From Kenny Balys Sent Thu, Sep 5th 2019, 00:31
From Kenny Balys Sent Thu, Sep 5th 2019, 00:31
Its the audio multiplexer! DMX-88 Equivalent part: PMI MUX-08 Silconix DG508 Harris HI-508A National LFII508 Thats all. On 04.09.19 23:29 , Kenny Balys wrote: > > 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. >> >> >