Have you tried sending a SYSX dump of the original patches to the
Poly? I have found MANY a poly\ex that were sold at garage sales and
thrift stores because no-one could figure out why they didn't hear any
sound, or only heard noise and blips. After a Sysx dump, 8 times out
of 10 it'll fix the problem...
The poly's memory is battery backup, so there is decay after years of
no-use and makes the patches corrupt.
Erik
--- In
korgpolyex@yahoogroups.com, "selloutdesigns" <aah_public@...>
wrote:
>
> Stop me if you've heard this one before...Bought an "As Is" Poly on
> eBay. Cleaned it up, plugged it in a lo and behold no display. Sound
> is present at the headphone jack about 30 seconds after turning on.
> It's a frequency sweep from low to high (sounds almost like the whoosh
> of a jet engine starting) followed by constant white noise. This sound
> is affected by turning VR1, VR2 and VR3 trimpots.
>
> I'm okay at basic electronic troubleshooting and repair, but have run
> out of ideas, so wondering if anyone has had a similar experience. I
> have pretty much determined it is not a power supply circuit issue (as
> I was hoping when I bought it). All the IC's I sampled are getting
> correct power. Also on connector KLM596 CN6A, Pin 6 shows 4.98v, Pin 8
> shows -5.07v and Pin 9 shows 9.44v, all of which I believe to be
> normal and show the power section is working OK.
>
> Unfortunately, I do not have access to a scope. Is it even worth going
> any further at this point without one? In a previous post where
> someone had a similar issue, it was mentioned that if the RES6.5 clock
> was not running this could cause a dead display. I did check RES
> 5.5,6.5 and 7.5 pins on M80C85A chip. RES7.5 pin shows 1.45v, but the
> other two are 0v or at least < 1 mv.
>
> Any ideas or suggestions on where to look next?
>