What do you think of my HP buying prices?


Hi everyone,

I just finished the three purchases (over the last 3 months) of my prefered vintage HP RPN calculators -- I purposely limited myself to the 3 models hereunder, trying not to break the bank, at least for the time being...

So, I paid:
-- $119 for a perfect HP41CV + carrying case (no books);
-- $250 for a mint HP71B + carrying case + books + box;
-- $275 for a mint HP15C + carrying case (no books).

Although non-HP lovers would say this is way too much, after 3 months of daily prices inspection, and considering the perfect or mint status I was looking for, I think it's still OK ... or am I wrong?

Thanks for your opinions!


You paid "normal" ebay prices....


Hi, Emmanuel;

first of all, if they they fit your needs, are in good condition and will be of any use, then congratulations. For what I can tell you, you made very good choices. As I can see, you are not exactly in the business field, right?

If your bank account is still healthy, better. As Thibaut mentioned, normal prices.

Make good use.

Luiz (Brazil)


A bit high for the 71B but otherwise the going prices on EBay.


I think most people who use eBay should expect some bargains and some rip-offs. I've been pretty lucky in the bargain department (2 10C's for a total of $57) and have over-bid on some items ($149 for a very marginal 55).

You have to go into eBay expecting this sort of roller coaster ride. You have to be very alert and very up-to-date not to be taken every once in a while.


Beauty is in the eye of the beholder. If you are happy with your purchases then you paid the correct price.

You have the added support in the fact that somebody else (the loosing bidder) valued your purchases at almost the same value as you did.

Enjoy your purchases.


I even think the 71B price was good, given the fact it was in the box. Wasn't that long ago that the boxed ones were selling for up to $600. I know, 'cause I have the box from my original purchase and I've followed the prices....this stuff goes up and down like the stock market.... if it hits REAL high, I'll have to "sell".

Not sure I can bring myself to part with the ones in my collection with no duplicate, though....



I think you got a fair deal.

I actually don't know if you are referring to the 71B that you got from me but if you are, thanks for calling it Mint. I didn't because it wasn't mint to me. That's how picky I am. But many would call it mint.

I'm finding more and more that there are many sellers (far too many) that aren't collectors that are selling junk and overstating the condition. They don't mention obvious flaws that aren't shown and even sell broken items as working.

I have been on ebay for several years and it is getting to epidemic porportions, when it comes to misinformation.

I am thinking about modifying my Calculator Buying Tips to make it generic in nature (rather than specific to me), and have a list of
collector-sellers at the end. Of course, it will be subjective.

Still puzzling over whether or not I should do this. Good idea; bad idea?

Edited: 4 Aug 2003, 10:42 p.m.


Admittedly, I haven't received it yet, but I must said I bought in total confidence considering the very detailed pictures you made, as well as your very good references.

I hope it's arriving soon in the mailbox :)

Your idea about the generic tips is very good, but you'll have a lot of work since imho buying tips are typical to each "zone of interest" (i.e. buying tips for vintage calculators being slightly different from other areas).

Anyway, thanks for all the answers, and have a nice day!


I wish I had read your "Buying Tips" before I recently bought an HP-67 which was advertized as having "all keys working properly" and the "card reader working perfectly". Unfortunately, neither were and I paid way too much. I guess the only thing I can do at this point is give a negative rating to the seller but he has a "0" history so probably doesn't care.

Tom Scott


Hi Tom!!

I apologize for not knowing, but do you restore calcs? If not, the HP-67 is wonderfully fixable.

The keyboard is fairly easy to repair by polishing the contacts... there are many threads on how to do this. The card reader is also a fairly easy fix, especially if you've done a couple.

Let me know... I've been pretty busy, working 18 hour days lately (everyone is in crisis at once), but I'd be happy to take it on as a project. There are those more knowledgeable than I, but I'm a good technician. (I was a bicycle mechanic for many years, and can fix most anything, sometimes with some help from the kind folks here).

Let me know if you'd like help, and if not, K'pla!



