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Subject: Re: [korgpolyex] Poly 800 problems

From: Michael Hawkins <korgpolyex800@...>
Date: 2008-11-25

No, I feel special !

Yes, I remember opening up my first early Poly-800 and seeing all the sleeved jumper wires and thinking - what is that?

So I think you might be OK there.

But your filter chip is another story. You can't have an NJM2069 missing pins.

Bottom left from the notch would most likely be the ground pin (pin 11).

Now the interesting thing is that there are two ground pins on the NJM2069.

So I am not certain that you actually HAVE to have both.

Someone needs to take their filter chip out and measure the ohm's between pin 1 and pin 11. If the multimeter shows a short then it's possible that you can do without pin 11. If it shows an open then you're going to have to get your dremmel out.

Is anyone near their Poly right now with a multimeter handy?

Mike.
From: Tyrone Lumley <tyrone_topheavy@...>
To: korgpolyex@yahoogroups.com
Sent: Tuesday, November 25, 2008 11:53:45 AM
Subject: Re: [korgpolyex] Poly 800 problems, IC

Wow, the Man himself responds !!!! I feel special ;)
 
Yes, solid core wire with clear sleeving, which means factory ? Good !
 
I already did the battery mod, it was easy. She remebers her patches now. But yeah, it seems to be an eraly model with no internal battery. SN is 009958.
 
The pin that has no leg anymore is the last one on the bottom left hand side, if the key is oriented towards the top (away from you). I don't have a data sheet so I can't tell you what number it is.

--- On Tue, 11/25/08, Michael Hawkins <korgpolyex800@ yahoo.com> wrote:
From: Michael Hawkins <korgpolyex800@ yahoo.com>
Subject: Re: [korgpolyex] Poly 800 problems, IC
To: korgpolyex@yahoogro ups.com
Date: Tuesday, November 25, 2008, 5:10 AM

Ty,

We should assess the situation before making any attempts at repair of it.

Since the board is without the battery it is most likely an early version of Poly. What is the serial number on the case?

In early versions Korg themselves fitted quite a few jumpers to the main board.

Are the jumpers that you see clear plastic with a solid silver core? If they are, they're probably Korg installed.

And before you go doing anything to the filter chip, which pins are damaged?

Mike

From: tyrone_topheavy <tyrone_topheavy@ yahoo.com>
To: korgpolyex@yahoogro ups.com
Sent: Monday, November 24, 2008 6:04:29 PM
Subject: [korgpolyex] Poly 800 problems, IC

Hey all.

I just rec'd a Poly 800 from "that auction place". In the past, I've
relaced the battery and uploaded the new sounds from my PC through
the tape jack, and I assumed this would be the problem with this one.

First, this is an early model, so no battery.

Second, I looked at the IC NJM2069D3004, and noticed it appeared to
be installed backwards, as it's "key" (the indentaion on the chip)
was opposite of all the other ICs on the board. So, I pulled it, and
observed some of the legs were missing or bent. Someones obviously
been here before me.

Also, I noticed several jumpers on the board that seem to be mods or
repairs. IC 24 has two of it's pins jumpered (20 to 23) IC 22 has
been jumpered to IC 24, and two capicitors are also jumpered (C95 to
C97).Lastly, the wiring harness that connects the main PCB to the
smaller brown one under the front panel appears to have had some
modification to it. Pins 1,2,3 and 4 on CN6A seem to have been
spliced.

I know the guy that makes the Hawk kits hangs out here, and you guys
know more about this synth than anyone. Do these mods look farmiliar
to you ? Can you tell me what someone was trying to do ? Is it
reversable ? Can I just break the jumpers ?

Also, since the pins on the IC are bent/missingm are there
replacements avaialable ? I've read elsewhere the EPROM can be
burned, and the data is on the net, but I have neither the equipment,
expertise not patience to burn my on ICs.

Or, is this a candidate for the trash pile ? I could always part it
out, I guess...

Thanks in advance for your help. This is a neat little grouop you
have going here.