Korg Poly800/EX800 Users

So check the power rails to the chorus board. There are three: +5, -5
and +9 volts.
Then check the chorus signal line. Which I think you're saying you
checked that. But I can quite tell from your message below if that is
what you actually tested.
You can also test the noise gate signal line too. Press a key and the
noise gate to should turn on, and wait until the EG's all finish, and
it turn off. Helpful to know if you're testing is actually working.
/MikeOn Thu, 2018-10-11 at 13:25 +0000, amorrison651@... [korgpolyex]
wrote:
> Hi Mike
> 
> 
> Thanks a lot for the reply. So I've checked with my multimeter and
> can't see any differences between on/off (1/0) settings on parameter
> 48. So I suppose this a power issue to the chorus board
> 
> Best Wishes,
> Andrew
> 
> 
> ---In korgpolyex@yahoogroups.com,  wrote :
> 
> Hi Andrew,
> 
> Best to start looking at the chorus control signal that goes from the
> main board to the chorus board. Use a multimeter to check that the
> signal goes up and down when you turn chorus on and off. You will
> need to download the schematics from the files section.
> 
> /Mike
> 
> 
> On Sunday, October 7, 2018, 2:32:55 AM EDT, Andrew Morrison
> amorrison651@... [korgpolyex] <korgpolyex@yahoogroups.com> wrote:
> 
> 
>  
> Hey All,
> Recently picked up a very grubby but very functional unmodified korg
> poly 800 mk1. Love the sound of the filter :O Everything seems to
> work (all the keys/midi/buttons/other parameters) as it should,
> except for the chorus which will just not turn on. I've tried it in
> stereo, mono and headphones separately.
> I've had a look under the hood and whilst it was quite dusty, I've
> cleaned that all out and can see no signs of battery acid
> leakage/damage and comparing to other online photos I can see no
> cosmetic damage. The top and underside of the chorus board looks
> perfectly intact and undamaged to my eyes.
> I've reset to factory settings and got fresh batteries in there but
> no luck getting that chorus to turn on. Anyone have any ideas on
> whether I'm missing something simple here, happy to provide some up
> close picks of the internals if anyone has any ideas?
>