Korg Poly800/EX800 Users

On Wed, 27 Jul 2011 19:04:26 -0000
"Bill Meirelles" <billmeirelles@...> wrote:

> Hi folks,
>
> It started yesterday, randon vcf positions as if it has an S&H LFO at the CV input of the VCF, I double checked the wiring and tried to disconnect all the pcb connectors and reconnect them several times, tried to move the wiring while the synth is playing to, I just can't find it. My guess is I should start looking for a broken solder and if I can't find any I should recap the filter circuit, am I right?

Only if you plan to scrap it afterwards.

Never, ever "recap" equipment.

If you find in the course of your investigations that some capacitors have failed, by all means replace them - and if you find that two of the six voices have the same capacitor faulty you may as well do the other four - but do not just go randomly ripping components out and changing them. That's a great way to ruin your gear.

Have you any reason to suspect the capacitors are in any way faulty?

Gordon MM0YEQ

On Wed, 27 Jul 2011 19:04:26 -0000
"Bill Meirelles" <billmeirelles@...> wrote:

> Hi folks,
>
> It started yesterday, randon vcf positions as if it has an S&H LFO at the CV input of the VCF, I double checked the wiring and tried to disconnect all the pcb connectors and reconnect them several times, tried to move the wiring while the synth is playing to, I just can't find it. My guess is I should start looking for a broken solder and if I can't find any I should recap the filter circuit, am I right?

Only if you plan to scrap it afterwards.

Never, ever "recap" equipment.

If you find in the course of your investigations that some capacitors have failed, by all means replace them - and if you find that two of the six voices have the same capacitor faulty you may as well do the other four - but do not just go randomly ripping components out and changing them. That's a great way to ruin your gear.

Have you any reason to suspect the capacitors are in any way faulty?

Gordon MM0YEQ

Is it actually drifting or rather switching abruptly?

I had a similar problem yesterday and it was one of the contacts of the 12dB/24dB switch which was coming loose. Re-soldering it fixed the issue.

Is it actually drifting or rather switching abruptly?

I had a similar problem yesterday and it was one of the contacts of the 12dB/24dB switch which was coming loose. Re-soldering it fixed the issue.

Is it actually drifting or rather switching abruptly?

I had a similar problem yesterday and it was one of the contacts of the 12dB/24dB switch which was coming loose. Re-soldering it fixed the issue.

On Wed, 27 Jul 2011 16:56:25 -0300
billmeirelles@... wrote:

>
>
> Now I can here it's happenig when in 12dB too, looks more like the voltage is
> changing just like a rando LFO will do but it comes a go, you never know when.
> Can be a bad cap, a broken solder or? Any ideas?

Stop guessing and start testing. Begin at the VCF CV input and work back. Check to see that if you hold a key with the VCF EG amount set to minimum that it actually holds a steady voltage.

The joysticks seem to lose their dead zone and go noisy. This makes the pitch bend, VCF mod and VCO mod go apeshit.

--
Gordon JC Pearce MM0YEQ <gordonjcp@...>

On Wed, 27 Jul 2011 16:56:25 -0300
billmeirelles@... wrote:

>
>
> Now I can here it's happenig when in 12dB too, looks more like the voltage is
> changing just like a rando LFO will do but it comes a go, you never know when.
> Can be a bad cap, a broken solder or? Any ideas?

Stop guessing and start testing. Begin at the VCF CV input and work back. Check to see that if you hold a key with the VCF EG amount set to minimum that it actually holds a steady voltage.

The joysticks seem to lose their dead zone and go noisy. This makes the pitch bend, VCF mod and VCO mod go apeshit.

--
Gordon JC Pearce MM0YEQ <gordonjcp@...>

Have you checked/disabled the FM-800 to see if that gave anything?