Post Reply 
HP 41C Battery Contacts (Cleaning?)
09-23-2014, 01:10 PM
Post: #1
HP 41C Battery Contacts (Cleaning?)
Is there anything I can use to clean off corrosion (or rust?) the golden battery contacts of the HP 41C without having to take the calculator apart?

Thanks in advance,

Eddie
Visit this user's website Find all posts by this user
Quote this message in a reply
09-23-2014, 01:54 PM
Post: #2
RE: HP 41C Battery Contacts (Cleaning?)
(09-23-2014 01:10 PM)Eddie W. Shore Wrote:  Is there anything I can use to clean off corrosion (or rust?) the golden battery contacts of the HP 41C without having to take the calculator apart?

The problem here is taht the copper layer on the flex circuit is quite thin, so there are a lot of chances that it has been completely destroyed by the leak. You can start with a wet cotton to remove any leak rest and then gently polish with metal cleaner. If you find that the copper layer is removed, The Calculator Store has a repair kit that will let your battery contacts as new.
Find all posts by this user
Quote this message in a reply
09-23-2014, 02:45 PM
Post: #3
RE: HP 41C Battery Contacts (Cleaning?)
(09-23-2014 01:54 PM)ElectroDuende Wrote:  
(09-23-2014 01:10 PM)Eddie W. Shore Wrote:  Is there anything I can use to clean off corrosion (or rust?) the golden battery contacts of the HP 41C without having to take the calculator apart?

The problem here is taht the copper layer on the flex circuit is quite thin, so there are a lot of chances that it has been completely destroyed by the leak. You can start with a wet cotton to remove any leak rest and then gently polish with metal cleaner. If you find that the copper layer is removed, The Calculator Store has a repair kit that will let your battery contacts as new.

Regarding the wet cotton, would just water be sufficient?
Visit this user's website Find all posts by this user
Quote this message in a reply
09-23-2014, 03:47 PM
Post: #4
RE: HP 41C Battery Contacts (Cleaning?)
(09-23-2014 02:45 PM)Eddie W. Shore Wrote:  
(09-23-2014 01:54 PM)ElectroDuende Wrote:  The problem here is taht the copper layer on the flex circuit is quite thin, so there are a lot of chances that it has been completely destroyed by the leak. You can start with a wet cotton to remove any leak rest and then gently polish with metal cleaner. If you find that the copper layer is removed, The Calculator Store has a repair kit that will let your battery contacts as new.

Regarding the wet cotton, would just water be sufficient?

As I suppose that the leak came from alkaline batteries, a weak acid will help to remove the remainings; you can use white vinegar, for example. But be sure to remove any remaining, as it will (with time enough) attack the copper.

Wha I usually do when I encounter a device with leaked alkalines is:

- Clean the remainings with vinegar or citric acid
- Rinse with distilled water
- Rinse with alcohol (isopropyl better, but I've also used ethyl)
- Air dry overnigth

To do so I'd recommend you to dissasemble the calculator, so you can rinse the mid module without risking the rest.
Find all posts by this user
Quote this message in a reply
09-23-2014, 09:08 PM
Post: #5
RE: HP 41C Battery Contacts (Cleaning?)
(09-23-2014 01:10 PM)Eddie W. Shore Wrote:  Is there anything I can use to clean off corrosion (or rust?) the golden battery contacts of the HP 41C without having to take the calculator apart?

Thanks in advance,

Eddie

I found I could improve intermittent power outages by gently rubbing the affected terminals with the edge of a piece of card (actually, torn from the blister packet the new batteries came in). This has so far returned the calculator to normal ops (a couple of months, clock still delivering the correct time, no MEMORY LOST messages). I've also been tempted by the availability of a replacement connector flex circuit you can find details of on this forum.
Find all posts by this user
Quote this message in a reply
09-24-2014, 12:33 PM (This post was last modified: 09-24-2014 12:35 PM by Eddie W. Shore.)
Post: #6
RE: HP 41C Battery Contacts (Cleaning?)
The stuff on the contacts is stubborn! Between the white vinegar and the card it seems little has come off. (half an hour)

I am going to rub some alcohol (isopropyl) and let it dry during the day.
Visit this user's website Find all posts by this user
Quote this message in a reply
09-24-2014, 03:54 PM (This post was last modified: 09-24-2014 03:56 PM by jebem.)
Post: #7
RE: HP 41C Battery Contacts (Cleaning?)
(09-24-2014 12:33 PM)Eddie W. Shore Wrote:  The stuff on the contacts is stubborn! Between the white vinegar and the card it seems little has come off. (half an hour)

I am going to rub some alcohol (isopropyl) and let it dry during the day.

Hi, Eddie,

I wish I had a 41C/CV/CX... but it is on my wish list, of course.

As stated above by ElectroDuende, the safest method to a more effective cleaning would be to disassemble the machine.
This is a general rule that I follow for any equipment. The accidental damages will be minimized in this way.

The cleaning procedures you are doing are good enough to remove recent leaking on the outside, but what about the inside? Leaking goes everywhere usually.

For corroded metal I would go for more aggressive measures, and that can only be done by taking the machine apart to work in a safe way.

Jose Mesquita
RadioMuseum.org member

Find all posts by this user
Quote this message in a reply
09-24-2014, 06:51 PM
Post: #8
RE: HP 41C Battery Contacts (Cleaning?)
(09-24-2014 03:54 PM)jebem Wrote:  
(09-24-2014 12:33 PM)Eddie W. Shore Wrote:  The stuff on the contacts is stubborn! Between the white vinegar and the card it seems little has come off. (half an hour)

I am going to rub some alcohol (isopropyl) and let it dry during the day.

The cleaning procedures you are doing are good enough to remove recent leaking on the outside, but what about the inside? Leaking goes everywhere usually.

In my case, I note the corrosion is limited to battery connections 1 and 3 (when viewed from the back of the calc 1-2-3-4). No corrosion on 2 or 4 or on any of the module contacts (which are part of the same flex circuit. See http://www.hpmuseum.org/forum/thread-1889.html for info on obtaining and replacing the flex connector).
Find all posts by this user
Quote this message in a reply
09-27-2014, 06:51 PM
Post: #9
RE: HP 41C Battery Contacts (Cleaning?)
After letting the HP 41C air dry, putting the batteries the HP 41C turns on! Smile

I don't mind the "MEMORY LOST" but getting it to work makes me happy!
Visit this user's website Find all posts by this user
Quote this message in a reply
09-27-2014, 07:03 PM
Post: #10
RE: HP 41C Battery Contacts (Cleaning?)
It does feel good doesn't it. I found, after 7 years of inaction, I could instantly write several simple programs without more than checking the CATALOG. Remarkably different experience from a Prime, so much more expressive programming in a proper rpn.
Find all posts by this user
Quote this message in a reply
09-28-2014, 12:51 AM
Post: #11
RE: HP 41C Battery Contacts (Cleaning?)
(09-27-2014 06:51 PM)Eddie W. Shore Wrote:  After letting the HP 41C air dry, putting the batteries the HP 41C turns on! Smile

I don't mind the "MEMORY LOST" but getting it to work makes me happy!

Congratulations for your success with your 41C!

Jose Mesquita
RadioMuseum.org member

Find all posts by this user
Quote this message in a reply
Post Reply 




User(s) browsing this thread: