Quoted from Quench:

Ok, maybe doing these tests in lamp test mode wasn't a good idea since it doesn't help your multi-meter to give steady readings.
Please open up a support thread for this in the "Tech: Early solid State" subforum so this thread can return to normal discussion about the games.
Try the following and answer in your new thread.
Install normal incandescents in the Tilt lamp socket and also the Ball In Play lamp sockets.
Start a game and put it in Tilt mode.
Measure the voltages on the lamp driver board at the following locations (black multi-meter lead connected to TP1 GND on the lamp driver board and leave it there).
Measure these locations for the Tilt lamp:
U4 Pin 14
U8 Pin 14
U8 Pin 15
Q47 gate leg
Measure these locations for the Ball in Play lamps:
U1 Pin 14
U6 Pin 11
U6 Pin 12
Q16 gate leg

Both these lamps should be lit so we're comparing voltages for their selection and drive circuits.

The following images are to clarify IC pin leg numbering anti-clockwise:

[quoted image]
[quoted image]

Quoted from Quench:

- The cathode (left) leg of the Q47 SCR to the cathode of any other SCR (all cathodes are connected together to ground).