Realistic STA-120, 1972, 60WPC Re-Biasing, made by Hitachi

Biasing and adjusting the Realistic STA-180 from 1972, I’d estimate around 60 WPC based on transformer size and overall power consumption. This was marketed at a much higher spec and has some folklore and I’d love to hear more about this receiver. Made by Hitachi.
It’s always been a solid performer since I bought a couple years ago. Since I’ve been re-biasing everything these days I’m finding out all my vintage receivers are performing better now and this is another.
Could not find the service manual, but Audio Karma had a great post from someone who explained the process. There’s an intermediate voltage that needs to be adjusted, and then there’s actual biasing.
Intermediate voltage was only off by like one volt, no big deal. But the biasing was off by 15mv for one channel and then 8mv for the other.
I’m getting incredibly better power out of this and it’s louder with the clipping point at a much different spot than before.
Probably needs a complete recap, but I’m not going to do it now.
Here’s the first class quality video 🙂 you can stay and watch the rest if interested in the details .

[@TheKeymaster316]

You know it has some decent power when I can hear stuff vibrating and the volume looks like it’s maybe on 2. 😅

[@xruraldustx]

Hi, Mark. Sometime in the future, are you able to do a general cleaning guide video for vintage receivers based on your process and any tips you have?

[@davismv]

Thank you for the comment. This is a great idea. I will do this soon. For example, I use two different paintbrush types with a vacuum attachment. And I have a trick that gets rid of scratches, it’s simply a little bit of WD-40 on a paper towel wiped on a plastic surface. I will do something soon thanks.

[@xruraldustx]

@@davismv Awesome! I didn't know how big of an undertaking it would be but I appreciate it. I have a vintage pioneer receiver that's in use but needs cleaned up / maybe even slightly reworked inside and I'm nervous about even in general how to do it safely and the right way.

[@davismv]

Please see the video I uploaded tonight on February 27. I will walk through some of the things that I do to clean up the receivers.

[@xruraldustx]

@@davismv I already watched it this morning while eating my breakfast 😋. Thanks, Mark!