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Old 06-21-2021, 04:38 AM   #1
dicky96
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Default B1186A Digital Transistor?

Hi guys
I have this power transistor, it's taken from a Class G Power Amplifier. I already found two short circuit diodes on the Faulty Channel, but I decided to remove the other transistors and test them.

They all test OK but this one is marked B1186A and on my Peak DCA55 it analyzes as a PNP Digital Transistor (which I believe is a transistor with integral base resistor) but if it is a 2SB1186A then it should detect as a regular PNP Transistor.

Having said that I put it in my LCR-4T semiconductor analyzer and that just says it is a PNP Transistor.

So I am a bit uncertain if this actually is a (2S)B1186A and if it is definitely OK or faulty.

Yeah I could desolder the one form the the other (working) channel but the amplifier modules take some effort to strip down and I would rather not have the hassle if I don't have to.

You can see which device it is here - it's the one clipped to the front end of the heat sink you can see me checking it here:

https://www.youtube.com/watch?v=kbPynpQefz8 (28mins 30secs)
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Old 06-21-2021, 06:54 AM   #2
stj
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Default Re: B1186A Digital Transistor?

the logo looks like Rohm which makes it the 2sb part
most "digital" pre-biased transistors contain 2 resistors anyway, not one.
what does it look like on a multimeter diode-test?
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Old 06-21-2021, 11:26 AM   #3
R_J
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Default Re: B1186A Digital Transistor?

I agree, it is a Rohm 2SB1186A, Usually paired with a (NPN) 2SD1763A
Most of the "digital transistors" I have seen are small case low power, not to220

Last edited by R_J; 06-21-2021 at 11:43 AM..
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Old 06-21-2021, 12:13 PM   #4
dicky96
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Default Re: B1186A Digital Transistor?

OK thanks. I ordered a couple from Ali as I was placing another order anyway for the faulty diodes needed to fix this amplifier, plus an M2 adapter card for one of my PCs so combining the postage with other things, they only cost me 70 cents for two 2SB1186A
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