Quoted from Pin_Guy:Q53 (2N5401) is a PNP transistor, it requires a low on its base to turn on.
Pin_Guy is correct. I was going from memory and thinking it was a NPN. This is what happens when you get senile, Sorry about that.
Quoted from SPARKY70:Also which legs should be hi/lo on the Q54 driver?
The base (pin 1) will low when off and high when turned on.
Quoted from SPARKY70:Can you please tell me which leg to test for the lo coming into the Q53 pre driver, and which leg to test for the hi coming out? Is it safe to test all 3?
The base (pin 2) is the lead that turns it on and off, high off low on.
The collector (pin 3) is the output the turns on the driver (TIP 102). A high on the collector means the transistor is conducting or a on state which will turn on the driver transistor. The emitter (pin1) will just have 5 volts on it all the time.
It is safe to test all 3 for the predriver, the collector of the TIP102 will have high voltage on it and should not be tested with a logic probe. It can be tested with your voltmeter.
Quoted from SPARKY70:I am guessing that i could put my probe on J127 &129 to check if it is lo or hi if i am safe to do so.
You diode tested the predriver and it tested good but is most likely bad causing the driver to stay on. The best testing is done with the power on with the logic probe, in attract mode the base of Q-53 should be high and the collector should be low. If the base is high and the collector is high the then Q-53 is bad. If the predriver tests good then you may have gotten a bad TIP102, it happens.