Transistors in a 5 bit sequencer

[Lincoln]

I'm putting this in the Off Topic Lounge because it is more of a general transistor question than a 5 bit sequencer question.  Have been working on a 5 bit sequencer that has one string of lights out.  Not exactly out, but very dim and not flashing.  I know the jukebox is ok because I can swap in a different sequencer and they all work.  Testing with a volt meter is a little hard do to the fluctuating current, but all strings appeared to be doing the same thing.  I also noticed this sequencer was getting pretty warm around the transistors on the case, or the resistors underneath.  I had checked every other component on this string and appeared to be within tolerances so I pulled the transistor out to test it.


On my resistor tester it showed a current gain of around 100.  I had 5 other of the same transistors out of another sequencer than I am working on.  I had previously checked them and found most had a gain of around 40 to 70.  I swapped one of these in, and it cured my problem.  All lights now work and the sequencer does not get hot.

The specs on that transistor show a max current gain of 150.  


I solved the sequencer problem, but I guess I am wondering why.  The transistor that was causing the problem was technically still good.  Was it too far out of the range of the other four? 

Thanks,
Lincoln Schmeiser

[Ron Rich]

Hi Lincoln,
I would ASSUME, that the transistor in question became "leaky"--but not enough for your tester to catch ? Was that a Seeburg numbered transistor, or an equivalent ? Ron Rich

[Lincoln]

It was a Seeburg numbered transistor. 309441 is the part number. I think a 2N3054 is the equivalent.