No luck with HP41CV's


I have now purchased my 2nd 41CV from The Auction Site. Both look good from the outside, but each of these beauties fails on me :-(

The first one (no S/N) freezes when I press ALPHA.
The second one (2251S41078) freezes when I press PRGM.
Both are fullnuts. I have tried the various tips from this site, opened and cleaned both of them, shorted the capacitors in order to provoke MEMORY LOST, twisted them a bit, but to no avail.
[ON] plus [<-] awakes both of them until next time...

Is that a known problem of these devices or am I just unlucky?
Any other advice you gurus could give me? I'd love to have at least one that works :-)




if you're located in Europe I can offer to take a look at your HP-41 units,
and tell you what went wrong.

Just drop me a mail at: M a g i c 4 8 g e s @ g m x . d e (remove the obvious)



W&W HP-41CY and CW Turbo owners should also ask me if their unit needs service;-)


Martin --

A few years ago, I acquired two fullnut HP-41's (1980 HP-41C; 1984 HP-41CX) separately via eBay, shipped by commercial air using USPS Priority Mail. Both malfunctioned during routine operation, with weird displays and spontaneous shutoffs -- even though the auction listings had no mention of problems, or stated that all was well. A colleague's fullnut HP-41C exhibited similar malfunctioning.

Standard-service ultrasonic cleaning and targeted resoldering by restored flawless operation that continues to this day.

There may have been some systematic design or assembly defects in the older and more-complicated fullnuts that can cause unreliability over time. Transport in the cold, rarefied cargo hold of an airliner might finish off some brittle solder joints.

-- KS


(((( SORRY I HAVEN'T FIGURED OUT HOW TO FORMAT YET.))))Hi. I don't know if you are looking for yet another hp-41, but I have one, in exceptional condition and lightly used, with card reader, printer, circuits module, advantage module, etc. etc. I am going to "refurbish" it (replace card reader capstan, etc.) and make sure it is in perfect condition, in the next couple of weeks. I was going to put it on ebay but I think I will put it on the classifieds here first and see how that goes. It is in excellent condition. I am a former HP technician, now a senior electrical engineer; I know what I am doing etc. I also have about fifty other calculators in various conditions which I am going to be selling over the next couple of months, as I get them fully refurbished and ready to sell. (I won't sell "as is" stuff unless it can't, or shouldn't, be made as good as possible.. I was an HP calculator junkie in the seventies, member of PPC, etc., until PCs came out and I started up a little company building peripherals for them, etc., and got away from using calculators as limited computers, and just them as calculators (sigh.... those were the days). I was building a collection, got carried away, and, well, I imagine that describes about two thirds of us here, or at least, a lot of us! I was disabled but fortunately, I am recovering and will be starting up my company again with a new pat pending technology I have developed over the past fifteen years, which will have a fairly big impact on the Internet and other networks, wireless, etc., so I don't expect to have much time for the calculators or other hobbies.... and I need every penny I can get my hands on, also! Not that any of this has anything to do with your questions; I just got carried away again and again and again and ... drat! did it again.....&#13;&#10;&#13;&#10;The HP-41s have interesting internal construction. They use flex circuits and some other interconnect methods which will become intermittent or fail entirely over long periods of time (decades), especially in extremely dusty, humid, and corrosive environments. I don't think the designers at HP expected them to still be so popular and so widely used, thirty years later! As time went by, their "battles" with TI and other competitors put downward pressure on their prices, which HP was not used to. Prior to getting into calculators, then, personal computers, HP was used to designing very high-end, specialized products, test instruments, etc. When their competitors forced them to start building calculators for less than a thousand dollars (!), HP went through a "learning curve" to get down to the price points they are at now, and they didn't always get it right. They didn't want to start building products which were as cheaply made as TI and others, but, they had to at least get in the price ballpark, so they worked hard to develop novel ways to manufacture them, unique materials and methods, etc., and they went pretty far out on a limb at times. Witness the infamous HP-30 series, where the circuit board was a kind of "sponge" with the traces etched on it, and the parts were put into a plastic frame, then pressed down against the circuit board contacts when the case was screwed together, without soldering anything to the board! Typical HP overkill and "excessive creativity" (being more creative than necessary just for the sake of it, kind of "showing off". We all did it; it was fun but didn't always yield the best results...). Even though HP was/is a huge company (though it was much smaller when I was there..), when it comes down to it, each product has some person in charge of designing it, with an appropriate team of other designers, technicians, etc., just as a smaller company would have. That team's design decisions will usually be good but sometimes a flaw or weakness can sneak through the review process (which is, I can tell you, NOT like a small company; products are scrutinize pretty closely, at least in my experience there...), and show up in tens of thousands of "white elephants" like the HP-30 line with the sponge circuit boards. I guess that works out ok for some collectors though, as it creates a class of collectibles with unique features which become valuable in some markets later on.&#13;&#10;&#13;&#10;OK, so why am I writing all this? I haven't a clue.... I just did it! I hope I wasn't too boring...Larry


