Archive of the former Yahoo!Groups mailing list: Korg Poly800/EX800 Users

G'day all,

Just spent the last couple of days reading the archive so i could get
up to
speed on the history and archive of this list.

Sounds like some clued up people on the list :-)

I got my poly-800 at a swap meet for $10 in ∗dead∗ condition, and
have
managed to revive it with some replacement parts in the power supply
section, having found the schematics and manual online.

It now powers up with 11 p as default, will send midi control info
out to my
voce electric piano, so it appears the digital side is working
correctly now. I
have not got any sound out at this stage however.

At first i thought this was due to a dead tone generator chip, (MSM
5232) so i
was in the process of unsoldering this and socketing the chip while
trying to
find a replacement. however after reading the archive, i believe it
is possibly
just due to the lack of patches in memory.

So tonight i will re-solder the TG and try to reload the factory
patches from the
files section.

I am curious on the battery front, I believe mine is a mk1 poly, as
it has the
chorus board inside, it also has the solder pads for a backup
battery, however
doesnt look to have ever had a battery in place.

This makes me wonder how the device would have shipped originally
from
korg, would they have shipped with 6 c cells in it, to hold the patch
memory?
did it come with a tape copy of the presets? or what? if there is no
backup
battery on the board, it would seem likely that the patches would not
be held
in ram on original delivery.

very interested in any comments on this.

I have familiarised myself with the circuit to a point where i am
basically
confident with the various sections of the circuit, and having found
some more
info in the files section of this archive, have better info on which
part of the
schematic relates to which block of the synth.

some of the questions asked very early on about the magic black smoke
coming out with reverse polarity 9vdc input sounds possibly like the
input
stage polarity protection diode D2 may have melted down due to it
shorting
the supply in the case of reverse polarity. hopefully this will have
stopped
further damage to other components, and those dead synths could be
revived
using a replacement D2.

My board had died and was providing no -5vdc or +5vdc and i managed
to
ressurect it by replacing Q3, Q18 and Q1 with some current model
power
transistors. after doing this, she powered straight up, with supply
voltage +
and - and with led display all functioning, but no tone out.

Midi all works, storage of patch info appeared to work etc, however,
not
having hard copy of patches meant no quick ad dirty ∗try this∗ at the
time, and
it appeared that the issue was no tone out of the generator.

anyways, great to find this list, and hopefully catch up with some of
you further
down the track. Greetings to moose who i've run into a few times in
the past
on oz.org #macintosh irc group, still got your poly dude?

All the best, JBfromOZ

Marcus
Perth Western Australia.