DE cpu board problem

[paddythegreek]

Just installed a spare cpu board in Maverick (more to test the board than run it) and i got the ball launch coil locking on. The coil appears ok. I've replaced the tip102,the 2n4401 pre drive and the 7408 chip and still the damn things locking on. There are 2 resistor networks in the circuit and they both read ok as does the 68 ohm resistor.
Using my dmm in diode mode i get a reading when touching the red lead to the center pin and the black lead to both outer pins of tip 102. The other transistors read nothing (OL)
Any ideas anyone

 

[paddythegreek]

Ok something is grounding the tip transistor. There are NO loose bits of solder or solder splashes touching things they shouldn't. Is it possible the switch pia has a fault thats causing this cos i'm running out of ideas.

 

[PinballDaze]

Seems a common problem with Data East.
Sorry, but don't know the solution.
No much help really, but having a bad day