You should be right Stu. The best way to check a TIP102 is to set the MM to "continuity" and then check for any shorts. Testing them this way is the easiest, and when you switch the game on, you won't have any locked on coils caused by the transistors. Measuring resistance to ground will give you different readings as you are measuring the "circuit", not the component. There are other components influencing the reading as the other components can have a 10% tolerance - like resistors for example..
cheers mate. one question re the HV section - the trimmer pot ? - do you use it? what do you trim voltages(?) to ?
The trimpot is used to adjust the high voltage to the displays. I usually drop mine to 170vdc. Grab a MM and set to VDC. Place the black lead on the GND TP and the red lead on TP2. The pot is used to lower the output voltage, so by adjusting it down to 170vdc, you are prolonging the life of the displays. It the HV section has a faulty transistor, you will get full 220vdc to 240vdc on TP2. Not Good.
If adjusting the trimpot does not change the output voltage at TP2, then you need a Bally HV Kit ;
http://www.rtbb.com.au/catalog/product_info.php?cPath=22_128_130&products_id=1127
