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Conboy
Joined: May 01, 2009 Posts: 25 Location: London
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Posted: Wed Jan 30, 2013 12:35 pm Post subject:
Melted VCO! Subject description: destroyed VCO - repair advice? |
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I accidentally put a large voltage through my Yusynth VCO and burnt it out. The 2 resistors on the power input burnt out. I replaced them but it no longer works at all.
I'm not very good at trouble shooting ;-(
I have replace most of the IC's with no luck. There is power to all the chips on board - I can test that much!
Is it likely I will have destroyed the transistors too?
if anyone can offer any tips I'd be most grateful
thanks |
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minisystem
Joined: Nov 16, 2012 Posts: 35 Location: Toronto
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Posted: Wed Jan 30, 2013 2:48 pm Post subject:
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I shorted 120V AC through my first VCO and blew up my power supply in the process. When I next applied +/-15V the two input resistors went up in smoke, suggesting the high voltage zap had shorted something somewhere?
I gave up and built a new one rather than troubleshoot. |
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brock
Joined: May 26, 2011 Posts: 112 Location: Canada
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Posted: Wed Jan 30, 2013 9:56 pm Post subject:
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You don't say what the voltage was so it's difficult to answer definitively but if you had more than 36V or +/- 18V then you will want to replace all the ICs because even if they are still working they will die an early death. Transistors can be destroyed with high voltage too but the typical bjt will handle 50V or more Vce, Vbe is considerably less. If the voltage exceeded the voltage rating on the caps you might want to replace them too.
I would just assume all the ICs are damaged and replace them all.
If the voltage rating of any cap was exceeded, replace it.
If that doesn't fix things, replace the transistors. |
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LFLab
Joined: Dec 17, 2009 Posts: 497 Location: Rosmalen, Netherlands
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Posted: Thu Jan 31, 2013 1:47 am Post subject:
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+1
Would start with IC's and transistors, and then caps (electrolytic and tantalum, the other stuff is usually ok).
Desolder the lot, get new stuff in, use toothpick to clear holes of solder (heat with iron, touch with toothpick, there you go!). |
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yusynth
Joined: Nov 24, 2005 Posts: 1314 Location: France
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Posted: Sat Feb 02, 2013 11:01 am Post subject:
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Chances are that all the ICs are burned. _________________ Yves |
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Conboy
Joined: May 01, 2009 Posts: 25 Location: London
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Posted: Mon Feb 04, 2013 4:23 am Post subject:
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Thanks Yves
I have swapped all IC's with a known working VCO one by one and still no luck.
Power to all IC's seems fine.
replaced the J112 transistor.
Not a sound - very frustrating!
diodes and caps's next I suppose
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yusynth
Joined: Nov 24, 2005 Posts: 1314 Location: France
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Posted: Mon Feb 04, 2013 1:47 pm Post subject:
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Yes I think so... _________________ Yves |
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