Hi Guys, I've an issue with a Mega CD Model 1 unit rejecting discs after a short while playing and I could use some pointers. It's the JVC drive variant so, like the parts, information is harder to find than the Sony drive variant. Were it a Sony drive, I'd have already replaced the optical pickup as part of troubleshooting. Like all good Mega CD stories, mine began by buying it as "untested" on eBay. It was dead on arrival, but I changed the main fuse inside and all seemed well, initially. It's worth noting that it can play through an entire audio CD with no problems at all, including plenty of selecting tracks back and forth - no issues with seeking on pressed discs. I don't have an original game to test and am using CD-Rs only. Have tried various combinations of media (including Taiyo Yuden), burners and write speeds all with the same result, which is that the console starts up the game perfectly smoothly with no skipping, loading delays or anything of the sort, and plays very well for a few minutes. After which, the next time it tries to load, it will endlessly click and spin, the sound I'm almost certain is that of the laser popping up and down trying to read the disc. My test, at the moment, is to leave it on the Sonic CD start screen and let it go through the FMV sequence, do a few level demos, after which it will happen. Playing the game is the same, it'll just crap out at the end of the level. Same goes for Robo Aleste. I've tried nudging down the resistance on the laser pot to help it with the CD-Rs, interestingly this did not help even in the slightest and, past a certain point made the problem worse, so I set it back to where it was in the first place using a multimeter. The fact that it initially reads CD-Rs perfectly well, and increasing the power did not help, leads me to think that the problem is not the laser itself. The unit doesn't seem heavily used. My next stop is to replace all the capacitors - to my mind, a problem that appears only after the unit has been running for a few minutes could well be capacitor related. My question, before spending an afternoon recapping the entire machine with my average soldering skills, is if this step makes any sense to anyone, or if they know that the problem lies somewhere else. If recapping doesn't help, then I'm shit out of ideas and would possibly look into buying a second one with a Sony drive for parts. At least those drives can be repaired affordably. edit: I've bought a pressed game from eBay to test, too. Road Avenger
The caps need to be replaced, period. Bad caps can cause all sorts of erratic issues but they're not the boogeyman people think they are. As for the laser adjustment not helping I'm not surprised. The service manuals have specific waveforms you should look for when using an oscilloscope because there is more to adjusting lasers than simply upping output power. Recapping and laser power adjustments are the go-to scapegoats for many problems. Caps that old need to be replaced and I'd suggest eyeballing it for a cleaning too. Any leaks will eat the PCB.
Hi Guys, Thank you for the advice and information. I intend to recap the system for longevity regardless of this issue. But I do have an update: The pressed copy of Road Avenger arrived and it plays without any issue at all. It's been running for a good 30 minutes now cycling between the boot screen and the demo FMV, high scores screen etc. CD-Rs do not manage this long and last a few minutes at best. This makes me think the issue not necessarily capacitor related in the immediate sense. Does anyone know of good practices to get CD-Rs working well on this JVC Optima 5 unit, considering I've already tried two different burners, write speeds, and both Verbatim and Taiyo Yuden (JVC branded) media? Is there some more specialist media that will help? Thanks again.
My MEGA-CD unit has a SONY drive. When it errors out real bad on disc read, both leds start to blink and it opens the tray, spiting the disc. I believe that behavior is determined by the CD BIOS, not by the CD drive.
