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(Topic ID: 277345)

F-14 Jet Bumper Problem


By FlaGeek

42 days ago



Topic Stats

  • 8 posts
  • 4 Pinsiders participating
  • Latest reply 42 days ago by bobukcat
  • No one calls this topic a favorite

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#1 42 days ago

I've searched for anyone with exactly this problem and haven't found anything. Apologies if I missed the relevant post.

I've got an F-14 with a Rottendog MPU9211 CPU replacement in it. The only problems I've seen are the jet bumper and the flasher on solenoid 5.

The jet bumper (solenoid 20, transistor Q69) doesn't fire in either the diagnostics or when playing the game. If I have the game in attract mode and ground Q69 the bumper fires. From what I've read that should verify everything from the transistor forward. I've search without success for a schematic for the MPU9211, so I'm not certain what other points to test to trace back further. I've replaced a 6821 that's near Q69 just in case that was bad (U42 was bad when I first installed the board) without getting any change in behavior.

I haven't researched the flasher that isn't working. I only mention it in case there's a known link between these two symptoms.

Any thoughts?

Thanks,
Don

#2 42 days ago

Rottendog have a lifetime warranty as far as I am aware. Contact their support and the guys will help you.

#3 42 days ago

Hmm, this is strange..If you grounded the transistor and it fired, that means the coil, transistor and wiring is ok. That only leaves the board itself.....perhaps you need to go back and look at the board, you may have another component on it that maybe bad. I'm a fan of Rottendog myself...I had a couple of friends who had problems after installing but almost always it turned out to be something else (connectors, ribbon cable etc).

#4 42 days ago
Quoted from kvan99:

Hmm, this is strange..If you grounded the transistor and it fired, that means the coil, transistor and wiring is ok. That only leaves the board itself.....perhaps you need to go back and look at the board, you may have another component on it that maybe bad. I'm a fan of Rottendog myself...I had a couple of friends who had problems after installing but almost always it turned out to be something else (connectors, ribbon cable etc).

Unless they are different on the RD boards grounding the tab doesn't actually test the transistor it just tests the coil, wiring, etc. I would venture a guess that the drive transistor or pre-driver is bad.

#5 42 days ago
Quoted from bobukcat:

Unless they are different on the RD boards grounding the tab doesn't actually test the transistor it just tests the coil, wiring, etc. I would venture a guess that the drive transistor or pre-driver is bad.

Oh okay, but If the transistor is shorted or bad wouldn't the coil be locked on?

#6 42 days ago
Quoted from kvan99:

Oh okay, but If the transistor is shorted or bad wouldn't the coil be locked on?

Shorted yes it would lock on a coil but a transistor can fail open as well.

#7 42 days ago

Thanks. What test would you recommend to see if Q69 has failed open? I've also contacted Rottendog to see if I can get a schematic from them and any advice they have.

#8 42 days ago
Quoted from FlaGeek:

Thanks. What test would you recommend to see if Q69 has failed open? I've also contacted Rottendog to see if I can get a schematic from them and any advice they have.

I'm sorry but I'm not familiar with their boards and don't know what transistor types they use in the game but it should be a NPN and the tab should be the emitter. With that in mind and the game off if you put a meter in diode test, black lead on the tab and the red lead on each leg you should have a forward voltage drop of about .8-1.2V from the base to the emitter and a very high reading from collector to emitter (one leg will be a dead short to the tab as they are electrically connected). I'd suspect you won't see the base to emitter drop and it will be open indicating a bad transistor. Also If you have a logic probe you could probe the base of the transistor (just be careful and don't put the probe on the high-voltage legs of the transistor, could seriously damage it) while the game is in solenoid test mode and see if it cycles, if it does the pre-driver is working and the driver transistor is bad, if not the problem is the pre-driver or further up the logic chain of the board. You'd have to follow that back up the chain with the logic probe if that's the case.

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