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
>