Hello!
My name is Daniel and I hope you're all doing well.
I am new to this world and I don't really know a lot about electronics.
Been having trouble with an amplifier and I narrowed it down to the transistors, which I can't identify in order to substitue them.
Are you able to help me?
Any leads will help!
Thanks from the bottom of my heart,
Daniel.

 

Welcome to AAC!

They appear to be house marked and the only thing we can tell you is that they're all the same polarity and likely NPN. You can determine polarity by checking junction polarity using a diode tester. You should be able to do it in-circuit; I've done it many times using a continuity checker that consists of 2 AA batteries and a flashlight bulb.


Note that the pins aren't centered and this view is from the bottom.

Have you tried searching for a schematic? A model number might help, as a manufacturer would tend to use similar circuits.

EDIT: Since you think some of the power transistors are bad (how did you determine this?), some may have bad junctions and you'll need to test until you find ones that have good junctions. If it isn't obvious, make sure the unit is unplugged.

 

Please do not start replacing components yet!! Only real illuminatti can do.

How did you narrowed down to the transistors?

What type of amplifier is that? Two channels?

Get the schematic and not less than 20 pictures taken in daylight but not under the sun. Fresh battery for your multimeter.

Ultra sound?

 

Branson Sonifier?

 

Hello once again, thank you a lot for your quick answers!


I'm sorry for my vague description of the hardware. So, it is a Fisher Scientific Sonic Dismembrator Model 500 AMPLIFIER (basically a Branson Sonifier just like Ylli remarkably said). And yes, it is used to generate ultrasounds like atferrari noted.

I narrowed it down to the transistors as one of them is way darker than the other 5 (the one circled on the attached image) which leads me to believe it is fried.
The Amp turns on and everything seems fine, you can hear the relay working but it can't transmit power.

I tried to search for a circuit board of the machine but unfortunately I had no success.

I also found these on sale :
https://www.google.com/url?sa=t&sou...BBAB&usg=AOvVaw3LPd0p5RcYHzu5VwAdRFdg&ampcf=1

The only difference I found is that the ones on my Amp are 020L and these are 020K. Tried to find the difference but without success.

Attached you will find some more pictures of the machine. I couldn't find any noticeable corrosion nor anything abnormal. Are you able to point something out?

Once again, thanks you so much for your leads,
Daniel.