It looks like the RAM ROM check normally proceeds to a summary screen where it lists Pass & Fail results. The graphics don't look corrupted though, so that's a good thing. With your Gradius II, the board starts up and hangs on the RAM ROM check. If it has corrupted audio, is it music, SFX or speech? How does the malfunctioning board behavior compare to a properly running board in MAME? Is the board not starting up at all? Does it startup but fail a diagnostic check? Does it boot up and run, but have corrupted audio or video? If it does have corrupted video, is it background tiles, sprites, or overlay (fixed) text. Some boards won't boot up normally if a Test or Halt DIP Switch is enabled.Ģ) Identify the malfunctioning subsystem. Some boards need a DIP switch selected to enable Test Mode. Some boards need a little more juice than 5.0V to run, but don't exceed 5.15V if you can help it. A decent entry-level EPROM programmer costs $200.Įventually, you'll also want soldering and desoldering tools - you'll need them to remove faulty components from the board to replace them.ĭecent entry-level soldering tools start at about $150.ġ) Make sure all DIP switches are set to OFF, and that the supply voltage is between 5.0V and 5.15V. I made a tutorial video on using a logic probe to test an EPROM here:Įventually, you'll want to have an EPROM programmer - it lets you dump ROMs, program new EPROMs, test logic chips, and test RAM chips. A decent starting logic probe can be obtained for around $20 from Amazon. You'll want to have a logic probe - it lets you see the logic activity for each line on each chip. A decent starting multimeter can be obtained for around $20 from Amazon. Use it to test for voltage levels on chips and for continuity on traces. I don't know what your current knowledge level of electronics troubleshooting is, so I'll try to explain things as thoroughly as I can without getting too far into the weeds.Īt a minimum, you'll want a digital multimeter. Here's the rundown on my process when troubleshooting a board. I ended up writing a short essay, and we both agreed that the info may be useful for others so here it is: As part of troubleshooting his Gradius II PCB, asked me through PM for a summary of my diagnostic procedure when looking at a board.
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