wall wart for TI-58-C

[Mark Tapley]

At 11:30 -0600 1/12/07, Mike wrote:
>     I just checked my TI-58C, and it does indeed take a 3.3VAC 500ma power
>pack.  The links I posted earlier agree.  The connector is keyed.  The
>part number is AC-9131.  Are you sure that's the right pack, Stan?  The
>references say the TI-58 uses the same AC-9131 pack.

The numbers so far are not totally inconsistent. The wart might 
supply 6.x V open-circuit or low-current, but rely on the battery 
pack to pull it down to 3.3V at 500 mA, running or charging.  The 
circuit diagram on xgistor seems to indicate there's just a 4.7 Ohm 
resistor keeping the bus from being completely battery-limited.

That said, the battery pack definitely contains 3 Ni-Cad cells, each 
typically around 1.1 or so V. (I have had mine apart, rebuilt with 
stock Ni-Cads, ond not fried anything.) Therefore 3.3 V to the 
electronics makes good sense.

One thing I would *not* do would be to plug in the calculator without 
a good battery pack in place, based on the circuit diagram and on 
Tony's advice pertaining to the dire consequences of similar actions 
with HP calculators.

FWIW, there is one more factor in the story. TI made a printer base 
(PC-100?) that you could place the calculator (TI-58, -58C, or -59) 
on to generate printouts. The method of connection was to take out 
the battery pack, and place the cavity that it just vacated over a 
protrusion on the face of the printer, which would then expand to 
lock the calculator into place. (There was also a compartment to put 
the battery pack into so it could charge while you printed.) Whatever 
the power supply in that doohickey was, it circumvented the battery 
completely. If anyone has one of those and could measure the voltage 
on its power pins, that would likely shed lots of light on what the 
calculator expects. (Sadly, mine went at a garage sale while I was 
away from home.)

-- 
                            Mark Tapley, Dwarf Engineer
                        (I haven't cleared my neighborhood)
                  210-379-4635 Dwarf Phone, 210-522-6025 Office Phone