Otari MTR-90 MKIII Tape Path and Nonerasure !!! SOLVED !!!

[abbey road d enfer]

hi
finally back to this erasure problem
now i get the current driven idea
but what is the benefit of that over a regular vca ?

I would think the reason is a 13600 costs pennies and is multi-source. VCA's are $ and single-source.

in this erase amp circuit there are small chokes in the psu rails
on one of the non working cards the neg. rail choke is open

Missing a rail is a good reason why the circuit wouldn't work.

  would harm any thing if i jumper across the choke just to see if that card works ?

No. Just don't expect the channel to work up to spec.

  maybe using the same value resistor ?

I would think the DC resistance of these inductors is a small fraction of an ohm. Just use a piece of wire.

 

[digitall2000]

thanks
abbey road d enfer

just checkin so i'm not doin' the one step forward two steps back thing

and now a big thank you to all that helped me, the erasure problem is fixed
3 OTA's  IC401
2 Driver amps  IC402
1 PSU line choke  L601

again thanks for all your help

oh yeah now im back to this:
https://groupdiy.com/index.php?topic=68359.msg881590#msg881590
or should i have started a new thread?

lance