(Topic ID: 232557)

Xenon: Interminent Coil Pulsing

By JeffZee

1 year ago

Topic Stats

  • 12 posts
  • 6 Pinsiders participating
  • Latest reply 1 year ago by frenchmarky
  • No one calls this topic a favorite


Linked Games

#1 1 year ago

This problem is so highly intermittent that my observations are rather limited. I've seen this maybe three times in the last few years. First the game was sitting in attract mode when I heard a soft clicking sound. It kind of sounded like the coin lockout coil, but it wasn't. The sound stopped before I figured out anything else. It happened again a few months later. Then it happened again while I was playing the game and this time I saw it was the #1 drop target coil. I thought that maybe the #1 switch was dirty, but that has nothing to do with it. When the game wants to drop a target, it fires the coil only once and doesn't care if the switch closes. The coil is attached to Q1. I poked around and couldn't get it to do anything odd. I tested Q1 and the associated resistors and diode. All readings were comparable to adjacent circuitry. If there is an intermittent circuit problem, I'd think the pulsing would be more random. The pulsing is steady. Maybe one pulse per second. It pulses for a few moments and then stops. And why would it pulse in attract mode?

I've had this game for ten years and this problem is relatively new. In early 2017 I installed an Alltek MPU due to battery corrosion. When I bought this game the battery was already cut away and the board looked clean. But over the years it started growing fuzz around the lower left corner and acting flaky. I don't recall if I ever saw this pulsing problem with the old MPU. The MPU connectors were re-pinned for the new Alltek board. Years ago I re-pinned the driver board connectors and replaced the header pins. I also did the usual driver board ground mods, but I haven't recapped anything.

I really don't want to shotgun this because the issue is so intermittent. I'd like to first figure out how to duplicate the problem. Any ideas? Thanks!

#2 1 year ago

Bump for the weekend crowd...

#3 1 year ago

Did it do the same steady pulsing when it did it during game play vs. attract?

#4 1 year ago

Yup, same steady pulsing each of the three times I heard the sound.

No new information. I've been playing the game quite a bit over the last few weeks without indecent. And on several occasions I've set the drop targets and let the game sit in attract for a few hours. Each time I check back, the targets remain up.

#5 1 year ago

Doesn't the 4 white roll over buttons on the top of the playfield cause that drop targets to drop too?? Maybe one of those switched need adjustment. Just guessing on that.


#6 1 year ago

Thanks for the replies...

I have messed around with the little white buttons, but I don't think that's the problem. For example, hitting the #1 button may drop the #1 target, but then that button is out of play until the bank resets. Likewise the buttons aren't in play during attract.

#7 1 year ago

First thing I'd do is start looking at caps and diodes related to the target matrix. There really isn't enough information to give any specific suggestions. The closest I've seen is the phantom pop bumper kicks that would happen randomly sometimes that replacing caps fixed.

The one thing that might point to something else is the attract pulsing you mention. If it is a specific time matching the lamp and music pulse...it could be related to that, but not really sure what exactly that would point to. Is it only a click - or is it buzzing?

#8 1 year ago

It's a click. No buzzing.

#9 1 year ago

Have you tried a different SDB? Maybe try unplugging J4 on the MPU and see if the problem continues.

#10 1 year ago

I don't have a spare driver board. I like the J4 idea. Given the periodic nature of the pulse, I'm thinking data. So pulling J4 could shed some light on that. Can the connector be pulled with the game powered on? I can't really do any experimenting until (if ever) the behavior reappears. Maybe a better idea would be to poke around the driver board's decoder with a logic probe.

#11 1 year ago

Probe the decoder and the 3081 for the drop coils.

#12 1 year ago

Since it’s doing the same timed clicking during play as in attract (when it happens) then doesn’t sound like related to the various lamps flashing during attract. I’ve pulled J4 before and the worst that happens is a coil or two might fire off once as I remove it but that was all.

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