I've got exactly the same problem!!!
got my poly800 mkI 2nd hand, LED display/keys not working, the only
thing it gives is a slow sweep from sub bass to high freq noise a few
secs after turning it on, then stays making noise until i turn it off.
chorus, filters and oscillators hence work.
Any ideas?
When powered the IC's all seem to have a voltage across them apart
from the LED IC. could it be a broken IC or (hopefully) something in
the +-5V power circuit not giving the board proper juice? the voltage
regulators maybe?
It's not mkII so it doesn't have internal battery.
No signs of leaked caps or cold solder joints or physical damage...
Tested with both batteries and 9V adapter
THANKS!!
Jouni
--- In
korgpolyex@yahoogro ups.com, "Rob" <r.bowe@...> wrote:
>
> Well, the Poly-800 I saved from the dumpster is not looking too good
> at the moment! The bad news is that it has no LED read-out of any
> kind, no flashing, nada. The good thing is, is that as I checked the
> V+ at the input I caught it dropping a few volts and suspected some
> kind of life! I proceeded to connect a set of phones to it and lo and
> behold, the unit gave me a real slow, but sweet pitch, amplitude
> and filter sweep, in stereo several seconds after start-up! It all
> swept up to a max and held. The only thing I can do to the sound is
> tune it with the slider and turn it up and down with the volume pot.
> Absolutely nothing else works. (I can affect the res. and cut-off with
> VR's 2 & 3) So obviously the power, amp, filter and oscillator (not
> necessarily in that order!)sections are working fine. Is there a
> secret button combo or power-up trick that would re-initialize this
> thing or is the back-up and sysex "lost"? The lack of display is a
bother.
> As you may remember from my previous post, I am a fairly effective
> bench tech and a damn good solderer and I read schematics fine, so
> even if there is something wrong at the component level, I shouldn't
> have any problems doing the fix, as long as someone out there has seen
> this problem before and knows the situation here. Aside from some one
> familiar with this glitch, it will be a stretch. Hopefully it won't be
> a big deal, so if you have an idea, I'll try to raise another Korg
> back from the dead! Otherwise, I have a really huge mono-patch, single
> sweep noise machine.
> I am sure that's why I got this for nothing! But in the words of
> Monty Python...
> "IT"S NOT DEAD YET!!"
>