(Topic ID: 227987)

Bally BMX Magnet Issues

By Mikespinball

8 months ago

Topic Stats

  • 7 posts
  • 3 Pinsiders participating
  • Latest reply 8 months ago by chas10e
  • No one calls this topic a favorite


Linked Games

  • BMX Bally, 1982
#1 8 months ago

Hello Pinsiders,
Working on a BMX pinball machine. Bring this one back from the dead. Have installed a new Alltek MPU board and cleaned up the playfield along with adding LED's. Machine boots up and plays. Only issues I am having is the 1amp fuse under the playfield keeps blowing. This fuse is connected to all the coils on the underside (kickers, kick outs, and drop target reset) with the exception of the flippers. It appears that I have traced it down to be an issue with the magnet under the playfield. That is if I disconnect the magnet on the underside of the playfield the machine plays fine with no issues. I have checked the transistor that is associated with this magnet on the power driver board and it appears to be no problem. (checks out with the diode check on the meter). Also the diode that is connected with the magnet also checked OK (incoming power on the underside of the playfield). Thinking this is a magnet issue, I replaced the magnet. Again same issue (blown fuse). That is when the rollover is activated (turns on the magnet) the fuse blows.
I am a bit of a loss here as to what to check out next. Can anyone jump in and suggest what to check next.


#2 8 months ago

Is it a Slow-Blow 1A fuse your using ? ...only thing I can think of

#3 8 months ago

No its not a slow blow fuse, just a 1amp fuse. Got tired of using them (a bit most expensive) until I figure the issue out as the magnet coil with not even come on when the rollover switch is activated. Would this be the cause?? It was blowing the slow blow fuses first and I ran out of them and had a hard time finding them local. Any other suggestions?

#4 8 months ago
Quoted from Mikespinball:No its not a slow blow fuse, just a 1amp fuse

That's going to be a problem. Coils have a high initial surge when they are activated that's why you need a slow blow fuse. You should order up a bag of them or your going to go though a bunch of fuses.

The magnet looks to the game as another coil so if activating it blows the fuse then it's probably a problem with the coil or the way it's wired.
Youll have to go back to using SB fuses to check this. Since you installed a new magnet have you tested with an SB fuse?

Worse comes to worse you may have to fuse the magnet separately with a higher value fuse.

#5 8 months ago

You can get a current reading from a multimeter usually up to 10 Amps DC using meter in series with the circuit.

A friend of mine has a BMX & I'll ask his recommendation ... cool game

#6 8 months ago

Hello, update: It was the magnet coil and the fuse. Once I replaced the magnet coil and replaced the fuse with a 1amp slow blow the magnet coil started working. Thank you all for the input and help!


#7 8 months ago

Sweet!!! My friend said he hadn't had any troubles with his. He said proper sized fusing would be important so the magnet doesn't burn the playfield

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