Later games using the -51 sound board have software that waits for the MPU PIA's test or possibly attract mode to hit before they become active.

ie... in gold ball or other later -51 sound games if you push the sound board test button before the MPU fully boots up it makes the sound board lock up until it is power cycled. Silverball mania doesnt act like that tho, you can push the sound diag button as soon as power is applied and it will make test noise.

That being said if you put a late model software into an older game using the -51 sound board, it may appear dead. When testing these boards I usually use SBM software as I am familiar with the sound board decoding pattern and how it should sound.

Break the sound board into three sections.

The CPU stuff
The sound input stuff
The sound amplification

For the CPU, diag it like any 6802 computer. You need a clock pulse (External clock cpu p37). High reset (p40, DO NOT FORCE RESET HIGH if low YOU WILL BLOW UP THE 4011 chip). If the eprom /CE is pulsing and the CPU is doing work let the game mpu boot up all the way (or use SBM or other old software). Push the diag button and monitor TP4. When sound is playing TP4 (i think it is VMA) will start pulsing. If that looks good continue

For sound input stuff put the game in sound test and monitor the sound signals coming in the sound, inverting through the 4049, and then to the sound chip. If they all make it to the sound chip keep going. The sound chip can fail and not decode sound patterns properly, so keep that in mind.

For amplification problems introduce noise with your finger on a probe. If you get low, but adjustable volume the preamp is usually the cause. Zero sound and the CPU is running and the sound inputs look good, try the main amp.

The Bally 560-3 repair manual is very good for this board and way more detailed than what i typed out. IF you can follow the Bally 560-3 book, you can fix your board.
http://arcarc.xmission.com/Pinball/PDF%20Pinball%20Misc/Pin%20Repair.pdf

around page 77 in that PDF file.