Unless you can see real physical damage to the coil, I doubt that the
coil would be the problem. Coils are generally very reliable unless
they are physically damaged by a direct impact, a sharp instrument
damages the windings or corrosion from battery or water.
I'm not certain of the voltages but I would check the capacitors first
- especially electrolytic's. Of all of the electronic components, they
age the fastest.
Mike.
--- In korgpolyex@yahoogroups.com, "Jon" <shonokij@...> wrote:
>
> Hi!
>
> I just got myself another broken Poly-800. (The first one I got is
now beyond repair. As I was
> offered a second one. I thought: Two minus makes a plus..). But now,
after picking the new
> one appart. It seems like the -5V circuit is broken. I've replaced
Q18. But the only reading i
> get is +0.9V where it should be -5V.
>
> Could it be that small transformer that's busted? (KD-4? xD-4? It's
hard to read the name on
> the schematics. And it says T1 on the circuitboard). The output of
it is +0.45V (Measured at
> leg 1 of D10), I asume it shoudl be -2.50V instead?
>
> Any ideas on how to replace it?
>
> The long way, I guess, is to replace the entire circuit with a AC-DC
converter that takes 9VAC
> in and with a 7805 and a 7905 regulates it.. But it seems like to
much trouble right now.. Or?
>
> Thanks!
>
> //Jon
>