Korg Poly800/EX800 Users

I've heard from a tech that he's replaced Q1 transistor two times in a row on two different Poly800's with failed power.

Once he replaced it, the units powered up just fine.


You're very lucky it didnt do more damage.. needless to say, I bet you'll never use that + plug supply on it again.. or on any other device with input/output jacks nearby it.
Good lesson for me to remember.
Glad your Poly is still OK at the core... that was a close one.




--- In korgpolyex@yahoogroups.com, Martin Ator <cyllall@...> wrote:
>
> You need a new Q1
> 
> 
> 
> ________________________________
>  From: kjelle.vergauwe <bobsrampenbedrijf@...>
> To: korgpolyex@yahoogroups.com 
> Sent: Sunday, 29 July 2012, 13:12
> Subject: [korgpolyex] Re: Poly 800 MK 1 Short circuit
>  
> 
> Â  
> Yup it still works fine on batteries. I can live with that.
> What needs to happen to make it work again on a regular PSU?
> Does the Circuitboard need to be replaced? Or wil resoldering components do the trick?
> 
> --- In korgpolyex@yahoogroups.com, Gordon JC Pearce <gordon@> wrote:
> >
> > On 29/07/12 12:27, kjelle.vergauwe wrote:
> > > Ok I retried measuring C3 and C4. For some reason I was probably doing something wrong.
> > > C3 & C4 measure  around 580 and I get a 'beep' now.
> > 
> > No, don't measure the resistance, measure the voltage across them.  You 
> > reckon you saw 0V, so the circuit around Q1 isn't working.
> > 
> > This is most likely because shorting the supply killed Q1 - if you 
> > notice, it's between the negative terminal of the power lead and ground. 
> >   If you shorted the positive terminal of the PSU to ground, you'd dump 
> > all the current the PSU can provide into Q1 backwards, and it wouldn't 
> > enjoy that...
> > 
> > You'll probably find it'll work just fine on batteries.
> > 
> > -- 
> > Gordonjcp MM0YEQ
> >
>