Korg Poly800/EX800 Users

> >i just printed out the manual when one thing caught my attention:
> >the poly 800 i bought has *naturally* no adaptor included ,sigh...
> >but i have a 9v 500mA adaptor, will it work? or is it gonna fry the
> >synth, since the manual says thas 300mA ones should be used?
> you won't fry it with 500mA. As long as the voltage, polarity, and plug
> size are, and the current of the adapter is 300mA or more then it will work.
> a 500mA power supply will run cooler and last longer too. But if somehow
> the Poly 800 shorts out, you'll be frying it with more current.

On the topic of frying, in the article I found about installing a backup battery
(mine didn't have one, but had the solder pads, so must be the second edition
mkI), it said to cut one lead of D1 (ie. remove it without physically removing
it) - any thoughts on why this is so, and what the implications are? I did what
it said, but am not too happy about the thought of any loose current frying the
board...
IIRC, when I looked at my original fried poly, the service manual said that D1
was the main protection circuit - but of course there was no D1, so...??

As far as mod articles go - I'll have a go at compiling any that I find into a
single source sometime "soon" (which for me can define anything from one hour to
one year... )

Lee
http://www.baudalign.com

>On the topic of frying, in the article I found about installing a >backup
>battery (mine didn't have one, but had the solder pads, so must >be the
>second edition mkI), it said to cut one lead of D1 (ie. remove >it without
>physically removing it) - any thoughts on why this is so, >and what the
>implications are? I did what it said, but am not too >happy about the
>thought of any loose current frying the board...
>IIRC, when I looked at my original fried poly, the service manual said
> >that D1 was the main protection circuit - but of course there was no >D1,
>so...??

Not that I know anything about the internals of the Poly but I would guess
that removing D1 has something to do with transferring power to the RAM chip
from adapter power to backup battery power. Cutting one lead is a nice way
to disconnect it because it's easy and it's not too hard to reconnect it if
you want. If it's a protection circuit, I can imagine it being either one
of two things. First, it could protect against reverse voltages (either
installing batteries backwards or using the wrong adapter)....but then
disconnecting it to use the backup battery would keep it from turning on at
all and anyway it wouldn't have anything to do with the backup battery. Or
second it could be a zener diode designed in some way to protect against
overvoltage. Maybe the way it's set up the backup battery would short out
with it present. Interesting...

_________________________________________________________________
Get your FREE download of MSN Explorer at http://explorer.msn.com/intl.asp

> >IIRC, when I looked at my original fried poly, the service manual said
> > >that D1 was the main protection circuit - but of course there was no >D1,
> >so...??
>
> Not that I know anything about the internals of the Poly but I would guess
> that removing D1 has something to do with transferring power to the RAM chip
> from adapter power to backup battery power.

I went back and checked, and it turns out the protection diode is actually D2. Hmm,
think I might have a look in my current poly to see if D2 exists in this one...

I've uploaded a text descriptor of each circuit section of the schematics - it's a
graphics-to-text conversion of a scan I did of the text in the service manual (which
I no longer have), so there may be a couple of glitches in the conversion, but I
think most of it was right, and I manually fixed any bits the converter couldn't
read.
A hell of a lot smaller to download (also a lot easier to read) than the original
jpg of the text... if only we could do that with circuits, too!

PS. Olaf, I like the idea of the panel-mounted sequencer and program write switches
- saves having to fumble around the back trying to figure out which switches are
which! Could also wire up some LEDs that come on when write is enabled... ooh, blue
ones, now that would be cool...! ; )
PPS. Your wiring efforts are a hell of a lot neater than mine. ; p

> PS. Olaf, I like the idea of the panel-mounted sequencer and

program write switches

> - saves having to fumble around the back trying to figure out which

switches are

> which! Could also wire up some LEDs that come on when write is

enabled... ooh, blue

> ones, now that would be cool...! ; )
> PPS. Your wiring efforts are a hell of a lot neater than mine. ;

p


Thanks (2 times).
Nice idea with the additional LEDs. But I'd prefer red ones, it's
more vintage-synth-alike, red means "warning - memory changes!" and
it fits to the red display LEDs.
But, I think surfers also like neon yellow, pink, and so on, so it's
ok if you choose blue ones ..... 8-)

Olaf

Could you please tell me the value of D2 for the poly 800 , I fried
the diode using the wrong adaptor. The schematics arent much help , I
cant read the value . I think it says S R 1K but I could be wrong .
The synth still works with the batteries . Unforttunatly it refuses
to accept patch loading , something to do with the blown diode I
think. Anyway thanks in advance.

It's not critical part, you can use any rectifier diode you find,
from 1N400x family (1N4001,1N4004...), but _do not_ use small
signal diodes like 1N4148. It's in there to protect the circuit
from wrong _polarity_ (not voltage) by coducting. You obviously
applied wrong polarity. It should have survived (that's why
you should use stronger diode).

> Could you please tell me the value of D2 for the poly 800 , I fried
> the diode using the wrong adaptor. The schematics arent much help , I
> cant read the value . I think it says S R 1K but I could be wrong .
> The synth still works with the batteries . Unforttunatly it refuses
> to accept patch loading , something to do with the blown diode I
> think. Anyway thanks in advance.

--



marjan


me : Marjan Urekar
e-mail: urekar.m@...
s-diy : http://surf.to/marjansystems
music : http://go.to/forcemajeure

Thanks for the info and the patchsheets:)Although I figured out D2
for my self 10 mins after posting I used a 1n4000.I know all there is
to know about diodes now:).I still can't get it to work. No power
from the adaptor and the headphone jack doesnt work either. It still
works fine with batteries;. Any suggestions?.
Damn wish I could find my multtimeter.

--- In korgpolyex@y..., ">>>marjan<<<" <urekar.m@e...> wrote:
>
> It's not critical part, you can use any rectifier diode you find,
> from 1N400x family (1N4001,1N4004...), but _do not_ use small
> signal diodes like 1N4148. It's in there to protect the circuit
> from wrong _polarity_ (not voltage) by coducting. You obviously
> applied wrong polarity. It should have survived (that's why
> you should use stronger diode).
>
> > Could you please tell me the value of D2 for the poly 800 , I
fried
> > the diode using the wrong adaptor. The schematics arent much
help , I
> > cant read the value . I think it says S R 1K but I could be
wrong .
> > The synth still works with the batteries . Unforttunatly it
refuses
> > to accept patch loading , something to do with the blown diode I
> > think. Anyway thanks in advance.
>
>
>
> --
>
>
>
> marjan
>
>
> me : Marjan Urekar
> e-mail: urekar.m@e...
> s-diy : http://surf.to/marjansystems
> music : http://go.to/forcemajeure

>Could you please tell me the value of D2 for the poly 800 , I fried
>the diode using the wrong adaptor. The schematics arent much help , I
>cant read the value . I think it says S R 1K but I could be wrong .
>The synth still works with the batteries . Unforttunatly it refuses
>to accept patch loading , something to do with the blown diode I
>think. Anyway thanks in advance.

do the schematics have a parts list? try checking that...


_________________________________________________________________
Get your FREE download of MSN Explorer at http://explorer.msn.com/intl.asp