https://archive.org/details/TandyM100ServiceManual is, I think, the best copy I've found
On Fri, Jul 4, 2025 at 2:32 PM Walt Perko <[email protected]> wrote: > 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/ <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" > > ============================================================================================== > > [image: BillyBotAvatar-2centsStamp-c] > > 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]> > 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. > >