I have been fixing up my old bike lately... you go into a bike shop these days and their "mechanics" have never seen downtube shifters and just blink when you ask for a five gear freewheel. It took seven shops before I found one who could rebuild a set of Campy hubs.


That's sad. Gone the way of HP quality....

I spent three years at a shop in high school, then 4 years as a pro mechanic at a place called Turin Cyclery in Evanston, IL. Our shop was ranked the number 2 in the country, and I was one of the three "head mechanics." I once stripped a bike down to the bearings (no sealed ones then except a few popping up), repack, recable, and re-rubber,etc. in 60 minutes. I was the best. I lived with bicycle racers. Bikes got the good spots-- we sat on the floor.

There are few things I could ever say I was "the best" at. I'm proud of this. I could listen to the sounds of a bike bouncing on the floor and tell how it was adjusted...I was lucky to work at a store that even rebuilt the bikes that were sold as new.

Of course, it was now almost 25 years ago. As my wife would say, "yeah, yeah; nobody gives a sh*t..."

I actually tried to work at a shop during medical school in Kansas City, but few stores cared about quality. "We'll fix it if it comes back" was pretty much the rule.

I suspect finding a shop with quality as a priority is hard to do. And it does take some natural talent; we hired college students for the summer who knew what to do, good kids-- but never had the feel for how to tighten something to the point of, but not past metal fatique, etc. They did it by rote, not by the art. I might break a bolt now and then, not several a day...

I quess there's a strong connection to the restoration of calculators. Making something look and work the way it is "supposed to"... is a spiritual thing. "Zen and the art of calculator maintenance?"

That's why I like this group and this forum... there IS an appreciation of these values and quality calculators.




Hey, Michel! To be honest, I'm taking these repairs as "therapy" for longer than I can recall.

No prescriptions, just good and conscious practice.

Best regards.

Luiz (Brazil)


....always a head mechanic. Was that on purpose or was it punintentional?


Custom frame built by Trek before they did production bikes... Reynolds 531 tubing. Campy cranks, hubs and shifters. Weinmann concave rims. Suntour Superbe brakes. Phil Wood bottom bracket. Regina freewheel and chain. TA titainium/saphire pedals. Brooks Pro sadle.

Over 60,000 miles on it and it still looks and works like new. Now if I could just find a new freewheel and some proper gum hoods for those Suntour brake levers...


I guess I am a "head mechanic" now!

The bike sounds great. I doubt I have any hoods in my parts box, but just might. I have a spare free-wheel or 2, but don't know what configuration.

They must still sell them, no?


I really enjoyed the posts in this thread reagarding bicycle racing,bicycle mechanincs, and classic bikes!

But here is my take on the freewheel issue:

I finally got tired of breaking rear axles on campagnolo 6 speed hubs, and have switched to the far superior cassette style rear hubs. You can still get shimano 8 speed cassettes, and with these, you can make new spacers so that you can emulate the 6 speed spacing (or even 5 speed spacing!) of older freewheels. Then, you change out the locknuts and spacers on the axle, taking the nut to nut dimensions down from 130 mm to 126 mm (6 speed). I have not tried it for 5 speed spacing but think it will work--and you can squeeze a 126 into a 120 mm rear end anyway (sometimes!).

What does this have to do with HP? Well, you have to use your trusty HP-41 (or HP-67) to compute the new spacer thicknesses, offsets etc. To use a cheap modern calculator is blasphemous.


Bill Platt


Hi Mike,

I was looking in the Archives and saw your request for vanity plate ideas. What did you eventually go for? Some of the suggestions were pretty good, even the ones that weren't mine. :)

Maybe you could put up a photo, too.

- Michael


Embarrassingly, I've never followed through. It's a "someday" thing, though.

Sooo..... anything is still possible.

I still like RTN2RPN the best. Nostalgic, like my collecting. Understandable by almost anyone with at least some computer knowledge. And it includes elements of both programming and RPN.

I also like the dual-meaning one: MEM LOST

Fun, but not clearly related to my hobby. Still, universally understandable on some level.....


