First time HP-41 owner needs a little advice

Everything about 41C 41CV and 41CX Hardware

First time HP-41 owner needs a little advice

Postby cappy2112 » Tue Dec 06, 2016 5:48 am

Hello,

I've have an HP-15C & HP-16C, but I'm not the typical hard-core HP calculator user/owner.

I've just acquired my first HP-41, a CV in the box, with almost new & complete documentation (including the registration card, accessories catalog, etc.
The 41 is very clean, not used much, better than very good condition- at least on the outside. The calculator & display look very clean and in great condition too. I'm amazed at such a find for a newbie. There is a bit if dust around the edges of the keypad, how should I clean this?
There doesn't seem to be any gaps along the edges, as would be caused by loose or cracked plastic posts.

I've been going through the manual learning the new machine. This is the most fun part of getting a vintage calc. I just love HPs manuals. They are so well written. I miss the days when you buy a device and actually got paper documentation. I'm all for saving the planet, but good, paper manuals are nice to have.

All keys click like they are new, and the calculator seems to respond to each key press. Many of the math functions are way over my head, so I don't know what to expect for many of them.

That said, I'm familiar with the self tests in the 15C & 16C, and I'm surprised & disappointed that there isn't a self test/acceptance test in the 41, given that it is so much more powerful. Why is that? Did HP run out of code space in the ROMS, or is there another reason?
A built in self test seems like a great idea for every electronic device.

The battery case still holds itself shut, but I think I will buy a spare. It looks like it could come loose if jarred.
There is a tiny bit of corrosion on one of the springs, fortunately it was caught in time before it spread.
The calculator side of the contacts are very bright and shiny, like this one just rolled off of the production line.

I do want to disassemble the whole thing to make sure everything else is ok inside. I'm considering doing the CL upgrade, since the serial number
is in the correct range, and the display has the square corners.

There was a tiny drop of corrosion on the dark padding under the battery case, but it doesn't look like it ran. It's barely noticeable, but I'd liek to remove the residue for the sake of prevention.

What is the best way to clean the corrosion off of the spring and padding? Does vinegar & baking soda remove corrosion?
Is there any compound I should coat the springs with to prevent future corrosion (similar to the lead posts on a car battery)?

Thanks


Tony
cappy2112
...
...
 
Posts: 9
Joined: Tue Dec 06, 2016 5:29 am

Re: First time HP-41 owner needs a little advice

Postby Garth » Tue Dec 06, 2016 6:24 am

Welcome!

cappy2112 wrote:There is a bit if dust around the edges of the keypad, how should I clean this?

Turn it upside down and use a soft brush. The "upside down" part is so the dust you brush away falls away from the keyboard, not into it. The brush will get into the cracks, unlike a rag.

That said, I'm familiar with the self tests in the 15C & 16C, and I'm surprised & disappointed that there isn't a self test/acceptance test in the 41, given that it is so much more powerful. Why is that? Did HP run out of code space in the ROMS, or is there another reason?
A built in self test seems like a great idea for every electronic device.

I think that if there's a problem, it will show up without a self-test, probably by not working at all, which means it could not conduct a self-test anyway. My first programmable was a TI-58c (followed soon after by a TI-59), and it had a self test for each software module IIRC. (These were about 5/8" square, removable, that dropped into the back, and you slide a little door over it.) TI's quality was very poor compared to HP's though. One TI I had wouldn't address the module, which meant it also couldn't run its self-test. A few years after my first TI, I got my HP-41cx.

The battery case still holds itself shut, but I think I will buy a spare. It looks like it could come loose if jarred.

I've had mine for 30 years and never had a problem, although I have dropped it a few times. It won't hold itself shut without batteries in it, but I've never used the calc without batteries. :lol:

There doesn't seem to be any gaps along the edges, as would be caused by loose or cracked plastic posts.
and
I do want to disassemble the whole thing to make sure everything else is ok inside. I'm considering doing the CL upgrade, since the serial number
is in the correct range, and the display has the square corners.

I'd recommend not ever opening it except to do the CL transplant, since opening is apparently the only real cause of cracked posts. My perception (which is no guarantee but probably valid) is that if it's never opened, the posts won't crack. If it works right, it's ok. You don't have to look inside to know that. You won't be able to disassemble the whole thing anyway, because there are heat stakes in it.

There was a tiny drop of corrosion on the dark padding under the battery case, but it doesn't look like it ran. It's barely noticeable, but I'd like to remove the residue for the sake of prevention.

What is the best way to clean the corrosion off of the spring and padding? Does vinegar & baking soda remove corrosion?
Is there any compound I should coat the springs with to prevent future corrosion (similar to the lead posts on a car battery)?

If it's from alkaline batteries, use white vinegar on a Q-tip. I've never had any corrosion in mine, but I've done this trick on bicycle lights and couldn't believe how well it worked! The Q-tip should not be dripping wet. There's no need for that. If the corrosion is from acidic batteries like carbon-zinc or zinc-chloride, then use a baking-soda solution.

