Electronics > Repair
ultrasonic cleaner MH-060S, replacing transistors [fixed > broken again]
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elektryk:
2SC3320  also has VCEO=400V

From my experience MJE13009 are enough to drive 2 transducers 60W each.
htm:
i've got an update and wondering what to do next;
transistors
i ordered a few SC3320 from aliexpress.com(€3.08 for 5 ???), ordered a few BUV48A(€4,24 for 1) from tme.eu and i salvaged 1 good transistor from the main board.
Then i used my new component tester :clap:. Turns out the AliExpress ones are all seen as a Diode!? (see attached picture)
How can that be? i mean, how wrong must the component be for the component tester to think it's a diode?

transducers
I measured the resistante between the two leads going to each set of 3 ultrasonic transducers. They show open loop.
But when in 'voltage meter DC' setting and connect the black lead to the black probe, and tap the red wire with the read probe, then the measured voltage increases with approx 10mv per tap, until it reaches 400mV and it resets. That happens for both sets of transducers. Not sure what that says though :-//

what next?
Should i just replace the broken components (transistors, fuse and diodes) and give it a go 🙈(after filling up the tank)
or is it better to first check if the transformers/inductors are still Ok. i'm not sure how to go about it though..
i have a simple function generator and a basic analog 10Mhz scope. Could i do something with that?
fzabkar:
Perhaps the Ali parts have a C-E damper diode? I would perform a B-C and B-E diode test with your DMM.
htm:
@fzabkar
Afaik, the C3320 has pin layout: 1(B) 2(C) 3(E)
The diode tests show:

BC
black on 1, red on 2 = OL
red on 1, black on 2= OL

CE
red on 2, black on 3 = OL
black on 2, red on 3 = 0.488V

BE
red on 1, black on 3 = OL
black on 1, red on 3 = OL
fzabkar:
Those Ali parts are fakes.
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