Korg PolySix - Irratic Behaviour

Pulling out your hair? Don't know what to do or where to go? Ask in here.
Forum rules
READ: VSE Board-Wide Rules and Guidelines

If your Help request has been solved, please edit your first post in order to select the Image Topic Icon to let others know your topic has been solved.
Post Reply
justinvm
Junior Member
Junior Member
Posts: 209
Joined: Sat Jul 07, 2007 12:03 pm

Korg PolySix - Irratic Behaviour

Post by justinvm » Sat Feb 07, 2009 4:05 am

Hello,

I recently acquired a Korg Polysix off a friend for a very good price. They're somewhat rare in Australia so I jumped on the chance to buy it.

However the unit is not working.

Symptoms: Irratic flashing LEDs, Adjusting any of the paramters causes patch changes and seems to manipulate the sound in unpredictable ways. For instance the Cut Off potentiometer may cause the effects, lfo settings and eg settings to change simultaneously. None of this happens in a predictable way. So any adjustment of the front panel causes the entire sound to change.

(The voice allocation and appegiator buttons seem to be unaffected)

I was already aware of the Battery Leakage problem before I bought it. Infact, before turning the unit on I sussed out the patch cpu board for any such problems. It turns out that the original owner had done some repair work to it and replaced the battery.

I've since checked and repaired a few broken traces. But there has been no significant improvement what so ever. I can't seem to find any more damaged traces so I'm wondering if one of the logic chips needs replacement.

Does anyone have any idea what logic ics could be causing this sort of problem?

Cheers,

- Justin.

User avatar
SickMonkey
Newbie
Newbie
Posts: 96
Joined: Mon Feb 25, 2008 8:51 pm

Re: Korg PolySix - Irratic Behaviour

Post by SickMonkey » Sat Feb 07, 2009 8:58 am

I have one with the same problem. All swiches and buttons (except the arp/chord ones) are totally crazy. The pots seem to work as they should, though.

Mine actually worked before i messed it up somehow. I replaced the battery, and checked that everything worked, put it away for a while and when i brought it back out it was f**k. Some of the cables between the CPU board and the front panel were not properly connected, that's the only problem i could find.

sam
Expert Member
Expert Member
Posts: 1304
Joined: Wed Jun 21, 2006 10:09 pm
Location: Europe

Re: Korg PolySix - Irratic Behaviour

Post by sam » Sat Feb 07, 2009 9:45 am

You have to replace the chip above the battery, It's not easy and you will have to cut it out.

Google old crow battery repair for photo's...
Roland Vp330 mk1.SH101.juno 6.OSCar.ARP odyssey..Tonus 2600..omni.
ms20/50. OBX.
Prophet 5
Wasp.EMS AKS.

justinvm
Junior Member
Junior Member
Posts: 209
Joined: Sat Jul 07, 2007 12:03 pm

Re: Korg PolySix - Irratic Behaviour

Post by justinvm » Sat Feb 07, 2009 11:17 am

Sam what makes you think that would be the problem? Have you seen it before?

It looks as though the chip has already been replaced (edit: confirmed IC30 not original).

SickMonkey is yours still broken?

User avatar
SickMonkey
Newbie
Newbie
Posts: 96
Joined: Mon Feb 25, 2008 8:51 pm

Re: Korg PolySix - Irratic Behaviour

Post by SickMonkey » Sat Feb 07, 2009 12:19 pm

justinvm wrote: SickMonkey is yours still broken?
Yup. A shame really, because cosmetically it's basically new-looking.

sam
Expert Member
Expert Member
Posts: 1304
Joined: Wed Jun 21, 2006 10:09 pm
Location: Europe

Re: Korg PolySix - Irratic Behaviour

Post by sam » Sat Feb 07, 2009 2:57 pm

I have fixed 8 polysixes...And i always replace that chip.

I feel that chip has been replaced but the board has not been cleaned properly and some traces need fixing.

You have to make sure all the tracking is in order on the pcb.

Take your time and it will work again.
Roland Vp330 mk1.SH101.juno 6.OSCar.ARP odyssey..Tonus 2600..omni.
ms20/50. OBX.
Prophet 5
Wasp.EMS AKS.

sam
Expert Member
Expert Member
Posts: 1304
Joined: Wed Jun 21, 2006 10:09 pm
Location: Europe

Re: Korg PolySix - Irratic Behaviour

Post by sam » Sat Feb 07, 2009 4:05 pm

I have to add that i see a lot of bad soldering by 'have a go' techs that don't have the basic equipment and technique to undergo such tasks....

You can destroy the tracking if this care isn't taken...To much heat can damage the chip.

I feel that the problem lies there.
Roland Vp330 mk1.SH101.juno 6.OSCar.ARP odyssey..Tonus 2600..omni.
ms20/50. OBX.
Prophet 5
Wasp.EMS AKS.

