Basic HTML Version
•
•
•
-,
•
[ ] 9.Start the test by pressing the CREDIT button. If coils
operate correctly, the game is ready for play. If they don't,
turn the game off and contact your authorized Bally dis-
tributor .
REMEDIES FOR "TOUGH DOG" COIL PROBLEMS
INTRODUCTION
Your coil driver circuit contains a zero crossing detector.
The game depends on this detector to time firing pulses for
game-controlled coils. Controlled coils energize for three to
four zero crossings (25 ms).
SYMPTOM: COIL ALWAYS OFF
Connect one end of a jumper to ground (or TP2).
Tap
the
jumper's free end on the metal tab of the inoperative coil's
driver transistor.
(This transistor
has a
TO-220, power tab
case.
The tab is connected to the transistor's collector.)
CAUTION
Never hold a grounding jumper on the tabl More than
momentary contact causes circuit damage. The coil fuse or
even the coil, itself may burn.
NOW COIL PULLS IN. If the coil pulls tn, check the driver
transistor. To check the transistor, jump from TP6 to the
base of the driver transistor.
COIL DOESN'T PULL IN. With its base pulled up to TP6
potential, the transistor should energize the coil. If the coil
doesn't pull in, replace the transistor. If the coil operates,
check the transistor's series diode for an open circuit.
Assuming that you find a good series diode, proceed back-
ward one stage in the circuit. Ground the appropriate
CA3081 transistor base. The coil should operate. But if it
doesn't, replace the CA3081 decoder chip.
Once again, ground the appropriate CA3081 transistor
base. If the coil doesn't energize, jump the bottom of the
4-21