Vintage Synth Repair

I picked up a junked VP-330 MK1 that belonged to Procul Harum, It got put in a loft for 20 years and basically was a mess...both physically and electrically.

Snapped off pots, sliders...wrecked side panels, rusty etc..

Most of the faults lay on the chorus/output board.. bad BA662's, SAD1024 that modulates the Human voice and vocoder..(before it goes into the user selectable stereo SAD512 Ensemble circuit) 

Also it had a bad SAD512D in the ensemble circuit...I couldnt find any for sale and I had a SAD512 16 pin version and as I thought it was the same but in a different package, it would be an easy mod...however I quickly discovered that the 16 pin SAD512 does not have the internal clock driver circuit like the 8 pin version....dammit I thought..and so a 5 minute job turns into a marathon :o)

I looked at the circuits and realised all it needed was a cmos D type flip flop (4013) added between the transistor clock out and the SAD512..

So thats what i did, built a little converter circuit on bread board (consisting of a 16 pin SAD512 and a 4013 in sockets) and hardwired it into the orignal SAD512D space on the board. Works like a charm.

(Seems the 16 pin is available much more than the 8 pin version, so if anyone wants a copy of my very crudely hand drawn circuit let me know!)

So that was that I thought, calibrated the synth properly and it sounded great..I thought..until I tested it in stereo!! No ouput from the left channel! Yes two more SAD512D's have died on that channel, hence no output...boohooo..

So now I need two more...has anyone got any they can sell me...ideally SAD512D 8 pin to save me building more adapters! I will gladly take the 16 pin ones too though.

Please let me know, Phil.