Porta02 input issue

[Handpanther]

Heya! I have a Porta02 mkII and all 4 channels playback as they should, and the input on channel 2 works fine. Channel 1, however, is dead - no input audio (on 1 or 3), no LED response. I cannot find anything visually the matter on either PCB, and the connecting cables all look intact. Where should I focus my attention to narrow down the fault finding?

Thank you!

 

[Handpanther]

This is a tape machine from 1999. It doesn't have firmware.

I am asking in a DIY repair forum, which would imply an inclination to repair it myself.

 

[Jack Saturn]

Have you traced the signal path on channel 1 to see if the audio signal stops at a certain point? Focus on the capacitors in that path and you should be able to find the problem.

Alternately, have you confirmed that the solder joints for input jack 1 aren't broken?

 

[Handpanther]

I've traced it only visually, mostly because I don't know yet how to do it with a multimeter. I suppose now would be a great time to learn

The solder points on the jack appear fine, and I was initially reluctant to desolder it to check/replace mostly because I didn't want to risk adding another fault.

Thanks for the reply!

 

[Jack Saturn]

I've worked on a lot of Porta02 machines, and usually when there's a problem like you describe, it's a failed capacitor, and not generally one that's obvious to the naked eye. Keep us posted on what you discover!