Strange switch problem

willymotts

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One of the pop bumpers on my Embryon does not work during game play but does function OK in the test. In my fiddling with it, I discovered that if I brush my finger across the leaf or, better yet, a screwdriver that I am holding onto by the metal, the switch will actuate. Just holding my finger or the screwdriver on the leaf does nothing. It must be the swish-contact like when starting an arc on an electric welder. (This does not cause any visible spark.) What gives? Better yet, how do I fix it? Thanks.
 
Alright, thanks for your time. I'll see what I can find. Too bad, though, I was really interested in what might be up with this.
 
Well hey man stay positive, you will figure this out. I mean part of owning these pinball machines is also fixing them too, I'am still learning myself but I have come along way and have fixed stuff myself with the help from people here on this forum. So I say hang in there maybe someone here with lots of experience can be helpful, people like that are not constantly on here 24/7 they have lives and there own games to maintain. Stay positive! Jeff
 
so it sounds like you are grounding the coil,all coils are powered(usally the bigger of the two wires is the power to the coil)the other is ground,if you turn the game on in attract mode,take a jumper wire and run it from your ground strap to the ground on the coil,if it pulls the pop bumper it probabally means one of the TIPS on the solenoid driver is defective,to find which one controls the pop bumper it is just easiest to get the schem. and find which TIP controls it,usually a Q follwed by a #
 
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i looked at the schem. it says,L top pop is Q14,L bottom is Q9,R top is Q10,R bottom is Q12,you can change the tip its very easy to do,i have lots of Tip106,107s,confirm this is your problem,give me your address and i will mail you one.
 
so it sounds like you are grounding the coil,all coils are powered(usally the bigger of the two wires is the power to the coil)the other is ground,if you turn the game on in attract mode,take a jumper wire and run it from your ground strap to the ground on the coil,if it pulls the pop bumper it probabally means one of the TIPS on the solenoid driver is defective,to find which one controls the pop bumper it is just easiest to get the schem. and find which TIP controls it,usually a Q follwed by a #

Your body is unlikely to conduct enough electricity energize a coil in a pinball machine. If it did you would know it because it would be extremely painful. That's not likely what's happening.

Also, he says that the coil works in test mode telling us that the driver transistor is working. Replacing that transistor will not fix the problem.

EDIT: If you did want to manually ground the coils it's best to do it by grounding the metal tab on the driver transistor. That way you're testing the wiring from the driver board to the coil at the same time.
 
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One of the pop bumpers on my Embryon does not work during game play but does function OK in the test. In my fiddling with it, I discovered that if I brush my finger across the leaf or, better yet, a screwdriver that I am holding onto by the metal, the switch will actuate. Just holding my finger or the screwdriver on the leaf does nothing. It must be the swish-contact like when starting an arc on an electric welder. (This does not cause any visible spark.) What gives? Better yet, how do I fix it? Thanks.

I'm not totally sure I understand what you're getting at but I would suspect a switch problem. I would remove the capacitor across that switch and clean/adjust the switch contacts and see what happens. If that fixes it you'll want to install a new capacitor across the switch contacts.
 
Grounding (I tried before posting first) only takes me to "malfunction, malfunction...". I think I may have a diode problem. When I wet my fingers and touch the leaf, it consistently works the coil. I must be "taking" some of the charge meant for the unit and therefore allowing it to work(????) This is all just shooting in the dark here but does this light the bulb in anyone's thinking cap?
 
I think I may have a diode problem.

So check the diode...

When I wet my fingers and touch the leaf, it consistently works the coil. I must be "taking" some of the charge meant for the unit and therefore allowing it to work(????)

You have enough capacitance in your body to make the MPU think the switch is closed when you touch the switch leaf. That's my guess anyway. That's what makes me think you have a problem with the switch contacts, capacitor or diode across the switch.

Make sure your switch is working. To be totally sure I would desolder both sets of wires from the switch and check it with a meter. I've seen switches that looked clean but needed a lot of filing to actually make contact.

This is all just shooting in the dark here but does this light the bulb in anyone's thinking cap?

Yes... I already gave you my advice. I wouldn't waste time worrying about why it works when you lick your finger and touch the switch.
 
So check the diode...



Make sure your switch is working. To be totally sure I would desolder both sets of wires from the switch and check it with a meter. I've seen switches that looked clean but needed a lot of filing to actually make contact.

When working on this vintage of pinball the switch contacts are GOLD plated with just a very thin layer of gold and under that is Silver (Gold is a better conductor then silver but cost so much more they just used a top Layer) when they are cleaned you should never use anything more aggressive then just some thing like a business card, any thing else ( file, sand paper, emery paper, etc.) removes the gold and the switch will need cleaning for the rest of the life of the pin - or replace the switch with another Gold one, good luck with that.
 
Are you on a concrete slab floor....like garage floor or basement slab. From experience, I've had all kinds of crazy stuff happen while working on a slab and touching things on a pinball (of course, I was barefoot at the time).

I was working on a customers Bally Playboy once. Their basement floor was a poured slab...they had big area rugs down. The back half of the Playboy was setting on the actual concrete. At some point I kicked my flip-flops off and was working away. I was finished, and giving all the switches a final check. Sometimes when the ball rolled over a switch or hit a target....all was fine. Other times random coils would (also) fire. I bet I stood there for 20 minutes checking switches....going over the switch matrix....Nothing was adding up. Then it finally hit me. If I wasn't touching the ball when it rolled over/hit a switch....all was good. If I WAS touching the ball while actuating a switch....crazy shit happened. I put my flip-flops back on....problem solved :)

I did have this same issue once on a carpeted first floor....maybe a Power Play or Eight Ball....I know it was an old Bally.

And I'm going to agree with the others...licking your fingers and touching shit is a bad idea.

And I'm going with Lindsey....If it works in test mode, but not in game mode....investigate the switch and it's passives. Could be as simple as a dirty, missing, or mis-adjusted switch contact.

Edward
 
When working on this vintage of pinball the switch contacts are GOLD plated with just a very thin layer of gold and under that is Silver (Gold is a better conductor then silver but cost so much more they just used a top Layer) when they are cleaned you should never use anything more aggressive then just some thing like a business card, any thing else ( file, sand paper, emery paper, etc.) removes the gold and the switch will need cleaning for the rest of the life of the pin - or replace the switch with another Gold one, good luck with that.

Yeah... I've given that same advice at least a dozen times on here. I should have thought twice about using the word "file" but I was thinking of a specific example where I had to file the hell out of a set of contacts.
 
C'mon guys. I wasn't getting ANY shock at all so wetting my fingers only served to confirm that I was acting as a resistor or something. Buncha sissies. (Just kidding.)
UPDATE: I cut off the ceramic capacitor (.47uF) and the coil works fine now. How necessary is that capacitor? I don't want to burn out anything. I got a package of 100 assorted caps at Radio Shack but there is nothing close to the value I need so they're going back. Actionpinball has them for .25 each but the shipping is like $8. That's where I'll get them, though if no one has a better idea. Thanks to all for the help and concern for my health! FYI...I don't have a death wish and I am pretty careful around this stuff.
 
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OK, I know what the cap is for. Without it, the bumper, once started, doesn't want to stop. I have ordered replacement capacitors for this game. Again, thanks to all who helped.
 
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