Vintage Synth Repair

Hi again all,

You may remember I asked about a Korg Poly 800 with damage from
a leaking battery a few weeks ago. Well, the bicarb and toothbrush
technique has cleaned it up reasonably well, but there are other
problems now.

The first is that the CPU seems to be faulty - on reset the address
and data lines, ALE and ~RD all pulse madly, but the ~WR line doesn't
do anything. After a short while, the lines go into a regular
pattern as if the CPU is in a fairly tight loop doing nothing.

The CPU is an 80C85. Is this chip still in production or does
anyone know of a surplus outlet who'll sell a one-off at reasonable
cost?

Cheers

mark-r