Hi all,
I'm trying to get an MK1 Poly 800 back to life. I suspect that the tone
generator chip (IC3) is faulty.
The clocks to pins 19 and 20 look OK, and the envelope inputs E0-E7
rise and fall as expected when I press keys. The power supply pins look
OK too, and the data, address, ALE and ~WR are all clocking nicely.
However, there's nothing much on the footage outputs. They're all more
or less stuck at +5V, although there's a little square wave wobble on
some of them whose amplitude tracks the envelope input.
Is it likely that my TG is busted, or am I missing something else?
Cheers
mark-r
I'm trying to get an MK1 Poly 800 back to life. I suspect that the tone
generator chip (IC3) is faulty.
The clocks to pins 19 and 20 look OK, and the envelope inputs E0-E7
rise and fall as expected when I press keys. The power supply pins look
OK too, and the data, address, ALE and ~WR are all clocking nicely.
However, there's nothing much on the footage outputs. They're all more
or less stuck at +5V, although there's a little square wave wobble on
some of them whose amplitude tracks the envelope input.
Is it likely that my TG is busted, or am I missing something else?
Cheers
mark-r