Tech EM: Bally Knock Out Stuck Coils

[Garret]

Working on a Bally Knock Out from 1976. Game kept blowing fuse.
Ohmed out coil on stepper unit on bottom of playfield. The owner said
that he heard a buzzing, but kept playing...Yep..toasty coil. I
swapped the coil out.

After turning the game on and pressing the start button, the stepper
unit coil locks on as well as one of the coils under the chime unit.

Any ideas on troubleshooting would be greatly appreciated. Thanks!

[Carl Witthoft]

Post by Garret
Working on a Bally Knock Out from 1976. Game kept blowing fuse.
Ohmed out coil on stepper unit on bottom of playfield. The owner said
that he heard a buzzing, but kept playing...Yep..toasty coil. I
swapped the coil out.
After turning the game on and pressing the start button, the stepper
unit coil locks on as well as one of the coils under the chime unit.
Any ideas on troubleshooting would be greatly appreciated. Thanks!

You've got some stuck switches somewhere. The chime unit coil is active
most likely because of a stuck switch on the corresponding score (10,
100, etc) relay.
Stepper unit.... well, is the score motor running, as it should during
the reset sequence? Start there.

[Don O]

Yep, Carl is right on as usual... check for a stuck playfield scoring
switch (like in back of a kicker for instance), or possibly a rollover
switch... if you can't figure out the culprit switch right away, you
can tell what value the culprit switch associated with by looking at
which score relay coil is stuck in the ON position... it'll be 10,
100, 1000 pt score coil in the back box I believe for your game...
based on that value, you can pretty much determine more easily which
playfield switch is stuck closed.

Keep in mind that the scoring coil is pulsing both the associated
score reel and associated chime bar. Once you fix the switch spacing
issue you should be good to go.

A good idea is to just turn the game off, visually inspect and tweak
every playfield switch prior to troubleshooting... word of thumb is
about a 1/16th space between each switchblade. A switch adjustment
tool is your friend!

Good luck...

[c***@Team-EM.com]

Post by Garret
Working on a Bally Knock Out from 1976. Game kept blowing fuse.
Ohmed out coil on stepper unit on bottom of playfield. The owner said
that he heard a buzzing, but kept playing...Yep..toasty coil. I
swapped the coil out.
After turning the game on and pressing the start button, the stepper
unit coil locks on as well as one of the coils under the chime unit.
Any ideas on troubleshooting would be greatly appreciated. Thanks!

Yup, that coil was toasty for a reason. Once replaced, the reason most
probably still exists.

I think that's the bonus unit you have there. Those dang Bally's step
the bonus down to 0 and then once there, step it back up to 1000
during the startup/reset sequence. If it's a step-up coil, you may
have a switch stuck closed that would normally cause one bonus to be
added. Or, the end-of-stroke swtich could be broken or out of
adjustment. If it's the step down coil, uhhhh.... I'm not going to
hazard a guess. I know that I hate reading Bally schematics ... but
that's a personal problem. :-)

Keep us posted.
--
Chris Hibler - CARGPB #31
www.Team-EM.com

[Garret]

Post by c***@Team-EM.com

Post by Garret
Working on a Bally Knock Out from 1976. Game kept blowing fuse.
Ohmed out coil on stepper unit on bottom of playfield. The owner said
that he heard a buzzing, but kept playing...Yep..toasty coil. I
swapped the coil out.
After turning the game on and pressing the start button, the stepper
unit coil locks on as well as one of the coils under the chime unit.
Any ideas on troubleshooting would be greatly appreciated. Thanks!

Yup, that coil was toasty for a reason. Once replaced, the reason most
probably still exists.
I think that's the bonus unit you have there. Those dang Bally's step
the bonus down to 0 and then once there, step it back up to 1000
during the startup/reset sequence. If it's a step-up coil, you may
have a switch stuck closed that would normally cause one bonus to be
added. Or, the end-of-stroke swtich could be broken or out of
adjustment. If it's the step down coil, uhhhh.... I'm not going to
hazard a guess. I know that I hate reading Bally schematics ... but
that's a personal problem. :-)
Keep us posted.
--
Chris Hibler - CARGPB #31www.Team-EM.com

Thanks! I had an epiphany last night laying in bed and thought it had
to be a switch on the score reel causing the issue. The reason I say
that is the guy who was playing the machine said that he heard a
humming sound coming from the middle of the playfield but kept
playing!!! Next was a small puff of smoke followed by the game
shutting down (blowing a fuse)

A little off topic, I had the opportunity to help shop out a Captain
Fantastic this evening that has been wrapped in plastic in a temp
controlled warehouse since 1981! It was absolutely gorgeous! Not a
spec of dust in the cab! I cleaned the reels that only had a light
coating of dust. Of course, the jet bumpers on the gate were gummy,
but that was remedied quickly. Fired up the game...WOW!! Played
smooth as silk... Too bad it wasn't mine. Backglass was absolutely
perfect and plastics looked brand new. Backglass had the stars by the
way. I'll sleep well tonight :)