Dec 292016
 

I received a faulty Golden Axe 2 PCB off of eBay. It arrived as advertised, very good condition, however the video sync is faulty. The seller said that he wasn’t sure if it was his equipment or if the PCB was faulty. The price was nice, so I decided to take a gamble. Unfortunately when the PCB showed up, it turned out the seller was correct – the sync was completely trashed regardless of the monitor used:

I traced the sync signal starting at the jamma edge. This was actually surprisingly difficult to do, largely due to the very small traces Sega used, not to mention the signal starts on the solder side and ends on the parts side (switching sides a few times). After some poking around, I found the sync signal goes DIRECTLY to IC73 (Sega 315-5388). Mame source notes describe this as a “sprite mixer”. Since the sync signal goes directly to pin 42 of this IC (with literally nothing but a ferrite cap in between), I decided this IC was likely faulty. Out comes the hot air…

I pulled a donor IC from another Sega System 32 motherboard that I have that has sustained damage to the PCB. It is beyond repair, but great for donating IC’s such as the 315-5388! I installed the freshly pulled IC to Golden Axe’s motherboard:

  

SUCCESS! The Sync signal has been restored, not other faults are observed. Game is now fixed, working 100%. Another great game has been saved!