Spl dynamics d92

Received this amp. Repaired from the previous owner.. Bad repair, anyway it seems it works. The new owner mentioned, that the amp hasn't the power it should have. Found a damaged master /slave switch.
I have oscillation at each channel..
The amp is out of the heat sink, if I apply power, the r-ground resistor starts smoking.. What can cause this? Some leaking?
 

Attachments

  • IMG_20220114_183134.jpg
    IMG_20220114_183134.jpg
    472.4 KB · Views: 13
  • IMG_20220114_183138.jpg
    IMG_20220114_183138.jpg
    555 KB · Views: 14
Received this amp. Repaired from the previous owner.. Bad repair, anyway it seems it works. The new owner mentioned, that the amp hasn't the power it should have. Found a damaged master /slave switch.
I have oscillation at each channel..
The amp is out of the heat sink, if I apply power, the r-ground resistor starts smoking.. What can cause this? Some leaking?
Maybe a shorted input cap?
 
No, I haven't measured the voltage across. I twisted a lot, maybe that was the reason . For safety I removed the rectifiers, and used a dual supply. The amp looks at this stage fine to me.. Each bank at the audio stage has a good square wave.. No smoke, no current draw..
 

Attachments

  • IMG_20220115_204117.jpg
    IMG_20220115_204117.jpg
    696.9 KB · Views: 3
One question about the audio part. First picture is high side gate, black probe at sec. The amplitude is a little lifted to positive rail. Is this normal, or something leaking? Second picture is low side drain.. Is normal amplitude.
The last picture is ps gate. Frequency about 28khz..should be also okay
 

Attachments

  • IMG_20220118_171300.jpg
    IMG_20220118_171300.jpg
    592.8 KB · Views: 3
  • IMG_20220118_171316.jpg
    IMG_20220118_171316.jpg
    586.7 KB · Views: 2
  • IMG_20220118_172330.jpg
    IMG_20220118_172330.jpg
    549.5 KB · Views: 3
Last edited: