Looking good so far - but did I miss something? What did you do to get rid of the 31VDC offset you had before?
Well i believe the issue was that i replaced the Q10 emitter resistor from 300 to 600 ohms. I put it back to 300 ohms.
I curve traced each output. Family of curves were spot on. Also, Betas were all within 0-4%.
I plan on listing all components changed and replacements that i used.
The left side is using the 0379 version board. Looks very similar to 1078 board. It’s working, but I suspect it’s a matter of time before fails occur. I’ll at least replace the ecaps. The outputs need new thermal grease and micas. If hfe’s are off i may update outputs while the board is out.
I was pissed about the resistor mix up. But it was a good exercise. I have access to power curve tracer so it was a good check on the outputs nonetheless. This is my first look at this amp. Distortion levels coming in below spec and power numbers over freq look solid. Running both channels continuously have Rms numbers well over spec.
I have it burning in over night.
Left channel should be wash rinse repeat. But keeping the possibility of surprises open.
Thanks to fellow diy’ers with interest and helpful suggestions!
I did not replace main caps, bridge or power switch.
Fyi…….
Parts/hardware totaled ~$250 for Right channel only. This includes Tax and Tariffs(*******).
Left channel in with minimal hiccups. Balance between channels within 0.5-1%
This was being used as a garage step stool/ door stop. Good to see it will be back on the rack. 👍
Temp on both-sides(L/R) ~42/44C. Approx 1.5 hrs. Bias is approx 80mV. Unit is fully closed to get equilibrium between sides.
100Wrms continuous L/R channel
Misc.
~117Wrms
~45Wrms
This was being used as a garage step stool/ door stop. Good to see it will be back on the rack. 👍
Temp on both-sides(L/R) ~42/44C. Approx 1.5 hrs. Bias is approx 80mV. Unit is fully closed to get equilibrium between sides.
100Wrms continuous L/R channel
Misc.
~117Wrms
~45Wrms