Wow! I guess this also means we got some early editions of the M100, huh?
I appreciate you letting me know about the repair bulletin; fortunately
I'm handy with a soldering iron so I should have no problem getting them
swapped out. I'll also try setting the lookback switches away form the
dot in the meantime. Heck, I'll even record the process; I've been
looking for an excuse to make some M100-related videos! :D
Thanks again!
--- Philippe
On 1/13/2023 1:31 PM, [email protected] wrote:
Some of the original M100s have the wrong resistors in part of the
RS232 handshake circuit. The voltage drop is so high that with the
signal looped back it is just barely sufficient. The Backpack
eavesdrops to know when to power itself back up and this minuscule
additional load is too much. The symptom is that the Backpack responds
once and then stops.
I have tried to attach a tech bulletin that Tandy put out back in the
day that describes the fix. The alternative is to set both lookback
switches away from the dot. The Backpack does not eavesdrop in this
configuration so it can't wake itself up. You can adjust the timeout
to compensate.
This is only the third M100 I've com across with this issue. I have
one of them too ? At some point in the future I'll do a video on the
fix per the Tandy tech bulletin.
Jeff Birt
