Today we have some new PAL dumps from these PCBs:
Got a Rabio Lepus (japanese release of Rabbit Punch, a cute shoot ’em up released by V-System Co. in 1987) in lot of faulty PCBs.Hardware is made of a CPU and a VIDEO board:
Board had a graphical issue, sprites were splitted and misplaced:
Usually this kind of problem indicates an addressing fault so wrong address are generated hence wrong data are read/written.Sprites data are stored in six devices (four 27C256 OTP ROMs and two 28 pin 1Mbit MASK ROMs)
Reading them gave good dumps but the logic probe revealed that address line A7 was stuck high in all of them (address bus is shared)
Tracing this address line back lead me to an output (pin 19) of a 74LS273 @8A, the corresponding input (pin 18) was floating.All the other outputs were active (generating the other address lines for sprite ROMs) and inputs were toggling too.Each input is connected to a data line of a near 2k x 8-bit static RAM @10A so following this logical arrangement I figured out that pin 9 (data line D0) of the RAM should have tied to pin 18 of the 74LS273 but it was not so :
I restored the connection with a jumper wire and this fixed the issue:
As I expected, doing a visual inspection on solderside revealed a severed trace:
End of job.
Today we have some new PAL dumps from these boards:
All dumps have been successfully tested back on respective PCBs using GAL16V8 targeting devices.
Ace’ recently tested E-Swat (317-0130) set and confirmed it works.
Thanks to Ace’ for the feedback.
Got this X-Men PCB for a repair :
As often happens on Konami boards that use hybrid audio module (the ‘054544’ in this case) audio was horribly scratchy and loud:
Electrolytic capacitors had already been replaced with same type but this obviously was not enough:
So, I removed the module from PCB and decided to fully service it:
I replaced with new parts the 4558 OP-AMP (I used a compatible LM358) and the AD1868 DAC as well:
At same time I reinforced some poor connections :
Lastly, as icing on the cake, I varnished with black laquer :
As always I do, I installed on PCB a couple of 1.778mm female round machine-tooled strips.This was the final result:
Time to test :
Job done.
P.S.
For the uninitiated, the ‘054544’ module has been reproduced, you can read more about on these threads: