(Topic ID: 181621)

Jurassic Park Switch Column Issue


By dearliza98

2 years ago



Topic Stats

  • 10 posts
  • 4 Pinsiders participating
  • Latest reply 2 years ago by PinballManiac40
  • Topic is favorited by 1 Pinsider

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Topic index (key posts)

3 key posts have been marked in this topic

Post #1 Problem: entire CN8-5 Switch Column is out on my JP Posted by dearliza98 (2 years ago)

Post #3 How to test Q51 Posted by PinballManiac40 (2 years ago)

Post #9 Q51 Transistor Replaced - Resolved Posted by dearliza98 (2 years ago)


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#1 2 years ago

Hey all. My entire CN8-5 Switch Column is out on my JP. It was workin and recently stopped. I have checked everything under the playfield and I believe it is ok.

Then I tested voltage on the CN8 pins on the CPU and noticed that only CN8-5 had a voltage drop compared to all of the others.

Just wondering what I should test next and how to test it with my DMM. Obviously I'd rather repair a diode or transistor than a PIA. I'm just not sure where to go now. Thank you!

#2 2 years ago

Check all voltages at the power supply first to ensure you have the proper voltages going out. If not look for weak or cracked fuse clips. May need to rebuild the power supply.

#3 2 years ago

Measure Q51 (switch drive 5) to see if it is shorted and compare the results to either Q50 or Q49. You're looking for a big difference in ohms to prove Q51 is shorted.

Outer to outer
inner to one outer pin
inner to other outer pin

Part is a 2N3904 transistor.

#4 2 years ago

pinballmaniac40 Thank you for the information here. I purchased some of these transistors and should be arriving this weekend. Not sure that's the problem but they will be on-hand if it is. Can't beat 20 for $1 or something like that.

I have a logic probe arriving tomorrow so hopefully I can diagnose this in the next couple of days. Thanks again everyone.

-1
#5 2 years ago
Quoted from dearliza98:

pinballmaniac40 Thank you for the information here. I purchased some of these transistors and should be arriving this weekend. Not sure that's the problem but they will be on-hand if it is. Can't beat 20 for $1 or something like that.
I have a logic probe arriving tomorrow so hopefully I can diagnose this in the next couple of days. Thanks again everyone.

Just a multimeter set on ohms will test out the transistor for a short, as I mentioned above. It would be good to go through the steps to verify it is at fault before just replacing it.

#6 2 years ago

pinballmaniac40 Thanks again. I'll be checking this out tonight or tomorrow at the latest. Kind of hoping it's a transistor problem b/c I've actually replaced those before. I have a brand new PIA and socket sitting at home but will need a pro to install that as a worst case.

#7 2 years ago

pinballmaniac40 I was able to check the Q51 transistor and I think there may be a problem with the inner pin. The two outers more or less matched the Ohms on the other nearby transistors but the inner/outer test did not. It's a tight fit in there so I'm slightly concerned with my ability to not make matters worse by trying to repair, but hey... I need the practice. Thanks for your help.

#8 2 years ago

Glad to see someone got you pointed in the right direction. Hopefully, that resistor is the culprit! Good luck!

1 month later
#9 2 years ago

I always hate it when people on here get free advice and then never come back to provide resolution on their problem. So here I am with resolution!

Turns out Q51 transistor was shot and just needed a replacement. Everything is working now and the switch matrix on CN8-5 is great!

Biggest lesson I learned was next time I won't spend many hours under the playfield tracing wires and testing diodes without first simply checking to make sure the board is working properly.

Thanks for the help!

-1
#10 2 years ago

Glad you did indeed test it before replacing it. I am happy you replaced it without any issues. Enjoy your game. Thank you for posting the result.

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