heres the start up sequence for pre 1975 single player Gottlieb games - in particular PRO FOOTBALL
INSERT COIN OR PUSH CREDIT BUTTON ACTIVATES "S" RELAY
S RELAY ENERGISES "HOLD" RELAY AND ILLUMINATES GAME
S RELAY STARTS MOTOR RUNNING
SB RELAY IS ACTIVATED THROUGH SCORE MOTOR
SB RELAY ENERGISES "Z" RELAY
Z RELAY RESETS PLAYER 1 SCORE REEL TO ZERO
SB RELAY RESETS PLAYER UNIT THROUGH SCORE MOTOR
U RELAY RESETS RESET BANK AND DROP TARGETS
IF BALL IN OUTHOLE THEN "O" RELAY ACTIVATED THROUGH SCORE MOTOR AND SWITCH ON XB RELAY
O RELAY WILL NOT WORK IF 'BONUS UNIT"IS NOT AT ZERO.
Ok, i dont have a GTb game of this vintage so ill be using my 1964 Williams instead. What we need to asacertain is that the switches are open and closed properly -= this is the only logic there is in an EM game, its either on or off ( logic 1 or 0)
I find an ANOLOGUE multi meter is best for this because we dont have to read numbers on a display to verify switch closure - we just need to see needle sweep.
First of all - set meter to LOW OHMS setting
an OPEN switch looks like this on the meter - needle is all the way to the left
CLOSED switch looks like this
Now lets say we have a problem with the XB relay... it will look like this
If you look closely, you can see that some switches in their natural state are meant to be open, some are closed. We need to make sure that a good connection is made by those that are meant to be closed, so we put the leads of our meter across each switch - im using a clip here for one lead as i need my other hand to take the pic - LOL!
If the switch is closed then you should see the needle move over to the right on the display on the multi meter
When the relay is activated, the coil pulls the switches over, this is normally a pulse, but some are held in place ie - HOLD relay. This will change some switches from OPEN to CLOSED etc To check this state just move the switch stack over with your finger, use a clip and test each switch one by one
If testing a switch closure on the score motor attach clips to the switch in question making sure they are not touching each other or anything else and turn the motor by hand - you should see the needle move over as the switch gets closed - if not - IT IS FAULTY
Be careful when attaching the clips - follow the leaf switch through, its easy to get confused with what solder joint is connected to what switch.
If you follow this procedure through from start of sequence to the end systematically then there is no reason why you cant either diagnose why the game wont start, or get it started.
If the score motor is running, then its is safe to assume the S relay is activating motor and we can move onto the SB relay stage etc
