Symptom: No RGB output
Cure: Traced the Red signal back to pin 6 on an LS32 (IC57) on video board, it was dead. socketed and replaced the IC and everything is back
Note: This was a (Super) Bobble Bobble bootleg board but I think the majority of the layout etc is the same
Had this original Commando board for a while now but never been bothered to make an adapter up for it. Even though it may look like the JAMMA pinout, it isnt.
The original fault was garbage on screen
It turns out that in the back on the manual (found on the net) are the schematics for this board and they are nicely split into relevant sections too. After a little while of following them through I started checking the relevant inputs and outputs of the associated TTL.
I found a 74LS74 with a couple of dead pins which I removed and tested again in the Chipmaster
Fired the game up again and the backgrounds were now clear but there was still some garbage. After a little more probing I found a 74LS138 with a dead output
Replaced this and tested, the game now works fine and it also ended up being the Japanese version of the game, Senjou no Ookami.
The screen is a little off centre but this is due to my CGA – VGA adapter not being setup properly for the game.
This board had no sound, a common fault with Double dragon boards.
I Replaced the 3 op amp IC’s as they were giving no output and the sound is fully working again.
Nice and easy
The game had way too much yellow on screen, almost impossible to see anything other than yellow.
I Traced blue/green circuit back to palette RAMs K8 and K9. Both looked fine on the scope so had to desolder the pair of them. The RAM at K8 failed a test . Socketed and replaced the faulty RAM with a 2018 and tested.
All working fine
This board didnt boot at all, looking underneath it was obvious why. There was a huge gouge in the board right down to the board fibres that cut through about 15 tracks.
It was just a simple case of reconnecting these tracks with Kynar wire. The board now boots and plays fine.
