix.xs4all.nl
Subject: Re: [sdiy] P.S. troubleshooting help

Hi guys,

Just chiming in here to say I've got exactly the same problem. My Power One 
supply is used and has always worked in my possession until now... turned it 
on a few hours ago and the negative side was below 1V (not sure if this was 
due to DMM fluctuation/the - side is actually totally dead, or the true 
voltage was around -600mV). Again, the positive rail is working as usual.

I've tried with and without loads and the negative rail is exactly the same 
in both circumstances. Does anyone have any definite answer to what this 
could be (I haven't been fiddling with my supply at all recently) or is it a 
matter of going through a checklist? Nothing seems to have blown (i.e. caps 
or similar), all supply fuses are fine.

Cheers,
Finlay Shakespeare
www.futuresoundsystems.co.nr


--------------------------------------------------
From: "Cary Roberts" <cary.roberts at retrosynth.net>
Sent: Friday, April 03, 2009 6:32 AM
To: <synth-diy at dropmix.xs4all.nl>
Subject: Re: [sdiy] P.S. troubleshooting help

>>Can someone help me troubleshoot my power one hcc-15-3-A? I took it
>>out of my synth cabinet last night to test it. It tested fine.
>
> Sure you didn't short out the cases of the 2N3055s to each other or ground
> while messing around with the supply?  They're live and if they're shorted
> bad things can happen.
>
> Is the AC side of your supply fused?  If so what's the rating and type of
> fuse?  It shouldn't be more than a 2A fuse.
>
> Does your multimeter have a diode checker?  If so test both the pass
> transistors and the drive transistors.  If they test good swap in a new 
> 723.
>
>
> -Cary
>
> _______________________________________________
> Synth-diy mailing list
> Synth-diy at dropmix.xs4all.nl
> http://dropmix.xs4all.nl/mailman/listinfo/synth-diy
> 
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