Received from USA this Pac-Mania ROM board (Namco System 1 hardware) for repair :

According to the owner board played fine but mute, this was confirmed once powered it up.Using my audio probe I could hear sound on the input (pin 2) of the two LA4460 amplifiers but nothing on outputs:

At closer inspection one of them was literally blown up:

So I proceeded to remove both:

and installed two new spares and some thermal compound on heatsink:

Sound restored and board 100% fixed.End of job.

Update:

After converting this board to Splatterhouse I found that voices and other sound FXs were missing:

I quickly pinpointed the fault in a bad TL084 OP-AMP, replacing it cured the issue:

Some days ago I received this faulty Punk Shot PCB (manufactured by Konami in 1990) 

Game had small glitches over the sprites and played mute:

MASK ROMs check reported two bad devices:

Usually jailbars mean some problem in data bus so I went to look at relevant circuit.As in many Konami PCBs the sprites generation circuit is condended in two ASICs : the ‘051960’  which generates the address lines for the MASK ROMs and the ‘051937’ which reads data.Indeed I found a missing connection beetween pin 84 of  the ‘051937’ and pin 28 of the 8Mbit MASK ROM @K7 

This was caused by a broken via on solderside:

Patching it restored graphics, MASK ROMs check successfully performed now:

As for lack of sound I quickly pinpointed the fault in a 2k x 8bit static RAM @E6 (connected to Z80 audio CPU). piggybacking it restored sound.Once removed I had confirm it was really bad :   

Job done.