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Hi
I'm the original owner of my Poly800 mk1. It was my first synth! It's in pretty good
physical shape overall, but unfortunately it has seen better days. There seem to be some
very knowledgable people in this usergroup, so here is my situation.
Short; it's not making any sound, when it occasionally does make some noise on it's own
it's distorted as if the presets are corrupt and the sound does not always reflect any input
played on the local keyboard, and the MIDI has stopped outputting data.
My Poly800 worked great for many years. It saw some outdoor use when I was in
highschool marching band; once when we traveled to Canada to perform, I forgot my
keytar strap, so we ended up duct taping the keyboard to my band uniform. When we
marched, it rained, and the Poly800 did get a bit wet but not too bad. It worked fine for
many years after that.
I also had some alkaline batteries in it that I forgot about and they leaked, but the leakage
does not seem to have traveled outside the battery compartment. Inside the keyboard was
a bit dusty but there is no visible corrosion (a common problem in Hawaii, where the
keyboard (and myself) had been living the past years). I cleaned out the insides with some
compressed air but that hasn't solved my problem.
I'm not sure what exactly is wrong as they keyboard appears to be functioning OK (powers
up, can hear the headphone jack amplifier power up (just the click of it being powered up,
no excess noise), and when I attempt to flash it using a .WAV file of the original casette
data it says 'GOOD'.
However, the keyboard does not trigger the sound. Usually there is no sound, but
sometimes there is some spurious random output, like the DCO or VCF or something is
getting a corrupt/random 'preset' and the VCA is not usually responding to keyboard
input. It will sometimes audibly respond to the keyboard input, but the sound will be
accompanied by the noise generator going crazy or some random DCO output. Then the
sound will all stop and cut out suddenly. It usually won't make any more noise or respond
to the keyboard at all again, until I put it away and try again some other time.
The sequencer does advance per each note, and on the occasional output that does
respond the keybed/DCO's will seem to track accurately, so I don't think it's a problem
with the keybed itself.
I was just using it as a MIDI controller until that stopped sending any data, which lead to
my discovery of the audio problem. :(
I've tried flashing it a number of times, with all the write switches enabled (and in various
permutations; e.g. just program data). I've used a couple different .WAV files. The unit
claims to get a 'GOOD' flash. I had some trouble flashing it when I was trying to check up
on the MIDI and battery situation a while ago due to a bad cable, and then the audio
problems started up. So I don't know if they are related or if that is possible. It almost
seems like the OS (or ROM or CPU) are corrupt and it can't properly load/play the presets.
I haven't tried sending the data over MIDI sysex but again the MIDI out is buggered...
It seems unlikely the ROM is corrupt, but is there any easy way to test the ROM or CPU? Is
it possible to get these parts anymore without cannibalizing another Poly800? Do these
seem likely candidates or should I be investigating some other areas first? I have a simple
multimeter but not an oscilliscope. ..
Sorry to ramble but I've tried to be complete with the information related to the problem.
Please let me know if there are any questions or suggestions. And thank you very much
for your time.
Sincerely,
willi
http://www.earth2wi lli.com
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