Nmitchn47 Posted February 18, 2020 Share Posted February 18, 2020 Hey guys, just received my first Fairchild Channel F System 2 as a bday gift and was told it wasn't working. System turns on, led light is on and screen shows vertical lines in green, black & white. No sounds when anything is pressed. Unhooked the ribbon cable from the cartridge reader and no change as well. I swapped out the SL31291 chip with my Fairchild System 1 and it worked just fine, so it tells me the CPU is fine. No burnt spots or heavy oxidation on either side of the board. I looked into the VES manual and the technical guide is suggesting it's a possible PSU problem. Since this system is more compact, I can not make out what chip does what to isolate my problem. Anyone knowledgeable with this or the grandstand clone? - SL31291 (CPU) - SL31253 ?? - SL31254 ?? - FCM 9102 ?? - FCM 9101/N ?? - SCM90004C (x4) (RAM) I'm going to check voltages tonight to be certain I don't have a feed problem. Thanks. Quote Link to comment Share on other sites More sharing options...
Nmitchn47 Posted February 24, 2020 Author Share Posted February 24, 2020 Power supply is good, capacitors and regulators are working. Definitely a chip issue at this point. Hopefully someone can chime in on what the chips are, primarily FCM 9102 & FCM 9101/N. Thanks! Quote Link to comment Share on other sites More sharing options...
Nmitchn47 Posted February 25, 2020 Author Share Posted February 25, 2020 7805 regulator was bad, open output leg at 153v. Checked it before and thought I read 5.2v, but after seeing high voltage at the F8 Chip, I went back. System purrs now. 2 Quote Link to comment Share on other sites More sharing options...
student Posted November 28, 2021 Share Posted November 28, 2021 Resuming to add info some: - SL31291 (CPU) = should be 3850 CPU - SL31253 = should be one of the 2 3851 PSU - SL31254 = should be the other one of the 2 3851 PSU - FCM 9102 = seems to be used for controllers/audio/buffer - FCM 9101/N = seems to be used for video; in some units it is labeled FCM 9111, maybe a newer revision. Both FCM 9101 and 9102 seems to be chips integrating other components/circutiry that can be found on early fairchild hardware revisions (probably to save costs). Quote Link to comment Share on other sites More sharing options...
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