OBERHEIM SYNTH

At 10:25 AM 2/25/2009, jim finch wrote:

>Well,It appears to be the Z-80 CPU.With all the chips associated with the D3 line are pulled,D3 still swings between 0-2V.No shorts to ground,or other D-bits,that D3 line just won't swing full TTL levels.
>Question though,all the Z-80 CPUs are either higher clock speed,NMOS/CMOS.Does it matter what Z-80 is used as long as it meets spec?Original CPU is a Mostek.

A higher clock speed Z80-CPU should be fine.  I don't think NMOS vs. CMOS matters in this case either.

>Another question.Have replaced a few of the 6.8uf caps.How critical are the values.Most of the caps. I find are at least 10uf.Acceptable to replace the 6.8 with 10uf.

Probably OK, but it may depend on what part of the circuit they're in.

>And still another question.Why Tantalums as output coupling caps.?I have seen them in some "British" Eq circuits.Unique distortion?

Possibly less change in capacitance over time?

-- Paul W.