Korg Poly800/EX800 Users group photo

Yahoo Groups archive

Korg Poly800/EX800 Users

Index last updated: 2026-04-05 20:10 UTC

Message

Re: Poly 800 MK 1 Short circuit

2012-07-29 by kjelle.vergauwe

What exactly do you mean with "You need to see if power is getting out now?"
I'm fairly lost at this. :)

--- In korgpolyex@yahoogroups.com, Martin Ator <cyllall@...> wrote:
>
> You just have an unregulated power supply. When it starts working the volts will drop down to about 10 or 11. It's high because your poly isn't using any power.
> 
> If you are measuring that voltage at Q1 then power is getting there.You need to see if power is getting out now?
> 
> 
> 
> ________________________________
>  From: kjelle.vergauwe <bobsrampenbedrijf@...>
> To: korgpolyex@yahoogroups.com 
> Sent: Sunday, 29 July 2012, 12:14
> Subject: [korgpolyex] Re: Poly 800 MK 1 Short circuit
>  
> 
> Â  
> 
> Between 12.88 and 13.14.
> 
> I suspect that it should read 9 :p Hmm. 
> 
> Weird.
> 
> --- In korgpolyex@yahoogroups.com, Martin Ator <cyllall@> wrote:
> >
> > If you measure your 9v power supply do you get 12.88v?
> > 
> > 
> > 
> > ________________________________
> >  From: kjelle.vergauwe <bobsrampenbedrijf@>
> > To: korgpolyex@yahoogroups.com 
> > Sent: Sunday, 29 July 2012, 12:03
> > Subject: [korgpolyex] Re: Poly 800 MK 1 Short circuit
> > 
> > 
> >   
> > I hope I did nothing wrong but here are my results...
> > 
> > C3 measures 0
> > C4 measures 0
> > 
> > middle leg of Q1 with the +leg of C4  measures 12.88
> > 
> > I set my multimeter to 20 V DC. PSU is 9V DC PSU, which still works with other equipment.
> > 
> > --- In korgpolyex@yahoogroups.com, Gordon JC Pearce <gordon@> wrote:
> > >
> > > On 29/07/12 10:32, kjelle.vergauwe wrote:
> > > > I'm not really good with a multimeter, but....
> > > > Just tested the Diode. I'm measuring 587 and 1. No beep though.
> > > 
> > > A "1" in the left-most digit of the display?  That means "infinite". 
> > > Those readings look pretty healthy.
> > > 
> > > > Also noticed when measuring that the wires from the diode are black, I could scrape black dust off of it. (see picture)
> > > >
> > > > http://dl.dropbox.com/u/7760238/poly%20800/Diode.JPG
> > > >
> > > 
> > > That's just the plating getting oxidised, it's normal.
> > > 
> > > Refer to page 1 in the diagrams I linked to in my previous post, bottom 
> > > left corner.
> > > 
> > > With the AC adaptor plugged in and the power switch on, measure the 
> > > voltage across C3 (little disc ceramic capacitor) or C4 (one of the 
> > > three electrolytics near there).  You should see about 9V.  If not, 
> > > measure the voltage between the positive side of C4 and the middle leg 
> > > of Q1 (2SB744).  You should see whatever voltage the PSU is putting out.
> > > 
> > > You may need to remove Q1 from the board to test it, but I bet that's 
> > > what the fault is.  If you're not comfortable with soldering and 
> > > desoldering, then find some friendly neighbourhood electronics geek to 
> > > help you ;-)
> > > 
> > > -- 
> > > Gordonjcp MM0YEQ
> > >
> >
>

Attachments

Move to quarantaine

This moves the raw source file on disk only. The archive index is not changed automatically, so you still need to run a manual refresh afterward.