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.

G'day,

There are quite a few harness connectors on these
beasts, and though they are mighty tight (just try to
get one off and keep the pins straight!) I wonder if
corrosion could be enough of an issue that one should
just pull them all, buff them somehow, and put them
back? At least in your case the one)s) to the audio
board!

Good luck!
the manicmaestro


--- jbfromoz <JB@...> wrote:
> 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.
> 
> 


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