Got this original Namco Rolling Thunder from my friend Alexander for a repair :
Board didn’t boot up but got stuck on this screen which repeated itself in a endless loop sign that the watchdog circuit was active :
My friend Alexander gave me an hint to troubleshoot this fault pointing me to a bad custom ‘130’
As I swapped in a know good one from a board of mine, game successfully booted but showed a strange graphical fault where the main character didn’t disappear when entering in a door:
As usually I started my troubleshooting with a visual inspection and found a deep scratch on the solder side and after checking with a multimeter I could notice that involved trace was severed:
After consulting the schematics I was sure that the broken trace was indeed in the sprites circuitry :
Restored the trace cleared the sprite issue.Job done.