Roberts 770x Mic and Line Inputs

[Siegfried Meier]

Hey guys,

Just acquired one of these in decent working condition.  I'm not interested in tearing it apart to make it work as a mic preamp only, as the motors and tape portion work.  However, I seem to only be able to get signal on the phono inputs.  The line and mic inputs have absolutely nothing.  The machine is in record enable mode, and no matter what I do I can't get signal.  I've even purchased  new EF86 tubes thinking that was the problem, but no dice.  Is there a trick mode or something special I'm missing to make this work?

Thanks everyone!
Sig

 

[lassoharp]

It sounds like the switch isn't making proper contact for some reason.    Did you check for both rec/pause mode and record with the tape running?

I know that the switching depends on a mechanical movement so there is the possibility that a spring came loose  or something else to make it not actually throw the switch.  You can open it up and manually move the switch.

Putting in a new EF-86 would have made no difference because both the phono and the mic pre use that tube so if the phono is working then the tube is "ok"