Probably all the electrolytic capacitors should be replaced.

if it turns out to be a sound prom , i have them. i would try new caps first , usually its a thud thud thud sound if the prom is bad.

Yep, those old, dried-out caps are usually the first place to look.

The -32 and -50 boards have an absurdly high failure rate in the ICs. From the PROM to the 4042s, to the weird obsolete 8439, etc. It must be a terrible design. Replacing the caps is a start, but not the cause of issues typically on this sound board.

This board is a bit of a pain to trouble shoot. It is best to have a scope or logic probe at least and work through oliver okeigi's write up.

Bad PROM is usually identified bad no pulsing on data out 2 - PIN2 of the prom (i think it is that pin) or every note the sound board plays is the same pitch.

http://www.pinball4you.ch/okaegi/rep_soundold.html

Diagnostic from this point involves putting the game in sound test and watching how everything works. Start at the clock/timer/prom area then work towards the amplifiers. Okaegi's write up should get you fixed if you can follow it.

Oh. The title of the thread made me think it is the orginal lost world.

I just picked an eftlw and am having the same sound issues. Sounds like caps did not solve the prob. Hoping to see what the solution is

I replaced my 2 main caps on my soundboard and the sound is much much better. There still is a static background sound though so I think it could be fixed or improved just not sure what the next step is. Do I replace something else on the sound board?