Apr 172016
 

Got this game for a repair.

Game booted without problems but it was missing music and sound effects.

The amplifier was working correctly as I could hear the typical white noise coming out of the speakers.

Shoot2

 

Shoot3

 

As you can see, the game is upside down and checking with Mame there is no flip dipswitch so unfortunately is one of the few horizontal arcade games which has the screen upside down (the other that I know is Athena from SNK).

Another thing you should have noticed is the copyright…..some smart italian arcade owner has hacked the original date from 1985 to 1987 to make the game looking newer….it’s unfortunately very common in Italy.

back to the real problem, I checked with my portable amplifier the input to the operational amplifier and there was no sound.

That meant that either the DAC was faulty of something in the sound circuit logic.

The DAC is a YM3014

YM3014

The SD pin is the output of the YM2203 which is a digital waveform so normally you cannot check with an amp if the YM2203 is working or not.

The only thing you can hear is white noise but there is a trick:  compare the breaks between melodies (example, between coin up and start game), so the YM2203 should also stop orstart again to output signals.

With this trick I could confirm that the DAC was faulty.

Replacing the YM3014 with a good one fixed the problem as expected.

Shootout