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Subject: Re: Poly 800 MK 1 Short circuit

From: "kjelle.vergauwe" <bobsrampenbedrijf@...>
Date: 2012-07-29

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
> >
>