(Topic ID: 242656)

Johnny Mnemonic - problem with the hand


By jimy_speedt

6 months ago



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  • 32 posts
  • 8 Pinsiders participating
  • Latest reply 5 months ago by jimy_speedt
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#1 6 months ago

Hi,

I purchased a beautiful JM but unfortunately, the hand has a few problems.

- First of all, it regularly displays errors at machine switching. X and Y home position of the hand.
- Then, sometimes when capturing the ball for a lane shooting (not the oxo), the hand stays at it position and release the ball at the initial position, it tries a few times, then it ends up moving and dropping the ball properly.
- When moving the hand to the oxo, it happens that pressing the button up or down does not work. Also it sometimes drops the ball without action from me, and timeout is not reached.

If someone could advise about what I could start checking, it would be great.

Thanks

#2 6 months ago

Time for a rebuild. Take the whole back frame with hand assembly off and remove and clean all parts and put back together. Sounds like the home switches for x and y or the opto wheels need some attention. Look through the JM owners thread it outlines this whole process.

#3 6 months ago

Hi,

I am about to do it. What key would you use to unscrew the opto wheel ?

Thank you

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#4 6 months ago

Allen key, careful when putting it back on because if you over tighten it you will crack the plastic or unseat the brass bushing

#5 6 months ago

Also, make sure the center drop target up/down switch is working. If that switch is not registering correctly the MPU dosen't know how to correctly handle the glove operation (the lack of movement and random dropping you described sounds like you may have issue)

#6 6 months ago

but the "golden" circle, how do I remove it ?

#7 6 months ago
Quoted from jimy_speedt:

but the "golden" circle, how do I remove it ?

Don’t remove that, the Allen set screw just needs to be loosed a bit so you can slide off the opto wheel

#8 6 months ago

I have received today the set of hex keys US size. This little stuff is not strong enough to unlock the screw. It ends up going loose in the screw

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#9 6 months ago

I'd recommend getting a set of 1/4 Allen bits, or a set of T-handle drivers.
As far as the slipping goes, sometimes these machines have a mix of standard AND Metric nuts and bolts, especially if it has been repaired by many people over many years.

allan (resized).jpgthandle (resized).jpg
#10 6 months ago

I thought the hex key size is 1/16?

#11 6 months ago
Quoted from yuriijos:

I thought the hex key size is 1/16?

I believe that's what it's supposed to be, but I've found some weird things in machines over the years, I've personally found a set screw that had the same threading and outer diameter but the hex was metric and larger than the manual stated it should be, so this could be the case for OP as well.

#12 6 months ago

The set I purchased contains both metric and US sizes.

#13 6 months ago

I have cleaned the optos, reseated the connectors, de-greased the x and Y axis, put fine oil on them. It seems to work fine. Hopefully for some time thanks for the support

#14 6 months ago

I have been a bit too early when I said "solved".

I could play normally 10 games, then the glove went to a wrong position, preventing the ball from the VUK to reach the glove center. The ball hurts the side and fall back to the VUK. However, I have no longer messages saying X or Y home position failing. Only "Check F5". And it is always when the ball is supposed to be dropped a bit below on the playfield than the problem occurs.

Also, while moving the ball from the left to the OXO, suddenly, the ball is dropped onto a cell without action from me, not while on the playfield, but on the OXO. Then the glove stops and I cannot make it move with the buttons, it stays above the ball. After a little while, the Oxo ejection metallic frame tries to release the ball, but is unable to do it as it is blocked by the glove.

So the mechanism works, but there is something weird that mess up the glove location and ball drop. Sorry, I am repeating what I have written above, but this is the situation of today.

I am still stuck again. Thanks for giving me some directions to try.

#15 6 months ago
Quoted from jimy_speedt:

I have been a bit too early when I said "solved".
I could play normally 10 games, then the glove went into a …...frenzy??

same with me . new ball in hand switch , new nuts y switch , backboard wiring , fully resoldered boards ,and-still , wont drop ball , goes to matrix without ball , all sorts of weird things . friend coming to help me tonite-morrow .let you know what we find

#16 6 months ago

Check your wires to the magnet and replace if necessary.

#17 6 months ago
Quoted from insx:

Check your wires to the magnet and replace if necessary.

have already .back on it tomorrow

#18 6 months ago

I made the full check of the hand, in hand test mode, after re-cleaning the optos and it worked perfectly. I had a look to the wiring and it looks almost new, no damage. I removed the dual relay board on which I have not found abnormal measurements.

