Vintage Synth Repair

Hi guys,

I have a little problem with my Korg Delta.

It uses a top octave synth chip (TOS) to generate the notes for the divider chips. It is (or rather was) the AY-3-0214. This chip ran rather warm and then suddenly died on me a few weeks ago. I have sourced a "KS-196" retro fit board equivalent for this 'AY' chip and have installed it. It works, in as much as the synth now plays and I am getting all the keys working - but when I turn it on now, the tuning seems all over the place. The relative notes (up the keyboard) are fine on each transpose setting and it's playable but when I switch the transpose, it doesn't transpose by an octave. And the interval it switches seems to vary - almost like it's warming up. I seem to remember that before with the old chip it was playable and in tune right from switch-on. Also, the 'sound' seems noisey, not clean, like I am hearing noise along with the oscillator waveform. (The noise slider is off by the way)

Any tech's here have any idea what this could be? This retro board is (supposedly) a direct replacement for the 'AY' chip, so I am confused.

Cheers for any help.
TOM