(Topic ID: 81357)

Firepower - Pop Bumper Staying Engaged

By Jeremecium

5 years ago

Topic Stats

  • 7 posts
  • 3 Pinsiders participating
  • Latest reply 5 years ago by barakandl
  • Topic is favorited by 2 Pinsiders


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#1 5 years ago

I have a new (to me) Firepower which now has its top right pop bumper staying engaged from the start of a game. I checked to make sure the leaf switches were not contacting and they appear to be spaced adequately. What else should I check that could cause this?


#2 5 years ago

Shorted electrolytic cap across the switch. Shorted TIP-102 on the driver board. Bad TTL 7402/7408 on driver board.

Start at the solenoid and check/replace the electrolytic cap across the solenoid switch.

Next test the TIP driver transistor. Power off. DMM set to diode test. Black lead on middle leg/metal tab of associated TIP transistor. Probe the outer legs with the red lead. You should see .4 to .6v. If not replace the tip driver transistor.

Next test the associated 7402 and 7408 TTL ics. Power off. DMM set to diode test. Red lead on ground. Black lead touch the associated pins on the 7402 and 7408 ICs. Again you should see .4v to .6v. A lower or short is indication of bad TTL chip. Use the schematic on IPDB to find the associated 7402/7408 pins.

#3 5 years ago

Thanks, barakandI. I forgot to mention it has the Rottendog MPU 327 board.

#4 5 years ago

does it score if you close the switch? or stuck in scoring mode?

#5 5 years ago
Quoted from pinballlizard:

does it score if you close the switch? or stuck in scoring mode?

Remember, pop bumpers in williams games are "special solenoids". The scoring switch circuit is completely isolated from the driver circuits. Whether or not it scores will have nothing to do with why it locks on.

If it was a WMS factory driver board i could help you better. I assume rottendog drives things in a similar fashion, but i really have no clue.

#6 5 years ago

barakandI, I noticed one of the always-open leafs on the pop switch is missing. I am quite certain it has been like this since the broken leaf is nowhere to be found. It was working as it should until today.

#7 5 years ago

That is the scoring switch with the broken blade. Your pop bumper in theory should still pop with that blade missing, just receive no points. That electrolytic cap, barrel shaped thing, in top left of picture is the cap to check/replace.

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