Have I tossed out GOOD HOTs?

TSB

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I got some new 2sd870 and thought I'd test them before dropping them in. Turns out they had the same readings as the one that I thought was bad. (Pic1)

I searched for a datasheet that had a schematic of the part, and saw that it has a resistor in it... (pic2)

How do you test these? I seriously feel stupid right now.
 

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Hi TSB, the top 2 photos in pic 1 is the correct way to test that type of transistor & readings look good.

DMM set to diode test/continuity, black lead to case, red lead to one leg then the other, should read about .300 to .600 on each leg if it's good, very low reading .00X or continuity beep if it's bad.

If you place a probe on each leg at the same time and get a short/continuity beep, that's normal & doesn't mean it's bad.
 
Thank you! That's a huge help!

I found actual schematics for most of the other TO-3 parts I've replaced, and it looks like they were standard transistors (except on the G07).


Hi TSB, the top 2 photos in pic 1 is the correct way to test that type of transistor & readings look good.

DMM set to diode test/continuity, black lead to case, red lead to one leg then the other, should read about .300 to .600 on each leg if it's good, very low reading .00X or continuity beep if it's bad.

If you place a probe on each leg at the same time and get a short/continuity beep, that's normal & doesn't mean it's bad.
 
the top 2 photos in pic 1 is the correct way to test that type of transistor & readings look good.

All his pics are the correct way: you also need to reverse the probe to test the junctions as bad junctions could give readings both ways. And yes, HOTs with a built-in damper diode have a 40-50ohm resistor across base and emitter so you can only measure resistance across those if it's good.
 
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