(Topic ID: 290741)

Tech: MPSA42 Transistor Equivalent (5A-9216?)

By Goonie

6 months ago



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  • 8 posts
  • 5 Pinsiders participating
  • Latest reply 6 months ago by Goonie
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#1 6 months ago

Hey all.

I'm working on a Bally 6803 display that has the H & J segments out on all digits. I've re-flowed the solder and confirmed it's not a cable issue, so I'm going to swap out the resistors and transistor. I'm having a bit of trouble finding an MPSA42, but Marco lists a 5A-9216 - I assume as a recommended swap. Before I do this and blow something up, I thought I would verify. I can't find much out of the web that shows these are equivalent. Can anyone confirm I can swap these? Looking at the specs on both, I think I am fine, but I'm far from an expert in this field.

Thanks!

Aaron

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#2 6 months ago

Just order MPSA42 from great plains although I am sure the Marco one is fine too.
https://www.greatplainselectronics.com/proddetail.asp?prod=MPSA42

#3 6 months ago
Quoted from Cheddar:

Just order MPSA42 from great plains although I am sure the Marco one is fine too.
https://www.greatplainselectronics.com/proddetail.asp?prod=MPSA42

Oh man, I could have sworn I checked there. Thank you!

#4 6 months ago

Yes indeed an MPSA42 does cross to NTE287.

#5 6 months ago

KSP42 is an equivalent that was made by Fairchild Semiconductor.

MPSA42s were originally made by Motorola (ON-Semi) but discontinued them a few years back.
ON-Semi bought Fairchild, discontinued the KSP42, started making MPSA42s again (KSP42 with a different part number) ... and now they have discontinued them again.

Fortunately, there are still a couple other manufacturers of these left.

#6 6 months ago
Quoted from Goonie:

I'm having a bit of trouble finding an MPSA42, but Marco lists a 5A-9216

5A-9216 is a Williams part number for a MPSA42 transistor.

Swap a suspect MPSA42 with a working one to see if the fault follows the transistor or the display segment.

#7 6 months ago

Thanks all for the information and education. Will place an order and see what happens.

3 weeks later
#8 6 months ago

Hi

Just closing the loop here. So, I replaced all 3 resistors and the transistor controlling H and J, and no luck. However, swapping out the U1 chip did the trick and I am back in business with a fully operational display.

Thanks for the guidance.

Aaron

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