Korg POLY-61 suddenly quit working?

[wolfox]

Hey guys, need some help here...

I recently turned on my poly-61 and started playing for a bit, then all of a sudden the sound started distorting, not sounding right, getting quieter and finally just making faint popping sounds. Now all it does is make popping sounds sounds every time I hit a key. The display still lights up fine and parameters/patches change but no sound except for the tapping and popping. The battery has recently been changed and synth was working perfectly. The only thing I can think of is that I dropped the lid on the synth (while dusting inside) and it made a loud clank and then I noticed that the ground cable attached to the lid was severed, however, temporarily attaching the ground cable did not fix the issue. What do you think my next step should be in fixing this? Could it be a fuse even though the fuses look ok? Please someone point me in the right direction or tell me what you think might be the issue. I don't want to to spend a lot of $ on repairs, so I would rather try to tackle this myself somehow. Thanks

[wolfox]

Anyone? Any suggestions would really help.

[cornutt]

Usually this sort of thing is caused by a dead transistor in an output stage somewhere. I'm not very familiar with the Poly-61... does it have a headphone jack or any other alternate outputs you can check? That might be a start. But often, the failure will be in an output amplifier or something else that's pretty close, circuit-wise, to the output jacks.

[Jabberwalky]

With the synth open, when you play keys you should see an LED on each voice card light up. That would at least clear up that the cpu works. Can you edit the patches to get any change in the popping?

[wolfox]

Thanks for your responses. Yes, all voices light up and popping sounds do change as I change patches and edit. Headphones don't work either...same popping sounds. So what do you guys think?

[cornutt]

Thanks for your responses. Yes, all voices light up and popping sounds do change as I change patches and edit. Headphones don't work either...same popping sounds. So what do you guys think?

I still think it's an output amp circuit somewhere. It's unlikely to be anything with the voice circuitry, since you can't hear any of the voices. However, you might also want to check the power supply voltages. If, like a lot of synths of that era, it uses +5V for the digital logic and other voltages for the audio circuits, if one of those voltages goes off, the audio will quit working but the panel functions and all will still work.

[Jabberwalky]

+1

[wolfox]

Thanks guys, I'll start with checking the power section. BTW, Jabberwalky, I like your music, man. Good stuff.

[Jabberwalky]

Awesome, thanks wolfox. I use the Poly61 in my music a lot, and would hate to see one die.

[wolfox]

I wanted to give you guys an update. I put the p61 away for months, and when I turned it on just now everything worked perfectly for about 2 minutes and then the sound started distorting and fading out again and now it's back to just popping sounds when I hit keys. Display values change and buttons work, but that's about it. Does this help identify the problem? I checked the main power supply and it was at +5V, but I don't know enough about electronics to test anything else.

[Sophomore]

Hi
I have the exact same problem with mine..did you solve the issue?

[oryjen]

Allways begin by checking the memory battery.

[Sophomore]

I changed it only a couple of years ago when i put in a new battery holder for the safe kind of battery

[oryjen]

Well, then check all connectors inside. Very poor quality...