> -----Original Message-----
> Jim, this sounds like a fantastic solution to one of my problems. I
> don't need in-circuit charging (I always have spare NiMH AAs, but I
> rarely travel with an AC adapter) but I would love for the low batt
> light to actually provide some function again.
Yeah, same for myself - although for different reasons. I alternate between
rechargeable and alkaline batteries, but I most frequently run the machine off
a small USB phone charger battery (because it's perfectly happy taking 5V
instead of 6V at the barrel jack - low battery indication doesn't start until
4.2V and auto power-off is at about 3.7V IIRC so there's no issue running the
machine on 5V all the time, it's just like being on half-exhausted batteries).
I keep a set of AA batteries in the machine just to keep the memory alive when
I disconnect my phone charger battery.
If I were going to use my machine on rechargeable AA batteries more frequently,
I think I'd rather do what you do and have two or more sets to swap out in an
external charger rather than have to plug my whole model T in for charging any
time it's dead. Arguably, my use case (usually using it with external power)
might be the best for having it internally charge the AA batteries, but that's
one thing 5V is not quite high enough for - I'd have to use a 10 ohm (or lower)
resistor, no diode, and just make peace with the fact that the AAs would never
really get fully charged... and then they'd get roasted if I used the machine
on a 6V supply. :(
If I were going to do this for my machine, I'd want to install a little dpdt
switch that would mimic the jumpers in the T200 (which clearly were meant for a
switch that they decided not to include - they're right next to the memory
power switch and you can see a rectangular impression in the bottom case where
the cutout would have been molded) - throwing the switch would connect the
battery for charging and simultaneously bridge a 100k resistor onto R108. But
then, where to put the switch... so, I never got around to it. :)
> Is the location for the mod also similar on the 102? I may be a
> hardware novice but I'm pretty sure I could manage to piggyback a
> resistor if I knew where to put it.
Checking the T102 service manual, you're in luck - in the 102 it's still called
R108 and it's still a conventional through-hole resistor instead of a
surface-mount device like most of the rest of the resistors. On page 7-4
(which is page 73 of 111 in my PDF copy) you'll find the main PCB bottom view,
and R108 is down at the bottom edge of the board as shown on that page, right
next to the round power transformer OT2. This would be the underside of the
front right of the board as it's installed in the machine. It shouldn't be too
hard if you have moderate soldering skills to dead-bug piggyback a 100k
resistor onto R108, or solder it to the pads on the top side, whichever you
feel most comfortable with. You'd probably want to extract the board from the
bottom case to have a look and be certain you've got the right resistor even if
you decide to solder your mod on the top side. (In the M100 the resistor in
question is in a clearly-marked neat row of resistors right on top in the power
supply section, so you could do this without doing any more disassembly than
splitting the case and folding it open...)
jim
