[Mark-sf]

I just acquired a vintage Stax SRD-X Adapter that appears to not be generating bias voltage. I am a tech and am looking to repair it before finding it a new home. Does anyone have a picture of the circuit or a schematic source before I dig in?

 

[spritzer]

Just open it up and retrace it from the bias pin.  This was a very simple beast based around automotive chip amps and transformers. 

 

[Mark-sf]

I did some preliminary troubleshooting and it appears that the amp section is fine but the bias oscillator is not working. It uses a 2SC1213 NPN transistor that I am having a hard time finding an equivalent. Does anyone know if a 2N4401 can be substituted or have another suggestion? 

 

[spritzer]

It's a pretty generic part so plenty of subs.  Ebay is also littered with them and I doubt they are fakes given how cheap it is. 

 

[Mark-sf]

Thank for the tip! I hadn't even thought to look on eBay.