All,
I'm in the process of restoring a 20+ years old subwoofer which was sold to me for a few bucks as 'doesn't work, sound is very low'.
After testing the two speakers, the power supply and measuring the amplifier board components, I came to the conclusion that power supply caps are leaking / to be replaced and that one differential input stage transistor is fried.
See input stage schema below which I simulated with ZTX851 and ZTX951. It was initially built with 2SC2389 and 2SA1038. I have one 2SC2389 fried, the rest is measuring ok.
I'm planning to replace the 2 2SC2389 at minimum and wondering if I should or not replace the 2 2SA1038 as well to have the 2 pairs from equivalent series.
Any advice would be welcome 🙂
Enjoy day !
Jean-Francois
I'm in the process of restoring a 20+ years old subwoofer which was sold to me for a few bucks as 'doesn't work, sound is very low'.
After testing the two speakers, the power supply and measuring the amplifier board components, I came to the conclusion that power supply caps are leaking / to be replaced and that one differential input stage transistor is fried.
See input stage schema below which I simulated with ZTX851 and ZTX951. It was initially built with 2SC2389 and 2SA1038. I have one 2SC2389 fried, the rest is measuring ok.
I'm planning to replace the 2 2SC2389 at minimum and wondering if I should or not replace the 2 2SA1038 as well to have the 2 pairs from equivalent series.
Any advice would be welcome 🙂
Enjoy day !
Jean-Francois