Discussion about the Korg PolySix synthesizer

I suspect the power supply.
You may want to check it with DVM and oscilloscope during the warm-up
phase. Or you just replace the electrolytics in the P/S without any
measuring. After decades they probably lost substantial capacity and
need replacement anyway.



On 2019-01-22, 00:46 cwc@dircon.co.uk [PolySix] wrote:
> 
> 
> After many weeks refurbishing my "new" old PolySix I am very nearly 
> there! I have one last issue before the final tune up and I wondered if 
> anyone had any ideas. All knobs, switches and buttons on the synth work 
> and do what they should. The KLM-367 board is a brand new clone with new 
> clone CPU so I assuming that it is ok.
> 
> 
> The issue is that when I turn the PolySix on from cold, the MG frequency 
> is properly set as designated by the preset but "leaks through" at a 
> higher level than the preset's actual values causing a significant 
> wobble in the tone. This happens even when changing presets. Turning the 
> MG frequency and MG level controls to 0 will not entirely eliminate 
> this. At the same time, the arpeggiator pulse leaks into the tone 
> causing "catches" in the tone that can be varied by turning the Arp 
> Speed control. However, all these issues gradually fade as the synth 
> warms up and after a minute or two and the synth works perfectly. On 
> switching the synth off and on again when warm there is a slight MG 
> wobble in the tone on pressing a key which disappears in seconds. Then 
> all is good.
> 
> 
> This suggests to me that a component(s) is faulty and is \u201cleaky\u201d but 
> starts to function correctly when it has warmed up. Any ideas?
> 
> 
> One other thing I would like to know is whether how long the synth 
> typically takes to initialise. I have noticed that when cold the buttons 
> light for around 8-10 seconds before the synth initialises to preset A1, 
> but when it is warm it initialises instantaneously.
> 
> 
> 
>