From Kenny Balys Sent Wed, Sep 4th 2019, 23:27
From Kenny Balys Sent Wed, Sep 4th 2019, 23:27
The paper crackle / shredding seems to be gone now.
I replaced U12A - TLO84 with a new TLO74. I had no 84's on my bench so I that is
why the 74.
Its a pure audio stage so the '74 should be ok.
Several caps were replaced.
No more paper crackle.
Next problem, there is still leakage of the main mix on all the individual outputs.
Is this intentional? Does anyone know?
I am looking at the schematics in the service manual and it looks like a summing
resistance
mixer for the "MIX OUT" and there is nothing there stopping leakage of the
various signals
back to every single output.
I cannot tell if this is just the way my machine is but if I believe my eyes and
the schematics
it looks as though all Drumulators do this.
It appears that I could cut out the "12B" 10K resistor bank and have total
isolation of the outputs,
sacrificing the main out.
Any Drumulator comments?
Would love to hear from any Drumulator users.
On 04.09.19 21:05 , Kenny Balys wrote:
>
> Hi AH,
>
> My drumulator is putting out the Mix Out on all outputs.
>
> There is also a paper shredding crackle that comes occationally.
>
> I suspect the TLO84 opamp on the final output but I cannot see how the
> "Mix Out" is bleeding back to all the outputs.
>
> The last stage before the Mix Out amp is a resistance summing mixer.
>
> Any tips most are most appreciated.
>
>