(Topic ID: 154213)

Which Transistor?

By The99Kid

8 years ago



Topic Stats

  • 7 posts
  • 4 Pinsiders participating
  • Latest reply 8 years ago by The99Kid
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#1 8 years ago

Following the replacement of the entire flipper assembly, I made the mistake of adjusting the EOS stroke while the game was powered on, and inadvertently contacted the lane change switch and now column 5 switches don't work. All related coils work in coil test mode. Additionally, the A/C relay clicks on and off during the test, and all 'A' and all 'C' lamps/coils work in test mode.

So, I believe that i blew the transistor in position Q43. Thoughts?

If so, I've found conflicting info on what transistor should be used to replace the one at Q43.

2N3904 or 2N3906? Or something totally different? I can get these at RS so that would be nice if one of them was the right one...

Any advice is appreciated!

#2 8 years ago

You probably blew at least one of the switch matrix chips by sending solenoid voltage through it.

#3 8 years ago

Manual says 2N3904 for Q43. Same for later System 11 machines too. Where's the conflicting info coming from?

I'd check the resistors associated with Q43 and also U40 and U39.

#4 8 years ago

I'm not sure exactly what those are or where they are...1st pin, very new to them as well as electronics in general...great at mechanical stuff, electronics, I'm learning!

Does the fact that everything works in test mode except the switched tell me anything?

#5 8 years ago

Follow the wiring up the matrix column to the correct transistor.

I made a similar booboo swapping LEDs with power on. I knocked out column (6) on my JP, reading the schematics pointed me first to Q50 (NPN 2N3904) - was shorted on one of the legs to center, whereas the other nearby NPNs were not.

This was the issue, a quick swap fixed my issue & lesson learned. If that did not fix, I was going to look at the next component in the chain.

#6 8 years ago

Page 46 and 47 of your manual show the MPU and list what components are and where they are. Page 60 shows the schematics for the switch matrix. You can see what components are associated with Q43 and trace where the high voltage could have gone.

#7 8 years ago

Thanks all. I'll go by RS and grab some 2N3904 transistors and swap out Q43 first and see if that fixes it. If not, I'll keep moving up the chain!

The reason I asked which one was that on the Marco site, if I look at 'Millionaire' parts only, the only transistor listed is 2N3906, NOT 2N3904...but in several other threads, as in this one, it appears that I should use 2N3904.

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