(Topic ID: 56144)

Bumper and slingshot problems *happened again*


By sed6

6 years ago



Topic Stats

  • 60 posts
  • 10 Pinsiders participating
  • Latest reply 6 years ago by Fanatic
  • Topic is favorited by 3 Pinsiders

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switch_matrix_space_invaders.pdf (PDF preview)

There are 60 posts in this topic. You are on page 2 of 2.
#51 6 years ago

I've been following this discussion since I was having a similar problem with the pop-bumper or thumper bumper on my game.

What I found which fixed the problem:
The solder joints on the upper-right flipper coil were defective.
The diodes (2) had both come free from the circuit and were making intermittent vibratory contact.
This was the result of a previous "repair" done poorly.
Easy fix. I'm hoping this is where your intermittent problem could lie.
Maybe take a look at these connections at all of your coils? Inspect for dull/sloppy/cracked joints.

The reason I write this is because problems rarely "fix" themselves. They just get worse over time and turn into a more serious repair issue down the line.

#52 6 years ago

Agreed 100%! I do want to find the source of the problem and I'll check my solder connections and diodes too. Problem is now that is running all I want to do is play it! I had a buddy come over to tonight and he hasn't played pins in years but he beat me about 5/10 games. Sheeze.

#53 6 years ago

So it happened again. Same symptoms. With one addition, if you hold the button the left lower flipper now bounces back and forth and won't stay up. I was soldering underneath and shorted a GI light socket to one of my flipper wires. Any idea what I did there?

So back to my main problem. I used my new logic probe and checked pins 20-23 of U2 on the SD. 20-22 went high then low depending on what solenoid was firing. Pin 23 stayed high I believe. It blinked off a time or two during the noid test, but never lit the low light. Per Andrews direction I then tested continuity from U11 on the MPU to U2 on the SD. They all check fine with no breaks in continuity. Here's a pic of my notes. Any tips from here?

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#54 6 years ago

If it is constantly high and never goes low there is a problem on that line. It should be mostly high with low spikes (when selected). If you can trace continuity all the way back to the PIA on the MPU and there is no breaks that leaves the PIA or some kind of short. Could still be a lack of continuity, just the pressure from the your DMM leads is making the connection.

I wouldnt think a PIA fault could be intermittant, but maybe... also shorts are rarely intermittant as well. Try swapping the two PIAs at u10 and u11. Maybe the PIA socket is flakey.

You now know where to thorougly check though.

#55 6 years ago

I find myself still chasing my own problem too. The thumper still occasionally gives a hick-up in relation to the flipper buttons...........strange that our problems are similar.

This past weekend - the thumper quit working entirely.
After an afternoon studying the board and checking the resistors, transistors, etc.....
I found the problem in the "ground" or return line which is common to a number of items. The way I found it was by physically chasing the "suspect" wire throughout the wiring harness to the point of fault. Took a lot less time than it sounds like.

Perhaps you have a solder blob shorting the wiring harness?? This thought is what led me to follow the wiring harness carefully. I was not being cautious while making other repairs under the playfield and had a splat or two.

The targets on my game share a common ground with the coils - flippers, gate, drop-target, etc.
Ground wiring had come loose and the wires had separated thereby opening the circuit. Why all of these items were not effected is beyond me. Some things still worked??
I'm considering just re-doing the entire string in sections as time allows. Grab the schematic and go point-to-point re-soldering connections and replacing the small caps and diodes at each target, coil, switch, etc. Simple work - cheap cost - time well spent IMO.

Edited to say: The thumper still gives the occasional hick-up during game play.
I will continue to follow this discussion to see if you turn anything up.

#56 6 years ago

Fanatic,

SED6's issue is on the encoded side of the solenoid signals. Sounds like your issues was past the decoder.

The the bumpers firing with slings is normal to a point in a classic bally and unavoidable. Things to help isolate flipper noise getting into the switch matrix is to have clean end of stroke and flipper button contacts. The bigger the spark, the more noise there seams to be. Sometimes the ceramic disk capacitors on the switch matrix switch can go bad as well.

#57 6 years ago

Fanatic mentioned a ground problem which reminds me of something I forgot to mention. When I was adjusting the leaf switch gaps on my flippers with the game turned on, I could feel the voltage when I touched the leaf switch with my allen tool (cut with a slot to adjust blades) in one hand and my other hand on the metal side rail. When I removed my hand from the side rail the current went away. Is this normal? Doesn't seem like it should be.

#58 6 years ago

Make sure game is grounded properly. The side rails and all metal should be connected to the earth ground.

Switches run at 5v and low current. I doubt you could feel it. Solenoid voltage will make you jump. Display high voltage will light you up.

Best practice is to not adjust switches with power on.

#59 6 years ago

I do appreciate the input guys! I swapped U11 and U10 and the problem resolved itself. Again. For now. It was probably a result of reseating the chips more than swapping them I guess. I will continue to hunt for suspect solder connections. Right now I'm off to find a fix for the bouncing flipper. Here's a vid of my LEDs so far.

#60 6 years ago
Quoted from barakandl:

Fanatic,
SED6's issue is on the encoded side of the solenoid signals. Sounds like your issues was past the decoder.
The the bumpers firing with slings is normal to a point in a classic bally and unavoidable. Things to help isolate flipper noise getting into the switch matrix is to have clean end of stroke and flipper button contacts. The bigger the spark, the more noise there seams to be. Sometimes the ceramic disk capacitors on the switch matrix switch can go bad as well.

Yes, you're correct. Decoder was fine in my case.
Excellent suggestion with checking the EOS switches - very good observation.
I was wondering if the "back EMF" from the coils could make it onto the control signal cct. You've confirmed my suspicion as valid. Thanks big time.

SED6 - Please keep updating as you make further progress.

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