Some days ago I had on the bench this original Pitfall II PCB:

Board booted but all characters/texts were missing and also sound was totally absent:

I started to check the circuit around the six tiles/characters ROM and found nothing of abormal until I came across a 74LS273 @IC39  with missing clock on pin11:

As you can see from the above picture someone had already socketed it but broken the trace going to pin 11, he tried also to patch this but didn’t make a good work ending up there was no perfect continuity (45 Ohm measured) between this pin and above pad :

Once established  connection, all missing characters were back again:

So I moved to troubleshoot the lack of sound.Putting my fingers on solderside pins of the LA4460 amplfifier didn’t produce any noise at all so I was sure that it was bad since I could get sound from its input (pin2) connecting it to an external amplifier but nothing on its outputs (pin 7-9).So, I removed the amplifier and put a good one back:

But I was wrong, still no sound at all.So, I went look at schematics of Choplifter that, though runs on different Sega hardware (System 2 while Pitfall II is on System 1), shares the same audio circuitry:

I had not taken into account the pin 6 of the LA4460 which is called ‘MUTE’.This pin when tied low, like its name says, mutes the outputs.So, I went to probe it on the board and, indeed, it was stuck low.I could trace it back to pin 16 of a BA12003 @IC129 (a  Darlington transistor arrays) :

The input (pin 1) was low so signal was not inverted internally (like schematics show) and outputted high :

I desoldered and tested it out of circuit where it failed:

I replaced it with a compatible ULN2003:

and sound was back again.End of job.

I received a CPS1 Strider for my personal collection (B and C board only) from my friend Roger this week. The board was sold as not-working, and when I fired it up, it was sure enough not working:

As you can see above, there were heavy jail bars present in the background sprites. Experience with CPS1 hardware told me one of three things was going on – bad C board, bad mask roms or bad/corroded sockets. The C board is the B-01 PPU variety, which is functionally equivalent to the B-21 PPU. Since I have known working B-21 boards on hand, this was an easy starting point. Swapping the board did not have any effect, so I knew it was either the mask roms or the sockets at fault.

In order to verify the mask roms, I removed them from my board, and set my Superpro 580u programmer to HN27c4000g (which are pin for pin compatible the HN6204P mask roms capcom used). Strider is a very strange board in that the etched rom numbers DO NOT match with the PCB. I turned to mame source code to determine which rom file correlated to which mask rom. Sure enough, the FIRST rom I tried to verify complained about Pin 12 not having connectivity. Some times when you read mask roms as eproms, there are pins internally disconnected, and that is OK. This was not one of those times. I referenced the HN27c4000g datasheet to determine that Pin 12 was actually for Address 0. This address line is 100% required for the rom to function.

Today happened to be my lucky day. I had ONE and only ONE 27c4000g eprom on hand. Burned the mame binary to the rom, popped it in Strider, and the game was back in action!

I played a few games, did not observe any other abnormalities. I wish all repairs could be this easy! Another great Capcom game has been preserved!