Arcade Collecting > Pinball
System 11 Stuck Coil, Please help.
Santoro:
The lower pop bumper on my Space Station is stuck on. Following the guides (http://www.pinrepair.com/sys11/index2.htm) I replaced the coil, two transistors, and the two ICs behind them to no avail. It still goes down as soon as the pin is powered on.
I am running out of ideas. How can I troubleshoot this the next step?
I took the offending coil out of the circuit and the other two bumpers work fine so I think I did a good job on the component replacements. Could this be a switch problem? Power?
The bumper first got stuck when I (very noobishly) tried to adjust the leaf switch one time while the machine was on. I shorted something out and the rest is history.
smartbomb2084:
So... You replaced the coil, Q79, Q78, U50, and U49?
Santoro:
I replaced the coil, Q78, Q79, U50 and U51. I also replaced C74 (just in case) and R108 (it didn't test out at the right resistance.)
You thnk I should have replaced U49, and not the U51 PIO? Maybe I replaced the wrong IC in error? I don't think so, but you never know.
Santoro:
reading it again and look at that:
--- Quote ---Special Solenoid Logic Flow.
For Special Solenoids (SSa to SSf), here is the logic flow. This is useful to know if you are having a problem with a special solenoid.
SSx: 6821 PIA 7407 7402 2N4401 TIP122
---------------------------------------------------
...
....
....
....
....
SSf: U54 (pin 39) to U49 to U50 to Q78 to Q79
--- End quote ---
Off to replace U49. Thanks for the lead.
lilshawn:
remember... all the solenoids have power 100% of the time...what happens when it comes time to fire them is the circuit to ground is completed...
the first thing the computer sees is the switch for the popper close... go to the switch test and see if it's stuck on and that it does indeed operate properly. if it is fine, the next thing that happens is the computer ends a signal to a chip which in turn switches on a transistor, that switches another larger transistor which completes the power loop from the solenoid to ground. since you've replaced the chip and transistors I would look for a wire thats grounded or pinched to the frame someplace.
you can check by disconnecting the offending solenoids return wire from the board. what this will do is isolate the power wire and the coil and it's return... if it is indeed shorted someplace along the return the solenoid will still come on. if it does not, perhaps you have replaced the wrong transistor... i've done it before. :P :laugh:
EDIT: read the new posts... :banghead: i'm too long winded
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