Molten Firepower 2 flipper coil

[robm]

I sold my Firepower 2 to a bloke last weekend, and he rang to say the flippers weren't working, went over and the Flipper power supply fuse (F2) was blown.  I then had a look at the coils and the left one was totally molten inside, so the plunger couldn't move up.  I tested the flipper transistor(2N4401 - Q13 out of circuit) and it seems to be fine. 

I removed the offending coil and taped the wires from it, put a new fuse in and fired the machine up, right hand flipper works fine and fuse does not blow when either flipper buttons are pressed.

Is it safe to assume that either the coil died, or the diodes on it failed and caused the problem, so with a new coil it should all be sweet? or do i need to investigate further?

[FirePower]

The flippers on this board are enabled by a relay, so the transistor you tested I'm guessing is just the one to enable to relay. Nothing you can do to it that I can think of will burn out a flipper coil. If it fails open then no flippers work, if if fails closed then the flipper relay is always on, but still needs the flipper button pressed to get the flipper to activate so it's not the problem.

The coil diode is a device to protect the power supply against freewheel reverse voltage spikes when the coil is de-energised, so it won't cause coil problems.

If the coil melted I'd look really carefully at the EOS adjustment. If it's not set properly then the full current through the coil will burn it out, this is most likely your problem I'd say.  Much less likely, but possible, is insulation failure on the coil windings causing a short and then overheating.

[Strangeways]

I would agree that the EOS  would have most likely been the culprit

[ajlaird]

Yes, been there, done that - first thing to check is EOS!

[beaky]

+ 1 eos
make sure it is opening correctly, also hold the flipper button in and try wriggling the flipper to make sure the bush and linkages arn't worn to the extent that when the ball hits the flipper the eos doesn't close again.

[robm]

I think you guys are onto it!!

I noticed the bushing had a bit of slop in it, so will need to make sure its right (i think there may have been some wrong screws in there...), readjust EOS and replace coil once it arrives.

Thanks heaps

[beaky]

I think you guys are onto it!!

I noticed the bushing had a bit of slop in it, so will need to make sure its right (i think there may have been some wrong screws in there...), readjust EOS and replace coil once it arrives.

Thanks heaps

a bit of slop is acceptable but to much may also cause playfield damage (the end of the flipper bat will start to drag on the playfield)

[robm]

Replaced the coil, double checked the EOS, played it for about 10 games and everything was sweet - i'm assuming that maybe the coil's life was just at its end.... Only thing i noticed was that both EOS's give a decent spark when they open.

Now onto the next problem - see the Hook thread...

[ajlaird]

Replaced the coil, double checked the EOS, played it for about 10 games and everything was sweet - i'm assuming that maybe the coil's life was just at its end.... Only thing i noticed was that both EOS's give a decent spark when they open.

Now onto the next problem - see the Hook thread...

Be warned re sparking: on my Cactus Jack's I have had problems with the RHS flipper switch contacts 'arc-welding' together and holding the flipper on. If the EOS contacts look pitted I would replace them.

[beaky]

Replaced the coil, double checked the EOS, played it for about 10 games and everything was sweet - i'm assuming that maybe the coil's life was just at its end.... Only thing i noticed was that both EOS's give a decent spark when they open.

Now onto the next problem - see the Hook thread...

. If the EOS contacts look pitted I would replace them.

+1 on the pitting

[robm]

This problem has happened again - going over to have a look at it today - hoping the problem is as you guys suggested the EOS needs to be replaced.

I do seem to recall there was a capacitor on the cabinet flipper switch, that looked a bit dodgy (one of the legs had a blob of solder right near the green top part).  Does this do anything important and does anyone know what size/type it is so i can grab one on the way out and replace it?

Thanks

Rob

[Ballywannabe]

Most likely the EOS, but you should blow a fuse before the coil melts.  Check the machine has the right flipper fuse value, they are heaps cheaper than coils!

[ajlaird]

Most likely the EOS, but you should blow a fuse before the coil melts.  Check the machine has the right flipper fuse value, they are heaps cheaper than coils!

That is a really good point. Check and double check the fuse values. They are so often wrong.