Korg Poly800/EX800 Users

check at the joystock for the +/- 9V and the +/-5V
id be thinking its your power input stage to the whole poly

especially if you are not getting the LED display up

best regards,

JB

On 25/02/2007, at 1:38 AM, dharmaone1977 wrote:

> I've checked it with the multimeter now and the pin 9 and 8 on the
> 80C85 show 5v DC.. it doesn't respond to setting any parameters or
> the keys, just stays at this noisy sound after the initial
> filter/frequency sweep
>
> any ideas?
>
> Thanks!
> jouni
>
> --- In korgpolyex@yahoogroups.com, Michael Hawkins
> <korgpolyex800@...> wrote:
> >
> > If you have an oscilloscope or multimeter then download the
> schematics from our group web site and then check the test points
> that are shown on the schematic.
> >
> > If you have an oscilloscope then you can check the waveforms
> precisely. If you only have a multimeter then looking for some
> voltage will do.
> >
> > Disclaimer: Just be very careful poking around because you don't
> want to short anything out and do more damage than you already might
> have.
> >
> > Regardless of the condition of the display chips, the display won't
> show anything at all if the RES6.5 clock is not running. So check for
> voltage on pin 9 of the 80C85. It should read a little above 0 volts.
> >
> > Let us know what you find.
> >
> > Mike.
> >
> > dharmaone1977 <dharmaone1977@...>
> wrote: 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@yahoogroups.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!!"
> > >
> >
> >
> >
> >
> >
> >
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>
>