Hi folks, I apologize if this is a basic question, but I'm an EM guy and don't have to deal with all these fancy new electronic gizmos like transistors

Anyway, both Clay's guide and pinwiki state when you test a transistor, you put red lead (DMM set to diode) on collector and then black to each pin (E and B) both will read around 0.5 to 0.7.

But if I test my stock of new MJ2955's they only give a 0.5 reading on one pin. Is that correct? Is both pins giving a reading only when the transistor is in circuit?

thanks!

#2 2 years ago

PIP

Quench

Pinside member

8y 114K 8,060

OP
Quoted from 4Max:
Anyway, both Clay's guide and pinwiki state when you test a transistor, you put red lead (DMM set to diode) on collector and then black to each pin (E and B) both will read around 0.5 to 0.7.

This is incorrect for a MJ2955.
For a PNP transistor (which the MJ2955 is) you put the black meter lead on the "base" pin and should measure around 0.6V with the red lead to each "collector" and "emitter" pins. Specifically with a MJ2955 you should not measure anything between the collector and emitter no matter which way the meter leads are oriented.

#3 2 years ago

DAN

4Max

Pinside+ Frequent

10y 53,900 471

Ah. Understood!! Thanks Quench

Reply

Wanna join the discussion? Please sign in to reply to this topic.

Hey there! Welcome to Pinside!

Donate to Pinside

Great to see you're enjoying Pinside! Did you know Pinside is able to run without any 3rd-party banners or ads, thanks to the support from our visitors? Please consider a donation to Pinside and get anext to your username to show for it! Or better yet, subscribe to Pinside+!

This page was printed from https://pinside.com/pinball/forum/topic/testing-a-mj2955-out-of-circuit-only-one-leg-gives-reading and we tried optimising it for printing. Some page elements may have been deliberately hidden.

Scan the QR code on the left to jump to the URL this document was printed from.