Hi,
Have you posted the M100 service manual to Archive.org so the world can have access as needed? ============================================================================================== C U L8r, °|° Walt Perko °|° "Kids ... teach them the good stuff, and they still learn the bad stuff on their own." http://www.R2Pv1.com/ RoboGuts™ Intelligent content for 3D printing making S.T.E.A.M. education better, easier and more affordable Experiments to learn how to use various Electronic Components, Structured Computer Programming, Phonemes for Speech &Song in any language, and Art. "The World Needs a New Economic Model" ============================================================================================== Sent from the Cyber7 From: M100 On Behalf Of Erik Keever Sent: Friday, July 4, 2025 11:25 AM To: [email protected] Subject: Re: [M100] M100 garbled screen Hi Thomas, You can get a scanned copy of the M100 service manual online for free which should prove helpful. If it didn't weigh 60MB I would attach the whole kit, but here's the lcd & keyboard no-work flowcharts (pdf p59+60). Everything that's wrong seems to have in common a secondary bus coming off the PIO chip: The LCD, keyboard and clock (and printer port). That the bottom half of the LCD is repeating itself identically (cross your eyes - identically) every 64 horizontal pixels says that something is haywire with writes to the lower 5 HD44102 chips (that the lower CS lines are stuck together) even if they themselves appear to be driving the LCD correctly. If M18 is working and generating the timer pulse, you might try localizing the fault by - unplug keyboard & cold start, see if screen stays drawn correctly - plug kbd, unplug lcd, cold start, press enter b e e p enter to see if it's now scanning the keys Hope this helps, -- Erik On Fri, Jul 4, 2025 at 5:56 AM Thomas Morehouse <[email protected] <mailto:[email protected]> > wrote: Friday update: Batteries replaced with fresh AA alkalines yesterday (Thursday). Left powered off overnight to recharge backup battery. Powered up this morning, but no change. See attached screen photo. The screen clock seems to be working, but date never changes from 1/1/1900. Top four lines of screen appear normal, but below that, definitely not normal. The "center" screen line consists of constantly changing characters. Lowest screen line appears to be reiterations of "Bytes free" - without the "Byt". None of the keyboard keys have any effect; when "cursor" is over BASIC, hitting Enter changes nothing - screen remains unchanged. I've done several Cold Starts (CTRL+Pause/Break+Reset) and (CTRL+Pause/Break+Power switch), but no apparent change. Note: when I do a Power On, the screen quickly shows the correct original default M100 screen, then immediately changes to the garbled screen. Onward through the fog! Thanks. Tom M.
