HP 46 Desktop Calculator from 1973 

Found one for $10 a few years ago in a thrift store. Thought it was just an old printing calculator until I moved the stuff on top of it and saw the HP logo..

Beautiful machine, nobody will ever make this quality again

I found one of these yesterday beside a recycling container. It was soaked with rain, but I brought it home anyway. Its sitting by the furnace now, drying.

I recognize the shapes of the keys from HP's 264X series of terminals. HP always built great keyboards during that time.

For reference, here is a scan of the HP-46 Operating Guide: literature.hpcalc.org/community/hp46-og-en.pdf

What a lovely machine, I'd grab one of those if I happened to see one at a reasonable price. The printer looks like it's an EP-102 (Made by Shinshu Seiki before they changed to Epson) - they're quite simple once you get your head round their operation, and if you fancied taking the machine apart to investigate the printer, the printer is usually mounted on 3 or 4 rubber suspension screws to the chassis, with an edge connector to the PCB and one earth wire screwed to the chassis of the printer. The paper feed fires a solenoid which engages a toothed rack with a gear on the permanently spinning number drum - the rack is then driven downwards, moving the ratchet pawl that drives the paper roller down one tooth. When the rack gets to the bottom of it's stroke, it springs away from the gear, and the whole assembly moves back to it's rest position, driving the paper roller upwards by one notch. They are a noisy printer but yours does appear to be making some extra noise, possibly because the rack is skipping on the gear, or maybe the paper feed (and also the ribbon advance mechanism) is too tight. However, your unit sounds right when you press the manual advance button, so maybe the solenoid isn't firing for long enough when it auto feeds. If you do take a look at the printer you can rotate it by hand and observe the operation of the paper feed (it rotates in the direction so the number drum moves upwards past the ribbon and print hammers. I did do a couple of videos recently, looking at and repairing an EP-102 printer, but I didn't dwell on the paper feed so you won't see that much there. Also, if you do go inside these machines, obviously disconnect the power first and wear an anti static device to reduce the risk of static damage to chips (a proper anti static bracelet with a wire, the wireless ones are fake!!!) - you may already know this, in which case, just ignore this bit. HP-97s are ace, but seemingly so fragile - I have one and went through the process of making it a new battery pack, then fixing the paper feed rollers in the printer - everything was working fine. Then I went to great expense and bought some magnetic cards, and then replaced the rubber drive tire on the card reader, then went through the process of tweaking the card reader until the card speed was correct and it would read/write cards. Then half an hour later the calculator died, multiple tests and oscilloscope readings later all point to a fried chip, but as they are made of pure unobtainium, it's unlikely I'll find a replacement. I'll keep playing with it from time to time, in case I can find a more fixable issue. All the folks say never to run one of these off the power supply when there isn't a battery installed - with hindsight and having seen the terrible design of voltage control in this model, I'd go one step further, charge the battery out of the machine, or with the machine turned off, and run the machine off battery alone. That's my ramblings for today, cheers for another excellent video.

Restored one of these with a bad LED block. Rebuilt the power supply section, greased and oiled printer gears. German company creates the RED/BLACK printer tape inks. But you can rewind the printer spool and add a little 99%IPA to recharged it if it has dried out. Also have the 9825 restored with a modified DAT drive for use with modern cartridges. The 9x series are fun including the 98S as well as the financial and the my favourite, the 97. Cheers, Geoff in Vancouver.

I saved one of these from the trash (!) some 10+ years ago. The printer was just as noisy as in the video (if not more so), but it was otherwise fully functional. STUPIDLY I decided to downscale my collection a few years ago, and sold it off, as I already had an HP-45. What a dumb mistake that was! I _really_ regret that now. These things are really built like tanks and incredibly well engineered. The HP-97 (which I also have) is pathetically fragile by comparison, as was pointed out in another comment. You could pound the keys of the HP-46 all day until your fingers fall off!

Now that's a keyboard!

When you said, 'card reader' I heard 'carburetor' and for a split second I stared at the screen thinking, 'Huh'?

Wow, it has arcsin and arccos functions as alternates for the sin and cos buttons? That was a sweet feature for 1973. Saves you from having to do arctan(x/sqr(1-x^2)) to compute arcsin/arccos.

So...no Queens problem program this time?

I recently bought a 9810A, and it's huugggeee! I had purchased a HP-97, but the seller dropped the ball and I got my money back. Oh well...