12-14-2017, 01:03 AM
Post: #1
 larthurl Member Posts: 102 Joined: Nov 2017
This is my original HP-41C that I bought in 1980. I used it heavily and then about 1990, it went into storage. I re-discovered it about a decade later and saw that it had battery damage from leaking cells.
Today I decided to open it up and discovered the blue crud. Not sure if cleaning the crud will revive this old friend. It clearly needs a new battery connector.

Any thoughts on how to proceed?

.....Art

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12-14-2017, 05:17 AM
Post: #2
 d b Senior Member Posts: 489 Joined: Dec 2013
I'd soak it in vinegar first to neutralize
the gunk. then rinse it a few times in distilled water and let it dry a few days. An unlit oven warmed with a pilot light or a south facing windowsill in the winter will help that along. Proceed how you see fit once you can tell what your traces look like. I have used a paint-on nickel solution to restore conductivity. A long time member here, Diego Diaz, made some battery blocks and he still might have one. You can PM him.
You'll probably get more complete instructions as people find this and comment. Good luck.
12-14-2017, 11:38 AM
Post: #3
 pier4r Senior Member Posts: 2,109 Joined: Nov 2014
(12-14-2017 01:03 AM)larthurl Wrote:  This is my original HP-41C that I bought in 1980. I used it heavily and then about 1990, it went into storage. I re-discovered it about a decade later and saw that it had battery damage from leaking cells.

This is what I meant when, in the post about "most common calculator", I found really surprising that many old calculators are still in working conditions.

One just need either to put a calculator with batteries for some years in a drawer (because life happens) or a calculator may have difficult to find/adapt battery slots and threfore is not usable anymore.

Wikis are great, Contribute :)
12-14-2017, 11:43 AM (This post was last modified: 12-14-2017 11:44 AM by CY-CL.)
Post: #4
 CY-CL Member Posts: 132 Joined: Jun 2016

ebay - 41C for 100 USD

You can convert it to a CL and you will have the ultimative 41 calculator!
12-14-2017, 12:19 PM
Post: #5
 Massimo Gnerucci Senior Member Posts: 2,474 Joined: Dec 2013
(12-14-2017 11:43 AM)CY-CL Wrote:  Buy a new one for cheap money. Yours is technically dead!

ebay - 41C for 100 USD

You can convert it to a CL and you will have the ultimative 41 calculator!

Then use one of these.

Greetings,
Massimo

-+×÷ ↔ left is right and right is wrong
12-14-2017, 12:28 PM
Post: #6
 Massimo Gnerucci Senior Member Posts: 2,474 Joined: Dec 2013
(12-14-2017 11:38 AM)pier4r Wrote:
(12-14-2017 01:03 AM)larthurl Wrote:  This is my original HP-41C that I bought in 1980. I used it heavily and then about 1990, it went into storage. I re-discovered it about a decade later and saw that it had battery damage from leaking cells.

This is what I meant when, in the post about "most common calculator", I found really surprising that many old calculators are still in working conditions.

One just need either to put a calculator with batteries for some years in a drawer (because life happens) or a calculator may have difficult to find/adapt battery slots and threfore is not usable anymore.

Pier, be aware that the same can happen any day, even on a brand new calculator or whatever device.
A few years ago, @work, I left my wireless mouse on a friday evening, in OFF state. Next monday, when I came back, I found its bottom completely covered by white stuff coming from the battery compartment.

I understand that the more time passes, the greater probabilities are that something like this happens but once we were proud of our calculators and paid an hefty amount to get them so we used and checked them often.
Surely, as reported above, this doesn't shield you from the havoc...

Greetings,
Massimo

-+×÷ ↔ left is right and right is wrong
12-14-2017, 01:47 PM
Post: #7
 pier4r Senior Member Posts: 2,109 Joined: Nov 2014
(12-14-2017 12:28 PM)Massimo Gnerucci Wrote:  A few years ago, @work, I left my wireless mouse on a friday evening, in OFF state. Next monday, when I came back, I found its bottom completely covered by white stuff coming from the battery compartment.

I did not know that batteries can go awry in short time. I thought it happens after they stay there for long time.

