💾 Archived View for uscoffings.net › retro-computing › systems › Tandy › 1400LT › hard-drive-battery… captured on 2023-07-10 at 15:04:57.
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#: 119047 (H) S5/T1000/1400/3000/4K
05-Oct-88 22:58:41
Sb: 1400LT Hard Disk
Fm: Stephen Lankton 70305,1142
To: jim tilly 76010,3227 (X)
Jim, here is the fix I am using on the LT1400 for the problem I used to have
where the use of the HD with the power adapter would discharge the battery. I
unscrewed all the things necessary to get the mid chassis out, disconnected
the red and black wire to the power suppy, unbent the little tabs on the PS
cover and removed it, removed the PS board with 4 screws. On the 3500 there
is a resistor in the lower right (as you look from the on/off switch side to
the PS) and on the 3500A it is on the upper-left of the PS board. This is a
part named R554 on the board with white paint. It is a 27 ohm resistor (mine
was red, purple, black, red bands on baby-blue). Cut this out or unsolder it
and replace it with an insulated wire. Now put this resister in the wire
from the hard drive controller to the battery. Cut the red wire between the
battery clip and the little black rubber thing on the wire from the HD
controller board (the black rubber thing is a fuse). Solder the resistor in
there; a 27 ohm 2%, 2 watt should do it. But remember to put shrink wrap on
the wires first AND you must do one more thing. Put a diode in parallel with
this resistor. It can NOT, repeat NOT, be purchased at Radio Shack. It must
be a Schottky barrier diode and no Archer/Radio Shack part is equivalent.
Mine is a ECG586 and I am sure that an ECG585 will work. I tried the TNE585
and it is NOT equivalent and I also tried the Archer/RS 1N4001 and it is NOT
equivalent. I should be a 1N5817 Schottky and the ECG works fine. Solder
the anode end (the non-banded end) toward the battery. Then put the heat
shrink on it, tuck it in, connect the red and black wire clips and cover to
the power supply. screw it all back together and it ought to work just fine.
$2 worth of parts, a soldering gun, screw driver and tape or heat shrink are
all the tools you'll need. Oh, yes, and about an hour of time.
#: 120460 (H) S5/T1000/1400/3000/4K
08-Nov-88 07:36:23
Sb: 1400LT Hard Disk
Fm: Stephen Lankton 70305,1142
To: Ellen DiPiazza 72747,544 (X)
Ellen, the CMI 20meg. HD sells for about $755 from Marymac company in Texas
and is the very same one Tandy installs fro $1200. You must also make the
change of the resistor and diode I wrote about if you want to get the longest
battery life. The HD plugs right in the drive B: slot (which comes out, of
course) and the cables just plug right in. The battery plugs into it -- all
with existing wiring. The controller brd. slips in the Tandy board slot and
bingo...it works right off the bat. The docs are good...very good. The change
in the diode I wrote about it NOT NOT NOT hard if you can use a screw driver
and soldering gun AT ALL. But get the exact right diode and not the RS
equivalent! RS repair installs the HD IF and ONLY IF you buy Tandy's as far
as I know. Marymac's JIM might put their's in for you if you talk sweetly to
him. I thought he was very flexible. It is all portable and durable. Battery
life is about 3-4 hours with it. The model 3500 or 3500A is an indication of
a minor change to the PS (which seems to be rather insignificant) -- this
serial number is stamped on the ID plate on the bottom quite clearly.
Finally, I don't know a bit about the 5.25 inch drive, sorry. I suspect the
logic of the floppy control board (on the drive) must be the same as Tandy
expects it to be and IBM may or may not match. How about checking the
question with someone like Ray Reyes on this sig. (or you can find him on the
Tandy2000 sig...he is very informed about a number of things and that may be
one of them.
#: 131604 (H) S5/T1000/1400/3000/4K
15-Jul-89 21:45:29
Sb: #131556-Hard drive 1400LT
Fm: Rusty Hill 76220,1602
To: Jim White 72407,1031 (X)
I wrote an article for the June PCM. It discusses installing a hard drive in
the 1400lt. The only REAL drive manufacturer I know of is CMS Enhancements.
Their drives from non-Tandy sources go for $760 and up.
There is a resistor on the power supply board which needs to be shorted in
order for the disk controller to work correctly; it is r554.
There are two ways to re-install protection for the battery.
1) place a 27 ohm resistor, parallel SCHOTTKY diode in the battery
from the controller. If it is in the red lead the band on the
diode should be away from the battery. This resistor should be
1 to 2 watts.
2) Get New Pathways Mark 31A current limiter/protector and insert in
the battery lead. The Mark 31A acts like a 10 ohm resistor,
Schottky diode combination until the battery starts to pull
150 mA, about the maximum safe current level for a 12v. NICAD.
It clamps the current at this level. Thus it provides a faster
charge and protects the battery from over-current damage.
Your charger needs to deliver over 14 volts at the battery terminal and be
able to provide 1.5 to 2 amps.
These can be gotten from:
New Pathways 140 Walnut St. Shrewsbury, MA. 01545 (508)842-4437
BODEX 224 East Main Marlboro, MA. 01752 (508)481-1027
Computer Plus P.O. Box 1049 Littleton, MA. 01460 (508)486-3193