The quality of the hardware and the manuals is outstanding. I try to pattern my manual-writing for our aircraft products at work after HP's manuals. This kind of quality is just not found anymore.
http://WilsonMinesCo.com (60 HP-41 links on the links page)
Garth
Moderator
Moderator
 
Posts: 156
Joined: Tue Jan 20, 2009 1:31 am

Re: First time HP-41 owner needs a little advice

Postby leffe » Tue Dec 06, 2016 6:53 am

I completely agree with Garth, dont open the case, it will most probably brake the posts.
The only time my old 41:s have broken is when I tried to reassemble them, and its always the posts cracking.
leffe
....
....
 
Posts: 11
Joined: Sat Nov 08, 2014 8:44 am

Re: First time HP-41 owner needs a little advice

Postby cappy2112 » Tue Dec 06, 2016 7:13 am

Thanks Garth & Leffe!

If it's from alkaline batteries, use white vinegar on a Q-tip. I've never had any corrosion in mine, but I've done this trick on bicycle lights and couldn't believe how well it worked! The Q-tip should not be dripping wet. There's no need for that. If the corrosion is from acidic batteries like carbon-zinc or zinc-chloride, then use a baking-soda solution.

I have no idea which batteries caused the corrosion, they were replaced with new batteries before I received it.
It's a blue-green color, that's the best i can do. I can probably find a replacement spring, or just oder the replacement holder on Ebay.

OK, you've convinced me not to open it up, I'm even sheepish now about doing the CL upgrade.
cappy2112
...
...
 
Posts: 9
Joined: Tue Dec 06, 2016 5:29 am

Re: First time HP-41 owner needs a little advice

Postby cappy2112 » Tue Dec 13, 2016 5:17 am

I think that if there's a problem, it will show up without a self-test


I'd like to revisit your reply about the lack of self test, Garth (and anyone else who wants to jump in).

There must be a better reason, you could also say the same thing about all of the other HP calcs that do have self tests.
cappy2112
...
...
 
Posts: 9
Joined: Tue Dec 06, 2016 5:29 am

Re: First time HP-41 owner needs a little advice

Postby Garth » Tue Dec 13, 2016 8:33 am

Have you ever heard of one of them failing the self test? I'll try to think of all the things I've heard of going wrong with a 41:
  • won't turn on
  • a few keys may need extra pressure to make contact
  • in the card reader, the gummy-wheel problem
  • corroded battery contacts (and again may not turn on)
  • LCD gone bad, either with a portion of the background having turned black or segments that won't go on
  • The only time I heard of an IC going bad was 1985. That was in a coconut (the original 41 version). I've read several times that the halfnuts are more reliable, but I don't know all the categories of reliability that that's talking about.
There won't be things like math functions being off by a little bit and needing re-calibration. I suppose you could write your own self-test program, and test everything you want to. I believe the chain of programs automatically gets tested frequently, and the extended-memory file chain too. When you're new to synthetic programming, it's easy to mess up something there (or also in the registers that HP originally didn't intend for the user to have access to), and instead of trying to piece it back together and make sense of it, the calc just starts fresh and says "Memory lost." It has been almost 30 years since I've seen that message on mine, and it was my own fault. I've had certain often-used programs in mine continuously for over 25 years, never having to reload them.

I used that file chain method in a product I designed at work for private pilots in about 1987. Before it was all debugged, once in a while there was the "Memory lost" message. I was able to go into it and figure out what link or pointer was dangling, figure out what it should be, and correct it and recover the files; but after the software was all debugged, the "Memory lost" message was never seen again. I also had it check all of RAM and ROM upon power-up, but that proved to be pointless. If it was working well enough to get through the self-test, the memory was fine, and if it could report it, the LCD was fine.
http://WilsonMinesCo.com (60 HP-41 links on the links page)
Garth
Moderator
Moderator
 
Posts: 156
Joined: Tue Jan 20, 2009 1:31 am

Re: First time HP-41 owner needs a little advice

Postby cappy2112 » Wed Dec 14, 2016 10:42 pm

Garth wrote:Have you ever heard of one of them failing the self test?

Yes- and those are generally sold for parts at a much lower price.

There won't be things like math functions being off by a little bit and needing re-calibration. [/quote]
No kidding.

You're missing the point completely.
When you buy a calc, the self test would be the quickest way to verify everything works, especially all of the display segments.
I'm not concerned with accuracy of the results, that's HP's responsibility, and any errors would have been documented by now.

The HP42S came after the 41 and it has a self test, although given that it does have as many display digits and segments as the 41, it's
not as much of a problem.

The self test would be a nice convenience to be able to verify functionality when buying one.

My guess is that HP ran out of room in the ROMS or ran out of time getting these shipped (or both).
cappy2112
...
...
 
Posts: 9
Joined: Tue Dec 06, 2016 5:29 am


Return to HP-41 Hardware

Who is online

Users browsing this forum: Google [Bot] and 1 guest

cron