HP 41C / issue to turn it on

[Dominique]

Hello,

I just received in France a 41C I just bought from Canada on ebay (really great conditions, no scratches ... like anew one !)... But ...

When pressing ON, nothing happens.
After lots of trials, I finally found a way to turn it on : Master Clear (<-- + ON) several times. It looks strange no ?

Thanks for your help !
Dominique

[rprosperi]

(01-18-2015 04:24 PM)Dominique Wrote:  Hello,

I just received in France a 41C I just bought from Canada on ebay (really great conditions, no scratches ... like anew one !)... But ...

When pressing ON, nothing happens.
After lots of trials, I finally found a way to turn it on : Master Clear (<-- + ON) several times. It looks strange no ?

Thanks for your help !
Dominique

It sounds silly, but make sure all battery contacts are clean. Check all 4 of the spring contacts in the battery holder, plus all 4 of the gold contacts inside the battery bay (carefully). My orginal 41C (purchased early 1980) recently tortured me by refusing to turn-on. Like yours, the reset would sometimes work. After careful cleaning of contacts, all is back to normal.

Note that there has never been a battery leak in this machine, it appears it was just dust, plus age, plus a desire to toy with my emotions.

HTH

[Dave Frederickson]

Cleaners specifically for battery contacts are available, such as DeoxIT for Batteries, which claim to clean and rejuvenate contacts. I can't vouch for the effectiveness of such cleaners, but DeoxIT has a good reputation for contact cleaning products.

[Dominique]

Hi,

Thanks a lot for your replies. My battery bay looks very clean but I cleaned it again. Still same syndrome: need to <-- + ON repeated 3 or 4 times to turn it on.

When turned on I tried some functions like ASN : I've a PACKING message displayed but endless (>30seconds at least before I decided to turn it off).

I also tried to reset it using <-- + ENTER + ON, but Memory lost message do not appears.

I'm currently shortening the battery contacts ... let's see.

My seller told me it worked very well before shipping. Maybe X-rays of airports are badly supported by such old calculators.

Dominique

[Frido Bohn]

To me it sounds to be a more complex issue than just messy contacts of the keyboard. The malfunction may be linked to the infamous zebra-strip contact between keyboard layer and circuit board which is related to the broken-post problem (transport damage?). You may have a quick check if you press firmly on the area between <ON/USER> <PRGM/ALPHA> and the first row of keys while attempting to switch on the calculator as per user manual.
Maybe the problem is even more complex and is related to a damaged circuit board. Radiation at flight checks seems to be a remote cause: consider that the HP41 was used in the Space Shuttle program because its insensibility due to radiation. Consider also that the seller was not that truthful.

Cheers
Frido

[Bruce Larrabee]

I'd like to second the zebra strip hypothesis. There are many different types of zebra strips in the HP41s though. If it is the gold one try very carefully removing it and the plastic frame below it. Clean the strip carefully (It is very fragile).
Also it will often be fixed by sanding 0.010 inches off of the frame. (From 0.060 to 0.050 in thickness.) If it is another type it may need to be replaced.

[Dominique]

I finally decided to open it and to clean all contacts and circuits I could reach.
IT WORKS !!!!

Thanks to all for your support !