Europe Endless
Newbie
Newbie
Posts: 14
Joined: Thu Jul 05, 2007 8:20 pm
Gear: Minimoog model D, Prophet 5 3.3, MultiTrak, Juno-60, 3xPolysix, Trident MkI & MkII, DW8000, DX7IIFD, KX88, and DIY Digisound SSM-based mono.
Location: Way north

Re: Korg PolySix - Irratic Behaviour

Post by Europe Endless » Sat Feb 07, 2009 9:45 pm

Have to agree with Sam. The only way to get it back to working order is to pull out the schematic and measure EVERY trace from the processor to IC30 and 31 and outwards. Painstaking, I know, but it´s the only way.
I haven´t gotten as far as repairing 8 Polysixes yet (just 6 :) ) and ALL of them have required PCB traces to be fixed around IC30 and 31. I usually use a thin wire on the solder side of the board to repair the traces, not trying to "retrace" the original trace with solder, which I´ve seen attempts to do. Also, I always cut away IC30 and 31, desolder the remaining pins and mount new IC in high quality sockets.

Also, watch out for defective CMOS chips 4051 (IC18, 19 and more) They are prone to fail sooner or later.

justinvm
Junior Member
Junior Member
Posts: 209
Joined: Sat Jul 07, 2007 12:03 pm

Re: Korg PolySix - Irratic Behaviour

Post by justinvm » Tue Feb 10, 2009 7:45 am

Thanks for the replies guys. You have motivated me to replace those chips and get this bad boy working again.

- Justin

User avatar
Synthaholic
Expert Member
Expert Member
Posts: 1206
Joined: Tue Aug 21, 2007 5:43 pm
Gear: Motif XS6, TX802, D-550, A6
Location: NH

Re: Korg PolySix - Irratic Behaviour

Post by Synthaholic » Tue Feb 10, 2009 2:28 pm

I've never owned/played with a "vector" synth, but I always wondered if vector synthesis entailed more than just mixing 4 parts with a joystick. Considering that the D-50 had a joystick which could be used to mix the 4 partials, but it was never considered a vector synth.

But, if it's just mixing/crossfading 4 parts with a joystick, many synths (romplers in particular) can do the same sort of thing, usually with sliders instead of a joystick.
Two VCO: thanks to the push rods, one can choose several forms of waves at the same time!
(from a Babelfish translation of a Jupiter-6 site)

Yamaha: Motif XS6, TX802 Roland: D-550 Alesis: A6 Andromeda

User avatar
OriginalJambo
Synth Explorer
Synth Explorer
Posts: 2560
Joined: Sun Jul 09, 2006 12:04 am
Gear: Check my sig
Location: Scotland, United Kingdom

Re: Korg PolySix - Irratic Behaviour

Post by OriginalJambo » Tue Feb 10, 2009 3:59 pm

Synthaholic wrote:I've never owned/played with a "vector" synth, but I always wondered if vector synthesis entailed more than just mixing 4 parts with a joystick. Considering that the D-50 had a joystick which could be used to mix the 4 partials, but it was never considered a vector synth.

But, if it's just mixing/crossfading 4 parts with a joystick, many synths (romplers in particular) can do the same sort of thing, usually with sliders instead of a joystick.
Wrong thread? ;)

User avatar
Electroluver
Supporting Member!
Supporting Member!
Posts: 265
Joined: Sun Dec 28, 2008 4:54 pm
Gear: MS-20, M-500, Polysix, PAiA 4700, ROL309, C64 MSSIAH, JX8P, K2000J, SY-1010.
Band: DJ NAMELESS
Location: Vancouver, Canada
Contact:

Re: Korg PolySix - Irratic Behaviour

Post by Electroluver » Wed Feb 18, 2009 12:32 pm

Can the leakage from the battery effect the sub osc switch? Mine`s not working at the moment. Neither is the memory. Thankfully the found button works , so I can work from the knobs.
Another thing; when I press a program button, it comes up with some weird sounds, not good sounds mind you. So, I think the sub osc might be in a few of these sounds, so I`m trying to work off them. I really just need to get it fixed eh?

justinvm
Junior Member
Junior Member
Posts: 209
Joined: Sat Jul 07, 2007 12:03 pm

Re: Korg PolySix - Irratic Behaviour

Post by justinvm » Tue Mar 31, 2009 3:07 pm

So I finally got around to replacing IC30 and IC31. Replacing these did not help at all.
Once again i gave the board another once over for damaged traces. The board is clean. I couldn't find any.

Any suggestions?

User avatar
rhino
Supporting Member!
Supporting Member!
Posts: 2611
Joined: Sat Aug 02, 2008 5:00 pm
Real name: bill
Gear: keepers:
Kurzweil K2500x
Ensoniq TS-12
Yamaha SY-99
Alesis QS-8
Roland JD-800
Roland JX-10
Akai AX-80
Ensoniq SQ-80
Korg DSS-1
Moog Mini
Fizmo
Location: kentucky hills

Re: Korg PolySix - Irratic Behaviour

Post by rhino » Tue Mar 31, 2009 3:28 pm

another guess.
if turning knobs and switches changes other parameters, check the pot/switch boards (2) for cracks, cold solder,BAD grounds etc.
When the wise man points to the stars, the fool looks at the finger.
- Confucius

justinvm
Junior Member
Junior Member
Posts: 209
Joined: Sat Jul 07, 2007 12:03 pm

Re: Korg PolySix - Irratic Behaviour

Post by justinvm » Tue Mar 31, 2009 3:34 pm

Bad grounds was my first guess. I haven't finished sussing those boards out yet. But everything looks squeeky clean so far.

Cheers.

Post Reply