Comet pinball slingshot not working

check the connectors,anything burnt?, shorted wire? switch not making good contact?, coil have a broken wire.........
 
Switch is working fine, and the slingshot itself was working fine until yesterday. Switch reads almost 5v between the contacts it just seems the coil isn't getting any juice when the switch is closed.
 
Read the section non-working coils of the pinrepair.com sys9/11 guide.

That coil is part of the special solenoid section - not cpu controlled.

Check the ohms of the coil to see if it has a broken winding.

Check power at the coil by putting your DMM to dc volts. Put the black lead on the ground strip of the cabinet and put the red lead on each coil lug. Should be the same volts on each side.

If power is good, find the appropriate TIP122/102 on the cpu board. Connect an alligator clip to the ground strap in the backbox, and briefly touch the other lead to the tab of the TIP. If the coil fires, the problem is on the CPU. If not, you have a wiring issue (of course, the previous test would have already found this).
 
Read the section non-working coils of the pinrepair.com sys9/11 guide.

That coil is part of the special solenoid section - not cpu controlled.

Check the ohms of the coil to see if it has a broken winding.

Check power at the coil by putting your DMM to dc volts. Put the black lead on the ground strip of the cabinet and put the red lead on each coil lug. Should be the same volts on each side.

If power is good, find the appropriate TIP122/102 on the cpu board. Connect an alligator clip to the ground strap in the backbox, and briefly touch the other lead to the tab of the TIP. If the coil fires, the problem is on the CPU. If not, you have a wiring issue (of course, the previous test would have already found this).

That's basically what I would do too but I would ground the tab of the driver transistor first. It's the easiest and I'm lazy.
 
Read the section non-working coils of the pinrepair.com sys9/11 guide.

That coil is part of the special solenoid section - not cpu controlled.

Check the ohms of the coil to see if it has a broken winding.

Check power at the coil by putting your DMM to dc volts. Put the black lead on the ground strip of the cabinet and put the red lead on each coil lug. Should be the same volts on each side.

If power is good, find the appropriate TIP122/102 on the cpu board. Connect an alligator clip to the ground strap in the backbox, and briefly touch the other lead to the tab of the TIP. If the coil fires, the problem is on the CPU. If not, you have a wiring issue (of course, the previous test would have already found this).




plus 1.......he says it so easy
 
Okay, checked the TIP's and they are not shorted. Can't really test the voltage though as the fuse for the special solenoid keeps blowing. As soon as the cabinet is powered up the special solenoids are engaged and the fuse blows. All of the special solenoids are engaged with the exception of the non-working slingshot. Any clues?
 
Check the coil diodes. Sounds like you have a short in the wiring.
Thanks, I was thinking the same thing but don't have any experience working on pins so I wasn't too sure of where to start. I think I'll probably replace the diodes on all of the coils to start.
 
Have you checked the coils for shorts?
I had a question about this as well. I've been testing the coils by placing my test leads on the lug eyelets. Testing this way, none of them had read as shorted or with resistance lower than 4 ohms. Is this about right?
 
As soon as the cabinet is powered up the special solenoids are engaged and the fuse blows. All of the special solenoids are engaged with the exception of the non-working slingshot. Any clues?

A shorted coil wouldn't cause the coils to energize when you power on the game. I assume that's what you're saying here?

A 7402 IC could be shorted internally if the transistors are being energized when you turn the game on. Either that or a bunch of the special solenoid switches are stuck closed. Or all the driver or pre-driver transistors are shorted.
 
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A shorted coil wouldn't cause the coils to energize when you power on the game. I assume that's what you're saying here?
No, I would expect a shorted coil not to work. I was thinking something would have been shorted period for the coils to energize. I was just replying to Shardian's question on whether or not I tested the coils.

A 7402 IC could be shorted internally if the transistors are being energized when you turn the game on. Either that or a bunch of the special solenoid switches are stuck closed. Or all the driver or pre-driver transistors are shorted.
I checked the switches on the solenoids that are being energized and they do not test as shorted/closed. I also didn't think this was the problem since the slingshot and pop bumpers are so far from each other on the playfield it didn't make sense.

Since Shardian mentioned the coil diodes might be shorted I was going to start by replacing all of the diodes on the coils since the repair guide states it's best to replace them. I tested the TIP122 transistors and they didn't read as shorted. I ordered replacement TIP102 transistors as well as the pre-driver transistors though I haven't replaced any. Should I check the 7402's for shorts? If so, what pins do I need to check?
 
Diode check on DMM, lead on leg 8 (ground), then touch all of the input/output legs. If any are shorted, the chip is bad. I can't remember if you put black or red on the ground pin. Refer to the chip schematic (search online for datasheet) to know which legs are which.

IIRC, the special solenoids have a daisy chained power supply. If you have a bad diode, you basically get a ground short and the lock on/blown fuse effect. Ask me how I learned this...:rolleyes:
 
No, I would expect a shorted coil not to work. I was thinking something would have been shorted period for the coils to energize. I was just replying to Shardian's question on whether or not I tested the coils.

What I was asking is if the coils energize when you power the game on. As in... you turn the game on and the coils energize then blow the fuse. Is that what's happening? If so you can stop wasting your time checking coils and coil diodes. If not... carry on :)

That seems to be what you're saying here. I wasn't saying that you were saying a shorted coil or diode would cause that. It won't.

As soon as the cabinet is powered up the special solenoids are engaged and the fuse blows.

Like I said... bad 7402 or a bunch of shorted pre-drivers, drivers or stuck switches.

EDIT: I would pull the connectors coming from the special solenoid switches and the connector going out to the coils. If you've still got continuity to ground on the tabs of the driver transistors you know they're stuck on for one of the reasons I mentioned above.
 
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You're right. All of the solenoids in the game should be "daisy chained" together.

Yes, and if somewhere in the line you have a shot diode and the power tied to ground, it will effectively short out all of the transistors because power will be flowing on the gang ground trace on the board. But like you said, the transistors would all be testing shorted. It doesn't mean all of the transistors are actually bad though. The one directly tied to the short will be. If the fuse is over rated though... I pity the foo with that board.

Re-test all of the transistors. You probably did it wrong. If any test bad, take them out and test them again. If you find a bad transistor, you have to check everything in that circuit.
 
Yes, and if somewhere in the line you have a shot diode and the power tied to ground, it will effectively short out all of the transistors because power will be flowing on the gang ground trace on the board.

The only path to ground should be through the driver transistor. I'm not sure what you mean by "power tied to ground". Even with a shorted coil diode there should be no path to ground anywhere until a driver transistor is biased (or shorted). The diodes on the coils are there to absorb the reverse voltage spike on coil colapse. Unless I'm missing something?

EDIT: We are talking about coil diodes here, right?
 
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The only path to ground should be through the driver transistor. I'm not sure what you mean by "power tied to ground". Even with a shorted coil diode there should be no path to ground anywhere until a driver transistor is biased (or shorted). The diodes on the coils are there to absorb the reverse voltage spike on coil colapse. Unless I'm missing something?

I've installed wires onto a coil with the wires reversed on the diode because the new coil had the diode on opposite of the old one. This was the resulting symptoms. It was a pain.
 
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