replace all the things - Ultrasonic bath repair

Thread Starter

Paul van den Bergen

Joined Dec 15, 2016
Hey Folks,

I've got an ultrasonic bath I'm attempting to repair....
Dual transducer, 2 x 50W

Specifically I'm trying to understand the following transistor code/designation


I've found a few references to similar looking components - "fast" switching, relatively high voltage, for power and similar applications...

the question is - what do they mean by fast, what do they mean by high power?

it's an ultrasonic bath so fast switching means 100's of microseconds or less, not GHz...
high power? since it's clearly exceeding the 3A fuse capacity, I suspect getting this right is probably important...

Is there a translator for transistors like capacitors and resistors???

History so far:
One transducer stopped first and a few weeks later the second one stopped. Not really surprising.

cracking it open it was pretty clear some resistors (low ohm - 0.1 -> 10, ~6W) were kaput. Replaced all but two 10 ohm resistors that look to be OK. also replaces a 10k resistor that triggered the high power switching.

at this point the machine turns on and the LCD control panel works again. The instant I start the occillator circuit the fuse blows. Replaced all the capacitors.

Not sure what to do next - replace the last 2 resistors. on my list. replace the 4 transducers - next on my list. Buy another bag of 3A fuses? yep...