Wikis are great, Contribute :)
12-14-2017, 02:05 PM
Post: #8
 Massimo Gnerucci Senior Member Posts: 2,474 Joined: Dec 2013
(12-14-2017 01:47 PM)pier4r Wrote:
(12-14-2017 12:28 PM)Massimo Gnerucci Wrote:  A few years ago, @work, I left my wireless mouse on a friday evening, in OFF state. Next monday, when I came back, I found its bottom completely covered by white stuff coming from the battery compartment.

I did not know that batteries can go awry in short time. I thought it happens after they stay there for long time.

That's what I thought, too...

Greetings,
Massimo

-+×÷ ↔ left is right and right is wrong
12-14-2017, 07:55 PM (This post was last modified: 12-14-2017 07:57 PM by larthurl.)
Post: #9
 larthurl Member Posts: 102 Joined: Nov 2017
(12-14-2017 12:19 PM)Massimo Gnerucci Wrote:
(12-14-2017 11:43 AM)CY-CL Wrote:  Buy a new one for cheap money. Yours is technically dead!

ebay - 41C for 100 USD

You can convert it to a CL and you will have the ultimative 41 calculator!

Then use one of these.

not sure I want to spend $55 on the battery shield if the calc is no good. Same is true for turning it into a super duper 41. I think what I'll try is to clean up the crud then maybe redo some traces (if I can). Attached the correct voltage to the circuit board and if calc is OK, then it may make sense to keep going with replacement parts. One thing I'm not clear about is if I want to conver to a CL, how much of the original circuit boards need to be intact/working? .....Art 12-14-2017, 08:17 PM Post: #10  Massimo Gnerucci Senior Member Posts: 2,474 Joined: Dec 2013 RE: Sad day for HP-41C (12-14-2017 07:55 PM)larthurl Wrote: (12-14-2017 12:19 PM)Massimo Gnerucci Wrote: Then use one of these. not sure I want to spend$55 on the battery shield if the calc is no good.
Same is true for turning it into a super duper 41.

I think what I'll try is to clean up the crud then maybe redo some traces (if I can). Attached the correct voltage to the circuit board and if calc is OK, then it may make sense to keep going with replacement parts.

My advice was to get the battery shield to avoid similar problems in future, not to spend \$55 for it (they are quite rare, however).

(12-14-2017 07:55 PM)larthurl Wrote:  One thing I'm not clear about is if I want to conver to a CL, how much of the original circuit boards need to be intact/working?

Everything but the daughterboard on the bottom side of the calc.

Greetings,
Massimo

-+×÷ ↔ left is right and right is wrong
12-14-2017, 08:19 PM
Post: #11
 hth Senior Member Posts: 413 Joined: Mar 2014
(12-14-2017 07:55 PM)larthurl Wrote:  One thing I'm not clear about is if I want to conver to a CL, how much of the original circuit boards need to be intact/working?
.....Art

You lift out the separate circuit board and replace it with a CL board, the rest of the bits and pieces need to work.

You can check out the details in 41CL Calculator manual

Håkan
12-14-2017, 10:00 PM
Post: #12
 Raymond Del Tondo Member Posts: 288 Joined: Dec 2013
(12-14-2017 12:19 PM)Massimo Gnerucci Wrote:  Then use one of these.
Hi,

I don't recommend the HP battery shield. On the other side of the contact poles, it has relatively sharp edges, so it may actually damage the thin foil of your battery connector.

It was designed that way intentionally, to make sure the contact poles of the shield have contact even with dirty or slightly damaged I/O block connector foils.

-- Ray
12-14-2017, 10:55 PM
Post: #13
 Massimo Gnerucci Senior Member Posts: 2,474 Joined: Dec 2013
(12-14-2017 10:00 PM)Raymond Del Tondo Wrote:
(12-14-2017 12:19 PM)Massimo Gnerucci Wrote:  Then use one of these.
Hi,

I don't recommend the HP battery shield. On the other side of the contact poles, it has relatively sharp edges, so it may actually damage the thin foil of your battery connector.

It was designed that way intentionally, to make sure the contact poles of the shield have contact even with dirty or slightly damaged I/O block connector foils.

Thanks Ray, I dont't own one, so I couldn't know.

Greetings,
Massimo

-+×÷ ↔ left is right and right is wrong
12-15-2017, 08:13 AM
Post: #14
 Jose Gonzalez Divasson Junior Member Posts: 27 Joined: May 2014
Clean it with Caig DeOxit and cotton buds and flat screwdrivers in the worst places. You will be astounded as the crud goes away very easily. I have recovered many units that looked even worse, and now they are CL too.