According to Tom, it was advertized as working. I'm seeing this more and more on ebay. Many shody sellers that are selling junk and leveraging off of collectors prices.

Things to watch out for.

1) Single photos - A single photo is very easy to conceal flaws.

2) Poorly lit photos - Very bright photos are what some people use to hide scratches. Very dark photos can hide other flaws. If you see poor photos, be suspicious.

3) Slight of hand advertizing - Look for what they are not telling you as much as what they are telling you. Some sellers will tell you about a minor flaw but ignore larger flaws. Don't assume that if they tell you something that nothing is left out. Often they leave things out.

4) DOA guarantee - Ask seller if his DOA guarantee convers partially working or to put it another way, partially dead. One ebay seller offers a DOA guarantee but sells broken items. When you try to collect, he says, it's not completely dead so it's not covered by the DOA. Ask seller if his DOA includes partially broken calculators.

5) Look at other auctions he runs. I saw one seller that said, "can't test card reader because I have no cards." Sounds reasonable, right. But he was selling in another auction, cards that he said he didn't have.


Most of your warnings certainly applied in my case. The picture was small and not brightly lighted. The wording was somewhat vague in parts. I did send two e-mails prior to the bidding which he answered somewhat vague terms as well but it is clear now that he was intentionally exaggerating or lying actually.

Tom Scott


Thanks, Michael. I've read some of the repair instructions but I think they're beyond my capabilities. However, I appreciate you offer. I have two HP-67s which both work to some degree. All LEDs work and most of the keys work, but not all (at least they way they should). So, I don't know if it's worth your time or not. It certainly would be worth it to me to spend more money to get a good working unit.

Tom Scott


Well, it shouldn't cost anything but the postage. I'm glad you have others, though: If you only had one, it would be a guarantee that something would go wrong and kill the one I was working on. It's never happened, but there's Murphy's Law...

Having said that, if you want, I'm happy to fix it up.



My revered HP67 is now show a series of zero's thus:

-00000000000 00 . . . . . does this mean the end of a
long enjoyed partnership or can it be restored to full
RPN working order ? Sadly the magnetic tape drive
ceased to work a couple of years ago but I understand that
even this can be resolved.

I literally have scores of manuals but have been unable to use them, although the calculator has operated OK until now.

Who do I contact for assistance - or is the HP67 era now
closed ? ? ?


All zeros in the display is usually a sign of a fried ACT (processor) chip. A common end to HP classics, it usually means the circuit was exposed to voltage unbuffered by a battery. I think this is rarer with the 67, as I think the calculator is designed to operate without the battery. Sometimes they just die.

It isn't completely hopeless, though. Amazingly, a processor from a lesser model, such as the common HP-21 or HP-25 can be used to repair the 67. Of course, you have to find a broken Woodstock or be willing to sacrifice a working unit.

I think I have several bad chips in a box, now. My own "group project" 67 went through 2 before becoming stable and happy. (It's been suggested that static damage was the cause, though I've never had problems with any other calculators. I think it was simply bad luck....)

I can't tell you how to go from here... it's up to you. You could wait until you find a "donor" machine, or you can sell it or trade it. I'd be happy to look at it, but it could be awhile until a "donor" chip comes my way, and the more often you try to transplant, the more the chances of permanent circuit board death....

New ones on eBay go from $150 to as high (lately) as $800. Broken, it's roughly worth $50, or at least IMHO (what I'd pay).



I have found it all too common for a replaced ACT chip to fail a few minutes after being installed. It could be static electricity or heat stress from desoldering/soldering. I use a high dollar vacuum desoldering system with isolated/heat controlled/static controlled tip, etc and still have problems with replaced chips going legs up in the recovery room. I think the main problem is that I salvage chips from the worst looking, most corroded HP21 or HP25 machines that I can find... garbage out, garbage in...


Hi Mike,

It would be wonderful if you made your tips generic. There are several people whom I know could benefit from your page, but would probably be too distracted by the calculator specificity. Also, I could refer people to the page without revealing myself to be too nerdy :-)

Be sure to include the story about the "untestable" card reader and the separate auction for cards :-)


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