Texas Instruments TI-55. Modified to use a 9 volt battery

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The Texas Instruments TI-55 calculator was powered with the BP-7 battery pack. It was connected with a proprietary 3 pin connector. The battery pack was charged with an AC step down transformer. If the battery pack failed, the calculator could not be powered with at AC power brick, because the battery pack contained the rectifier.
The TI-30 calculator used the nearly identical BP-8 battery pack. The only difference is that the BP-8 used a standard 9 volt battery type connector. The TI-30 could be powered with either a 9 volt battery, or the BP-8 battery pack.
In this video, we attach a 9 volt battery connector to the TI-55, so that it can be powered with a 9 volt battery.

Опубликовано:

24 дек 2019

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Комментарии : 33

@markbanash921 4 года назад

Thank you! I recently picked up a TI-55 so I could use it as I did when I was an undergrad. This was immense use in cleaning everything up and putting it in order

@markw208 2 года назад

As the others have said, “Thank you” for this video and showing us how to resuscitate an old favorite. Just for nostalgia I wish TI and HP would make a homage calculator with new features but LED display

@CalculatorObsessed 3 месяца назад

Great video. Remember being very annoyed when I was younger and trying to get my calculator back working on the cheap that TI chose to swap the red and black leads around. Glad you’ve documented it properly. Be careful though if trying this with other TI Majestic range of calculators though. Some of the battery packs output different voltages, eg the BP6 for the SR-51-II and some early TI-57 output 2.4V!

@jclocks1661 2 года назад

Thank you! This calculator is older than me, picked it up at a secondhand store, absolutely love the vintage aesthetic and display. Using this guide helped safely disassemble it, and I am planning on soldering in a 9-Volt plug due to battery corrosion. Appreciate the vid!

@caiowerner3286 3 месяца назад

This TI 55 was the usual calculator when I began highschool, but at time I bought a HP34C

@andrewwasson6153 Год назад

Cool video. I’ve still got mine from 1979. I worked all summer so I could afford to buy it. The book that came with it had more advanced algebra concepts in it than we were learning in high school. I had a slight head start before getting buried in the dust. I swapped out my leaky old nicads for a set of Lipo AAA batteries. I’ve got a Ti58C as well. I did the same swap for new cells on it. The old school Ti Programmable is pretty cool.

@petermaquine8173 2 года назад

Thank you. I just got my hands on a TI-57 and without help I was able to open it to clean it without much headache.

@imagerep 3 года назад

I have an SR-40 (since '77) that uses a BP-8 pack, like your TI-30. Having lost the AC adapter that uses a proprietary connector, I will have to use an 9V cell instead. Your video/audio presentation was excellent!!

@c.davidgraves4848 3 года назад

Thanks.

@narcisorodriguezb8813 4 года назад

Perfect, i have one TI-57. I convert to 127 v ac / 9v dc device. Tanks for tips.

@botronics 2 года назад

I was able to use a rechargeable 9 volt lithium battery (FlePow). Not all 9 volt batteries have the same thickness. 15.8 mm thickness of the FlePow works. With a zero, the calculator uses 11 ma. With all 8's on, the current is 37 ma.

@pepekuri8 2 года назад

Dear friend, thank you very much for this excellent video. I have two SR-51-II and the battery pack had two 1.2v rechargeable batteries but ... it has 3 wires (Blue, white and green), and the circuit that must step up to 9V and converts AC to DC doesn´t exist! It's just a bare wire-circuit without any component! it'looks as if it´s only function is to hold the two batteries together and that's all. Any advise you could give to me? I don't want to mess it up and to burn the calculators. Thanks again! Really appreciated! Kind regards!

@keywestskoko 3 года назад

I recently acquired a TI- MBA financial calculator, which was put out by TI around the same time as the TI-58/59. It too was constructed with a similar battery pack which is not longer working. Would you happen to know whether I could do a similar replacement with a 9V battery? Also, would I need to switch the leads (i.e., red to black & black to red)?

@c.davidgraves4848 3 года назад

According to "Datamath Calculator Museum", the TI-55 uses the same BP7 battery pack as the MBA. So the 9V battery switch should work the same for both. Note: since I do not have a MBA calculator to examine, I can not be 100% certain. www.datamath.org/BP_List.htm

@koolty 4 года назад

Good！

@michelemarchese259 4 года назад

One question: the TI-55, if I'm not mistaken, works with 2 1.5 volt batteries (1.2 volts rechargeable) or so it seems from the container (2 AA batteries), therefore 3 total volts. The TI-30 works directly with a 9 volt battery. Was the TI-55 powered with 9 volts instead of 3 volts not damaged?

@c.davidgraves4848 4 года назад

The BP7 battery pack of the TI-55 did contain 2 NiCd batteries. That is 1.2 volts x 2 = 2.4 Volts DC. There is a DC-DC voltage converter inside the battery back that converts the 2.4 volts DC to 9 volts DC. The output at the terminals of the battery pack is 9 volts.

@michelemarchese259 4 года назад

@@c.davidgraves4848 Ah understood. I didn't know that circuit was a voltage converter So the final supply voltage is 9 volts. So ok for the power supply with the 9 volt battery. Ok! Thank you.

@CalculatorObsessed 3 месяца назад

It’s a good question though, as the BP6 battery used in some similar calculators output 2.4V, so you need to know about your specific calculator before trying this.

@DieterZakel Год назад

Can I buy the panel of magnifier lenses for the numbers somewhere as a spare part?

@c.davidgraves4848 Год назад

I have never seen that part available.

@heyhey3652 2 года назад

What is the price of a ti 57 ?

@weedmanwestvancouverbc9266 3 года назад

Dad got his when Seaspan upgraded efucation for it employees and got these for $500. He gaveme it in 79 when I learned trigonometry and logs.

@andrewwasson6153 Год назад

I bought a Ti55 in 1979 for about $50 or $60 from the sears store that used to be down near waterfront station. I might have bought it from Woodward Oakridge but I think it was sears.