There are some drop-in solutions for the battery-port module. No assembly required.

You can start with the cleaning and then if you feel confident you can buy the battery-port module.

Best regards,
José
12-15-2017, 12:01 PM
Post: #15
 aj04062 Member Posts: 165 Joined: Dec 2013
An old fashioned pink eraser works great too once the corrosion is cleaned up. You'll need canned air to clean up the mess.

BTW, a pink eraser dipped in alcohol works wonders to clean off marker or paint on calculator bodies.
12-15-2017, 03:36 PM
Post: #16
 larthurl Member Posts: 102 Joined: Nov 2017
(12-15-2017 12:01 PM)aj04062 Wrote:  An old fashioned pink eraser works great too once the corrosion is cleaned up. You'll need canned air to clean up the mess.

BTW, a pink eraser dipped in alcohol works wonders to clean off marker or paint on calculator bodies.

thanks for the pink eraser suggestion.
btw, just saw an HHC video where (I forget who) mentioned that alcohol can erase labels. As he showed.

I was thinking of using Simple Green to clean up keyboards.

.....Art
12-15-2017, 04:19 PM
Post: #17
 Dave Frederickson Senior Member Posts: 2,124 Joined: Dec 2013
(12-15-2017 03:36 PM)larthurl Wrote:  I was thinking of using Simple Green to clean up keyboards.

I've found that Simple Green works wonders on degreasing bike chains, but even diluted I wouldn't use it on a calculator.

Some calc series like the Pioneers clean up nicely using a mild detergent like Dawn and really shine up with Armor All.

Other series, like the Woodstocks, should probably only be cleaned with water else the key legends could be washed off.

Dave
12-15-2017, 04:39 PM
Post: #18
 larthurl Member Posts: 102 Joined: Nov 2017
(12-15-2017 04:19 PM)Dave Frederickson Wrote:
(12-15-2017 03:36 PM)larthurl Wrote:  I was thinking of using Simple Green to clean up keyboards.

I've found that Simple Green works wonders on degreasing bike chains, but even diluted I wouldn't use it on a calculator.

Some calc series like the Pioneers clean up nicely using a mild detergent like Dawn and really shine up with Armor All.

Other series, like the Woodstocks, should probably only be cleaned with water else the key legends could be washed off.

Dave

thank you Dave - the majority of my cleaning projects are the classic series, 41 and some Voyagers.

.....Art
12-15-2017, 10:41 PM
Post: #19
 Benoit Maag Member Posts: 77 Joined: Jan 2014
José,
There seems to be 2 types of deoxit: ‘contact cleaner’ and ‘electronic cleaner’
Which one would you recommend?

(12-15-2017 08:13 AM)Jose Gonzalez Divasson Wrote:  Clean it with Caig DeOxit and cotton buds and flat screwdrivers in the worst places. You will be astounded as the crud goes away very easily. I have recovered many units that looked even worse, and now they are CL too.

There are some drop-in solutions for the battery-port module. No assembly required.

You can start with the cleaning and then if you feel confident you can buy the battery-port module.

Best regards,
José
12-16-2017, 12:09 AM
Post: #20
 Dave Frederickson Senior Member Posts: 2,124 Joined: Dec 2013
(12-15-2017 10:41 PM)Benoit Maag Wrote:  José,
There seems to be 2 types of deoxit: ‘contact cleaner’ and ‘electronic cleaner’
Which one would you recommend?

(12-15-2017 08:13 AM)Jose Gonzalez Divasson Wrote:  Clean it with Caig DeOxit and cotton buds and flat screwdrivers in the worst places. You will be astounded as the crud goes away very easily. I have recovered many units that looked even worse, and now they are CL too.

There are some drop-in solutions for the battery-port module. No assembly required.

You can start with the cleaning and then if you feel confident you can buy the battery-port module.

Best regards,
José

There are more than two types, but the most common are the "D" formulation which is a cleaner that removes corrosion and a "G" formulation that is a contact enhancer and preservative. Both come in 100% and 5% concentrations, in liquid and aerosol. Contrary to popular belief, the "G" formulation is not just for gold. Both formulations work on all kinds of metals.

So what you want is the D100 to remove the blue crud.

Dave
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