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Subject: Re: [korgpolyex] Re: Question regarding backup battery mod.

From: Marcus Wilson <JB@...>
Date: 2008-03-02

the headphone output that died on my poly was on the chorus board,

there is a 8 pin SIL chip amp that is the headphone amp

I managed to replace it with an 8 pin DIL amp using some funky wiring to make it work

try swapping the chorus board over to isolate the headphone amp issue on one board, and if it is definately there, I can locate the part number for the part i used to replace mine and bring it back to life

best regards,

Marcus Wilson

On 03/03/2008, at 4:57 AM, Funky Monkey wrote:

Holly crap, you must be looking over my shoulder.
 
I have 2 poly 800s
 
Poly 1 would not run on wall DC power (only batteries) and did not output at the headphone amp and had a backup battery installed but R1 and D1 was not cut. (good keyboard action though)
 
Poly 2 runs on batteries and wall DC and has headphone output (no Li-Ion installed).  But had a kina warped keybed with uneven note triggering (a later job).
 
So i just now i took the good Top (Poly 1) and put it on the Good Bottom (poly 2).  Now it runs on batteries and Wall DC but still no Headphone Out.  So Im thinking that the headphone out is upperboard related.  Any help would be met with a song of praise.
 
 
 


 

To: korgpolyex@yahoogroups.com
From: JB@designlab.cx
Date: Mon, 3 Mar 2008 04:42:52 +0900
Subject: Re: [korgpolyex] Re: Question regarding backup battery mod.

Hi there!

when you mention the headphone amp gone bad, I had that issue with one of my polys, and I managed to jury rig a repair, that has worked well

do you still have the first poly? and are you interested in a how to to fix the headphone amp? (im assuming that the L/R 1/4" trs connectors still output line level fine)

best regards,

Marcus Wilson
On 02/03/2008, at 3:08 AM, funkymonkeypeter wrote:

This is my second Poly-800. The first had a problem with the
headphone amp and DC-in jack. This one works great and I don't want
to muck it up.

If some one can answer my question I promise not to tell anyone what
really happened on 9/11.

So, to cut or not to cut?

--- In korgpolyex@yahoogroups.com, "funkymonkeypeter"
<funkymonkey3.14@...> wrote:
>
> Regarding the instructions here:
>
> http://analog.no/mods/korg_poly-800_mk-1_battery_backup.htm
>
>
> ∗ Open the Poly-800 by removing all screws at the bottom. Locate
> the processor board. This is the large circuit board next to the
> battery compartment.
> ∗ In the upper left corner you'll find Resistor R1 and Diode D1.
> Remove these. (Just cut the legs, but leave as much as possible of the
> D1 legs, see next steps.)
> ∗ If you have a late revision MK-1 there will be two fairly large
> solder "islands" in the center of the board. The battery is mounted
> here. The "island" to the front of the keyboard is ground.
> ∗ If you have an early revision you wont find this. The battery
> must then be connected by wires, the plus to the junction between
> R1/D1 and the minus to the other leg of D1.
> ∗ Any 3V lithium with solder lugs can be used as long as it is not
> to big physically for mounting to the board. A wristwatch type (2025,
> 2032) is fine.
>
>
>
> I have the model with the solder islands, do i need to cut the legs to
> R1 and D1? Or can I just solder to the islands and leave everything
> else intact?
>
> Thank you.
>