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Smoking uP VCO 111-3

2019-04-15 by jbragg@fernforest.co.uk

Hi there,

accidentally plugged in power to a 111-3 the wrong way and smoke came off the poor little thing.

I would like to point out that the cable was wired back to the front and this time it wasn't my fault.

A friend with a multimeter says there is continuity now between -12v and ground which isn't good.

He can't work out which component is fried.

Any suggestions and help please.

Jamie B

Re: Smoking uP VCO 111-3

2019-04-16 by man.of.mystery@ntlworld.com

If your chips are in sockets, you could start by taking them out (note the orientation first) and checking if you still have the short.

I'd start with the electrolytic capacitors (can shaped) on the grounds that they don't like reverse voltage, and are cheap to replace.

Then I'd replace the TL084, for the same reason.

If the transistor shaped thing is a voltage regulator, you could see what the output voltage is, and maybe replace that - though I don't know what it's supposed to be.

The CEM chip can be replaced too, but not as cheaply. E.g:

https://electricdruid.net/product-category/oscillators/

- Andy

AW: [Doepfer_a100] Re: Smoking uP VCO 111-3

2019-04-16 by yahoo@doepfer.de

Fort he A-111-3 all circuits are in sockets. As recommended I'd replace at first the TL084. If this does not help the CEM3340 has to be replaced too.

The correct polarity of the bus connection cables is described in the FAQ page of our website:

www.doepfer.com > English > FAQ > A-100 > Orientation of bus connection cables

Best wishes
Dieter Doepfer

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> -----Ursprüngliche Nachricht-----
> Von: Doepfer_a100@yahoogroups.com [mailto:Doepfer_a100@yahoogroups.com]
> Gesendet: Dienstag, 16. April 2019 05:45
> An: Doepfer_a100@yahoogroups.com
> Betreff: [Doepfer_a100] Re: Smoking uP VCO 111-3
> 
> 
> 
> If your chips are in sockets, you could start by taking them out (note
> the orientation first) and checking if you still have the short.
> 
> I'd start with the electrolytic capacitors (can shaped) on the grounds
> that they don't like reverse voltage, and are cheap to replace.
> 
> Then I'd replace the TL084, for the same reason.
> 
> If the transistor shaped thing is a voltage regulator, you could see
> what the output voltage is, and maybe replace that - though I don't
> know what it's supposed to be.
> 
> The CEM chip can be replaced too, but not as cheaply.  E.g:
> 
> https://electricdruid.net/product-category/oscillators/
> 
> - Andy
> 
> 
>