I found the information on formatting; 
too late for the long&#13;&#10; message I just left but at least,
future posts will be&#13;&#10; viewable with only two eyes, if I ever figure this crazy&#13;&#10;thing out!!
(Where is all this garbage coming from? I can't see&#13;&#10;it on my screen until I try to post!)&#13;&#10;Larry



re your format problems: I think you are trying too hard!

I find that just typing into the message window works fine.

Remember to hit two returns to get a line break.

Also, check that your browser doesn't have the wrong character set turned on. All those funny &# characters tend to show up when using extended ASCII (I think). I know that if I type something in WordPerfect and then try to cut and paste, that things like " come out funny. Whereas here, I think that " will show up just fine, as I typed it from the keyboard. So, if you are cutting and pasting to enter your message, things may look funny.



thank you for the insight into HP's inner workings. I guess most people in this forum are fans, collectors or both, and they enjoy hearing stories about their favourite calculator company :-)
I don't want another 41 thank you, but I will watch closely for other electronic marvels you are going to sell.

From your view as a former HP engineer, would you say that faulty flex circuits/brittle solder joints are the most frequent problem the HP41's have today?
That will enhance the chances of repairing them myself (problems with bad electronics components would be much harder to diagnose and least for me)

It seems I will not get around purchasing an ultrasonic cleaner. Any tips what liquid I should use (forum members: please report your experiences!)?

Cheers, Martin

Possibly Related Threads...
Thread Author Replies Views Last Post
  hp41cv memory modules tim peterson 10 2,625 11-07-2013, 11:09 PM
Last Post: Garth Wilson
  HP41CV Mike Powell 12 2,509 10-30-2013, 08:17 AM
Last Post: Mike Powell
  HP41CV Bry Sun 11 2,487 10-22-2013, 12:52 PM
Last Post: Geoff Quickfall
  No luck getting flash disk to work in 95lx Harald 7 2,318 03-18-2013, 08:11 AM
Last Post: Harald
  HP41cv expiriences of a new user Wolfgang 28 4,776 02-13-2013, 08:02 PM
Last Post: Mike Morrow
  A simple question about the HP41C or HP41CV Antoine M. Couëtte 6 1,708 12-16-2012, 04:06 AM
Last Post: Antoine M. Couëtte
  Problem with HP41CV Bruce Larrabee 19 3,459 09-18-2012, 09:29 AM
Last Post: Luiz C. Vieira (Brazil)
  No luck with HP25s Harald 18 3,401 07-21-2012, 09:47 AM
Last Post: aurelio
  HP41CV drains battery. Schematics? Harald 15 3,133 03-18-2012, 09:22 PM
Last Post: Luiz C. Vieira (Brazil)
  HP41CV batteries John Abbott (S. Africa) 3 1,106 03-02-2012, 06:15 AM
Last Post: John Abbott (S. Africa)

Forum Jump: