Today is a good day - an HP-28S saved

[8031Brown]

I recently found a box of my late father's HP "stuff". Manuals for his HP-67, the box, manuals and some app pacs and memory for his HP-41C, even some very old printer rolls. The calculators themselves will hopefully turn-up.

But also an HP-28S that I had no idea that he owned. Batteries left in it for about 15 years and not well stored but a little judicious cleaning of contacts with a bamboo skewer and a set of new Duracells and... it lives. It was complete in its original box with both manuals. Now I have to learn RPL!

__this from a happy HP Prime user - don't judge me

[John Keith]

Congratulations on the save, the HP-28 is a very nice machine, truly revolutionary in its day.

Be very careful when changing batteries- the battery door and surrounding case are notoriously fragile and easily damaged when changing batteries. Also see this recent thread regarding batteries.

Good luck with your search for the remaining calculators, to hopefully be used and enjoyed by another generation.

[rprosperi]

(04-15-2024 07:59 PM)8031Brown Wrote:  I recently found a box of my late father's HP "stuff". Manuals for his HP-67, the box, manuals and some app pacs and memory for his HP-41C, even some very old printer rolls. The calculators themselves will hopefully turn-up.

But also an HP-28S that I had no idea that he owned. Batteries left in it for about 15 years and not well stored but a little judicious cleaning of contacts with a bamboo skewer and a set of new Duracells and... it lives. It was complete in its original box with both manuals. Now I have to learn RPL!

__this from a happy HP Prime user - don't judge me

DON'T use Duracell batteries in any HP Device (or any other device). This Forum is overflowing with stories of how Duracell brand batteries damaged or even destroyed their precious devices. This is not a new phenomenon, HP sent a letter to HP-71B owners in 1984 about the danger of Duracell batteries in a 71B and they made some arrangement (long, long since void) whereby if you could provide evidence of machine damage to Duracell, they would cover the cost of the repair, or something to that effect.

Enjoy your 28S, enjoy learning RPL, and even enjoy thinking of your Dad learning RPL, but get some other brand of N cells in that machine ASAP. Depending on where you live, different quaility brands are available, including Energizer, Varta, Panasonic, etc. These do cost a bit more, but better than paying the price of a ruined machine.

[8031Brown]

John, Bob,

thanks for the advice re. batteries and the cover. Duracell are not the product they once were and I will replace a.s.a.p. In my personal experience I have had good brand batteries leak and cheap no-name ones fare better but not usually for time before discharge.
I don't know if Kodak ever made batteries during their heyday but I have bought some very poor quality cells that have been branded Kodak by a company called Strand, IIRC.
Also Varta and GP brand duds.

I am very happy to have a working calculator and particularly to have the original manuals.

[bxparks]

(04-15-2024 11:46 PM)rprosperi Wrote:  Enjoy your 28S, enjoy learning RPL, and even enjoy thinking of your Dad learning RPL, but get some other brand of N cells in that machine ASAP.

There are people on these forums who say that 2/3 size AAA NiMH batteries are compatible with size N batteries. That could be the best option if that works.

I have personally replaced almost all my batteries with NiMH, about 200 of them according to my spreadsheet. Duracell alkalines seem to leak the worst, but other brands also leak. The only things that I have found not working with NiMH are smoke and carbon monoxide detectors, which are calibrated to the alkaline voltage curve.

[John Keith]

Though 2/3 size AAA NiMH cells seem to work well in the HP-41, I would not recommend using them in the HP-28 for the reason stated above: the battery door. NiMH cells do not hold a charge as long as alkaline cells, and every time the battery compartment is opened to change batteries is an opportunity for disaster to strike.