(Topic ID: 173640)

WPC locked on coil

By grbgemen

5 years ago

Topic Stats

  • 3 posts
  • 3 Pinsiders participating
  • Latest reply 9 months ago by ALY
  • Topic is favorited by 1 Pinsider


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#1 5 years ago

Working on a basket case Party Zone.

Issue is on the driver board. Game tested with known good board and coil works fine.

Problem: Locked on coil. DJ kickout. Manual says Q76 which is a TIP36c.

I have replaced:

Q76 TIP36c
Q75 TIP102
Q73 2N5401
D29 1N4004

Other resistors associated with this solenoid were tested and within range.

After replacing above, coil still locked on...

From my research, next inline is U5 74LS374. Cut out old U5 and put in socket(buzzed out all my traces). New 74LS374 installed and coil still locked on.

All three transistors still test good. Even pulled from board and tested.

Any advice?


#2 5 years ago

I'm sure you know all of this but I'll say it in case.............

I would remove the coil wire from the connector on the driver board for further testing (or disconnect the coil in some way).

There is only one way the coil can activate. One side of it is always at supply potential (50~80V) and the other side is wired back to the driver board and taken to ground when the coil is to fire.

I would then turn on the machine and start taking measurements back through the circuit until I located where the signal ISN'T activating the driver circuitry (all the bits you replaced).

I would also look closely around J113 etc (whichever applies to your problem area) for shorts or perhaps a ribbon cable incorrectly seated or off by one pin?

This is a lot easier than just replacing parts and crossing fingers. A meter and taking voltage measurements is essential in this case.

ScreenHunter_174 Nov. 16 10.44 (resized).jpg

4 years later
#3 9 months ago

Sorry for bringing up the old topic, but it's a problem that will never get old

I also have a similar issue with continuous power on one solenoid (center pop bumber) which basically started frying before any of the fuses went out. It's actually linked with Low power solenoid circuil, F104 with +60V on one coil side.
I unsoldered the GND wire from the solenoid, powered up the machine and the power on the coil is constant +60V + GND. Even if I unplug the cpu board from the power board, still the same.
Q46 and the diode are good - measured with multimeter.
The cpu board had some corrosion and the Escape button appears to be pressed by U16 even if the switches connector J205 is unplugged. Could it be that the corrosion caused the solenoid to fire up constantly? But why would it be locked even when the cpu is unplugged.

Any clues?

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