So I found a dead Gorf on Craigslist. \u00a0It was an older ad, but was still available when I inquired. \u00a0Dude I picked it up from had done some pretty impressive restorations on some other games.<\/p>\n
Anyway – it was dead alright. \u00a0Shows a blank screen that looked overly blue due to how the monitor was adjusted, no starfield was visible. \u00a0Slid the test switch over and power-cycled, but this made no difference either.<\/p>\n
The previous owner had mentioned that he had done some work on it. \u00a0I saw some of his other previous\u00a0work on other boards of his and while not perfect (some cold joints, or not enough\u00a0solder in some places leaving “pits”), it was not horrible and definitely no worse than what I was doing when I started out.<\/p>\n
Anyhoo, starting with the power PCB – the previous owner said he had already replaced the caps, but I wanted a second look at it, JIC. \u00a0On the solder side of the board, some larger traces has been lifted off the board during some previous repair work (I do not think it was his, maybe someone before him?).<\/p>\n
It looked like the someone used a serious soldering gun to do the work, because there were scorch marks on the board(!) and flux was all over the older work too. \u00a0Continuity was where it was supposed to be, so I guess that while it was ugly, it worked<\/em>.<\/p>\n Hit the previous work with a small wire brush to clean up some of the flux, and reflowed solder on it and the\u00a0connector pins, just to be safe. \u00a0While I was doing this I\u00a0noticed that an IC had two pins soldered together, but each pin had its own separate trace, which looked suspect. \u00a0Verified with the schematics that the pins are NOT supposed to be soldered directly together and fixed it (they are actually supposed to be connected through a fuse).<\/p>\n Powered the game back up and it came up with a rolling screen but I could make out score displays at the top. \u00a0Also was showing some solid “blocks” that made me nervous and some\u00a0color distortion. \u00a0Was able to get the screen to lock with a\u00a0simple monitor adjustment. \u00a0Blocks were just the test screen – I had forgotten that I left the test switch closed.<\/p>\n Game was already set to free play, so I started a game. \u00a0Immediately noticed that some sounds are missing, and no speech. \u00a0Adjusting volume controls did nothing to fix it, but I quickly determined it was channel 2 that was broken.<\/p>\n Checking voltages at the channel 2 speaker shows it at a constant ~14 volts! \u00a0Metering the input to the amp board shows sensible readings that change while the game is running, so I think the input is good.<\/p>\n Taking the amp board out and metering the transistors shows some strange readings, but they were<\/em> in-circuit. \u00a0Swapped the two audio lines at the connector (pins 4 and 6), and I was able to hear the other set of sounds, but still no speech. \u00a0After paying closer attention, I noticed that I was getting a a click or two when I was supposed to be hearing speech. \u00a0So I think I verified that the channel 2\u00a0section of\u00a0the amp is bad and \u00a0the Votrax SC-01 is bad, too. \u00a0That last part\u00a0really\u00a0IS<\/strong> bad, because they are not easy to find!<\/p>\n Decided to shotgun the entire channel 2\u00a0section of the amp board, JIC – this is old hardware, after all.<\/p>\n After doing that I remembered I forgot to actually check the speaker itself. \u00a0Sure enough, it was supposed to be an 8 ohm speaker, but it was shorted. \u00a0Replaced the speaker and connected up the repair amp board and now I have all sounds except speech. \u00a0The mother ship explosion never sounded so good! \ud83d\ude42<\/p>\n The SC-01 chips are getting hard to find and are a bit pricey. \u00a0But I do want the game working fully again, so it might be worth it.<\/p>\n