Restarted a game : successful. But at the second one, the hand dropped the third ball on the oxo and stopped working, no reaction to any button pressing.

Can the cause come from the driver or should I focus on the board and wiring ? Also knowing that the ball release before timeout is not managed by the hand movement mechanism.

Thank you very much

#19 6 months ago

The only time I've seen this happen is when the game thinks the ball is in the glove when it shouldn't be.
When the grid is lit the center drop target "down" switch tells the game that a ball in the popper should go to the glove and that the glove should do stuff.
If a ball gets in there and the switch is flaky/dead the game thinks the ball should be on the play field and kills the glove and drops the ball.
My guess is that you may have a loose connection on the switch (#43-Drop target in the manual) which makes it work sometimes.

#20 6 months ago
Quoted from buffaloatx:

The only time I've seen this happen is when the game thinks the ball is in the glove when it shouldn't be.
When the grid is lit the center drop target "down" switch tells the game that a ball in the popper should go to the glove and that the glove should do stuff.
If a ball gets in there and the switch is flaky/dead the game thinks the ball should be on the play field and kills the glove and drops the ball.
My guess is that you may have a loose connection on the switch (#43-Drop target in the manual) which makes it work sometimes.

Thanks for the answer. Only the display says I must move the hand to the oxo, not complete a white arrow objective on the playfield. Bizarre

#21 6 months ago
Quoted from jimy_speedt:

Thanks for the answer. Only the display says I must move the hand to the oxo, not complete a white arrow objective on the playfield. Bizarre

Sorry if I was unclear, but I meant lighting locks, not white arrow objectives. The drop target protects the entrance to the ball popper that kicks the ball to the glove. If the game thinks the drop target is still up it will kill the glove after a second or two thinking the ball bounced into the popper. As far as I can remember there is no other way to get the ball out of the popper without the glove grabbing it and dropping it back on the play field, and the glove dosen't have any other functions besides locking balls in the tic-tac-toe board.

#22 6 months ago

yes oxo is tic tac toe
thanks for the clarification. It takes about 5-6 seconds to bring the hand above the TTT panel, does it match with your experience ?

#23 6 months ago

There is a JM hand magnet service bulletin. Make sure that is done. And replace the x,y nuts. If they slip, because of age and wear it will cause errors. And it won't find the proper x,y positions.

#24 6 months ago

Yes, it does.

#25 5 months ago

I have ordered the whole wiring harness, and the magnet switch. just to see whether it solves things. I cannot figure out why a mechanism that recognizes the home switches, that go left to right, in and out, and the other way around would fail. Who is the $§@@!% father of this messy pinball ?

#26 5 months ago
Quoted from jimy_speedt:

I have ordered the whole wiring harness, and the magnet switch. just to see whether it solves things. I cannot figure out why a mechanism that recognizes the home switches, that go left to right, in and out, and the other way around would fail. What is the $§@@!% father of this messy pinball ?</blockquote after going thru everything like yourself , we pushed restore factory settings . no problem since …….try that . I will keep you posted on how mine goes

1 week later
#27 5 months ago

20 games in and no signs of failure

#28 5 months ago

Sorry I had not seen your comment as it was incorporated in the OP message. I will do

#29 5 months ago
Quoted from jimy_speedt:

I have ordered the whole wiring harness

Where did you order this from. I cant find it anywhere.

#30 5 months ago
Quoted from Mitch:

Where did you order this from. I cant find it anywhere.

This is it, but I guess I ordered the last one. Hopefully it will be in the box I ll receive

https://www.marcospecialties.com/pinball-parts/H-20469.3

#31 5 months ago
Quoted from jimy_speedt:

I have ordered the whole wiring harness, and the magnet switch. just to see whether it solves things. I cannot figure out why a mechanism that recognizes the home switches, that go left to right, in and out, and the other way around would fail. Who is the $§@@!% father of this messy pinball ?

It will fail because it knows the motor is rotating but it's taking too long to get to the home positions. Because the nuts are slipping on the worm gear. It may seem like it's ok. But if the limit switches are working. The problem is 100% the x,y nuts. Don't mess around, replace them.

#32 5 months ago

I will do all of this , thanks

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