Dynaco SCA-35 update

I installed the new power transformer in the SCA-35 and got everything wired back up and at first was really psyched to listen to some vinyl again. After a couple of records, though, it became apparent that the new transformer was humming loudly, without too much detectable vibration. There was also a slightly softer hum through the speakers which sounded like maybe a little ground hum. But since everything else was the same but the transformer (previously raided to get my ST-35 power amp going), and I had triple-checked my wiring, the tech at Triode suggested I send it back for a replacement.

I pulled the new trans out and on a whim I installed the xformer that I'd originally pulled out of the ST-35 . Sure enough the fuse blew immediately. Oh, well.

I guess now I could pull the original one back out of the ST-35. The St-35 needs the PC boards re-done anyways - the plastic tube sockets have gotten melty over the years, and the boards are visibly darkened & warped from the tube heat over the years. I have a pair of new brand PC boards sitting in a drawer all ready to go - but I'll need to order new new ceramic sockets and components for that project.

Forced to use what I have on hand, I may just go ahead with the xformer transplant. I recently got my Hafler DH-220 going again so I guess I can spare the ST-35. If the result is being able to listen to some vinyl through the Dynaco's sweet phono section later today I guess it's worth it.

Also, my friend Dave gave me a sweet Bogen gold-face integrated the other day, model AP-30. The phono section is real thin for some reason. I did some tube rolling but no change. It sounds great through the Aux channel, though, very up-front and warm through my EPIs. Hard to adjust the volume at the lower end of the range, though - it begins to crackle and lose balance. This seems to be something that frequently goes wrong with the old amplifiers as the old pots age. It makes sense since the dirt probably builds up most at the end of the wiper face. These early stereo amps often use a ganged (dual) potentiometer which can be expensive to replace and usually involves some tricky soldering.


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