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Subject: Re: [korgpolyex] poly 800 II fails

From: Michael Hawkins <korgpolyex800@...>
Date: 2011-08-08

"Have you checked for battery leakage inside? (Especially the C cells).
I have battery leakage, i have to remove the battery and the support"

Take photos of the boards (front and back) showing where the C cells leaked onto the boards.

The damage could be severe enough that your Poly is simply not able to be repaired.

How long was it between when you last used the Poly and it was working and when you next tried to use it and it didn't?

I ask because if the damage has only just occurred then you may be able to stop any further damage by carefully washing the affected boards. If the goop has been sitting there for some weeks or months then damage will probably be deep and very severe.

To clean the boards you will need a stiff brush (I used a toothbrush), strong soap (detergent - do NOT use bleach or other corrosive household chemicals). A sink large enough to submerge the boards. Warm water. A hair dryer and a really hot dry sunny day.

Also, you may need to wash the header cables too. Do you see battery goop on the cables or the connectors that the cables connect to? If you do then you need to very carefully remove the header cables and clean them too. If some of the pins are so badly corroded that the cables just break off or some of pins have completely disappeared then you are facing a very difficult restoration.

Remove the affected boards. Remove all cables. Remove the EPROM from the socket and set aside.

Submerge each board in warm soapy water and thoroughly scrub ONLY the affected areas. Once the affected areas are clean of acid goop - remove the board, thoroughly rinse in clean water. Then use a blow dryer to dry the board. DO NOT melt components or over heat them. Take plenty of time to dry the board. Once free of loose water, place in a hot dry sunny place. Leave for 24 hours to allow the remaining water to dry off. Do NOT rush the board back into service. Do NOT try to test the board out until you know it is thoroughly dry.

Repeat for each affected board. Do the same thing with the cables if they were affected too.

At this point, I think the damage is bad enough that even after doing the above cleaning you will have some significant work to do to revive your Poly.

Provide us with photos before cleaning and we can try to help. But I can tell you that I had one Poly that was C cell "gooped" and it is sitting in the spare parts bin. Very sad!

Mike




From: bruno lhuissier <bruno.lhuissier@...>
To: korgpolyex@yahoogroups.com
Sent: Monday, August 8, 2011 10:44 AM
Subject: Re: [korgpolyex] poly 800 II fails

 
Hello Mike

yES this is a Poly MK2 that I have had for many years?

Did it have this problem from the moment you bought it?

No it worked good until one day ,it don' t I open it and: I saw the C cell battery leakage





Have you checked for battery leakage inside? (Especially the C cells).
I have battery leakage, i have to remove the battery and the support

Did you check the power supply rails? Check them all when you first power up and then again after 2 minutes or more? Do they drift across those two minutes?
 
Not yet i am going to check all the power supplies

Do you hear white noise (or pink noise) as the swooshing sound at power up? Or do you hear nothing at all at power up and you have to hit keys and the VCF cutoff sounds like it is increasing for those two minutes? (Slowly widening the sound until you hear the full range of harmonics).

yes i exclatly 
hear nothing at all at power up and I have to hit keys and the VCF cutoff sounds like it is increasing for those two minutes? (Slowly widening the sound until you hear the full range of harmonics).



Did your Poly work just fine with the mod's in place? Or, did you do the mod and then the problem occurred? Did you do the modding yourself?
yes the poly work fine with my moog slayer mod , the cutofff and resonance are ok.
I did the modding myself, sir !!

Does the sequencer work? Have you uploaded the factory patches? Are you able to edit sounds?

yes, since I change my tempo pot which was dead
I upload the patches, all seems to be fine
I am able to edit them

Does the EG3 work?
No the eg3 don't work , neither the VCF . I change the value of cutoff and resonance on the led screen without hearing any change , neither the e.g. int , neither the polarity.Only my mod gives me control on the filter !




Do the EG's for the individual DCO's work?
The ADSR seems to be good , except I hear only a "gate EG" on or off but i haven't all the values between.