API Channel Strip MIC/LINE/INST selection issue

[tadejm]

Hello!

I have a flooded API The Channel Strip under repair.
The entire unit is cleaned and in principle works, but the problem is with the MIC/LINE/INST selection (API 512 C mic preamp).
(the same switch switches between the three - MIC/LINE/INST. The switch itself is ok, it works with HEF4017bt counter, ULN2803A and a lot of relays).

LINE and INST selection works ok, but does not switch to MIC selection... What would be the problem? Relays?
I was sure that it was faulty HEF4017, so I replaced it with a new one, but doesn't work.

Does anyone have a schematic of this unit?





Thanks!

 

[jensenmann]

AFAIK our member Majestic12 is an API factory trained tech. Maybe he can help.

 

[Majestic12]

Hi tadejm, please send an email to [email protected]
I'm sure I can help you with this issue.

Best,
Markus

 

[tadejm]

Hi tadejm, please send an email to [email protected]
I'm sure I can help you with this issue.

Best,
Markus

Thank you!! I'll send an email.

 

[tadejm]

Hi tadejm, please send an email to [email protected]
I'm sure I can help you with this issue.

Best,
Markus

Hello, Markus.
Did you get my email?

 

[Majestic12]

Yes, I have already sent you some more information.