The dark side (Ti-59) Message #1 Posted by Cristian Arezzini on 7 Jan 2013, 6:25 p.m.
I hope I'm not going to be banned for daring look at the other side! :) And I thought you guys here could help me...
Basically, after lusting over the HP-67 for years (it's my personal holy grail), I realized I just can't justify spending so much money on a calculator; then I found on eBay many auctions for the Ti-59. It looked like a solid and "serious" calculator, and it had a mag strip reader... So I placed some bids. I got one (calculator only, with leaky battery but contacts OK) for about $20, and another one (with PC-100 printer, no battery, no corrosion) for about $25. I thought that maybe I could make at least one fully working...
One came with its (US) power supply. Since I was in the US at the time, I tried it, and it had some weird behaviors... it would basically run, but after doing something that involved programming or registers, it would hang. The weird thing is that after it hung, even power-cycling it wouldn't help... it had to be left off and disconnected for quite a long time before it would work again. I assumed a dead/dying memory chip...
The other was working perfectly. But since the PC-100 had no key (I know, I should have checked) I had to physically dismantle it to be able to remove the calculator.
Anyway, back to Italy, I tried powering them up with a stabilized 5V power supply, and... they both seem to work perfectly! They pass the self test, and they read cards without problems. I'm amazed... no "gunky wheel" problem here! What could have caused the first one to start working fine? It could seem like a power problem...
I used a 5V power supply because the original is a standard transformer that provides 3.3V AC; but being the US version, made for 110V, I couldn't use it; and I read somewhere that a 5V CC can be used instead, because the diodes in the rectifier keep the voltages at acceptable levels. Do you think this is correct?
The calculators don't seem to complain, they both work perfectly. After several minutes of use, the ROM stack and the diodes get slightly warm, but not hot. Should I stop using this supply? I wouldn't know how else to power them, as I can't source a proper "official" 220V supply...
Thanks,
Cristian
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