Today I’ve dumped the PALs from an original Thunder Hoop PCB (a weird and funny platform game by Gaelco).Devices were four unsecured GALs (two GAL16V8A and two GAL20V8A) so I could read them in a normal programmer and successfully test dumps back on board.
I bought this faulty Point Blank PCB for cheap on Ebay:
Seller said it had graphical corruption and was missing a primary color and sound.When I powered it up I actually had sound but the other two issues were there:
The missing color was the green, tracing the pin 12 solderside back from JAMMA connector I found the culprit : one of the three SMD transistor ( each of which drives a color output) was missing:
Green was so restored :
but graphical troubles were still there.Inspecting the board I found that some pins of the custom C355 were smashed:
This custom handles the motion objects (sprites) and my issue concerned this part of graphics.Having a spare Namco NB-1 board I opted for a replacement of this ASIC :
After some work and pads rebuilding, I ended up with this result:
In this way graphics were completely restored but sprites had jailbairs:
Pressing down the board fixed the issue temporarily, inspecting again the board revealed a liften pin on a TC51832 (62256 compatible)RAM @12R:
Resoldered the pin and board 100% fixed.
Today I dumped the PALs from a bootleg of Terra Force.Original devices were two unsecured PAL16R4 whose dumps I successfully converted (using PALtoGAL utility) and tested into GAL16V8 targeting devices
Not a real repair but just a quick “dirty” fix for this Konami Teenage Mutant Hero Turtles PCB :
All was fine but the music played at the start of a game (when turtles jump from palace) was missing :
A usual I started my troubleshooting with a visual inspection and I found soon the culprit.One of the two 640KHz ceramic resonator was missing:
I took it from a dead donor board :
and once fitted the missing music was restored.End of (small…) job.
I had a spare Sega System16B ROM board type ‘171-5797’.Originally it mounted the E-Swat ROM set but I decided to convert to Golden Axe since I missed this game in my collection :
Atter burning the Golden Axe MAME rom set, I powered the board up and game was fully playable but with a noticeable sprites issue:
Judging from fault, I immediately thought about an addressing trouble of the sprite EPROMs (27C020 devices) so I went to check for continuity of their address lines.They were properly daisy-chained each other but the pin 30 (A17) of all of them was not connected to any pin of the ‘CN2’ interconnect (signal to address lines come from motherboard) :
Lack of signal on this A17 address line was confirmed also by my analog scope (good signal on left, bad on right of the picture below):
So, the trace had to be broken under the ‘CN2’ interconnect.Being not available schematics and wanting to avoid to desolder the whole connector, I soldered the end of a wire to PIN 30 of a sprite EPROM and with the other end I touched each pin of the ‘CN2’ interconnect that gave me no continuity until I hit the right one restoring correct sprites:
Lastly, I made the fix permament holding the wire with some hot glue:
That’s all for today.