HP41C does not turn on

[Jonathan Lenton]

Hi - my son found my 41C and wondered if he could use it. So I bought batteries, installed them and nothing happened, no lights no anything. There was a little corrosion on one of the terminals in the 41C which I flicked off with a pen knife. Is there something else I should do to see if I can get it going?

Note - my son removed the extended functions, quad mem and math module while the unit was turned off. I do not think this should affect the unit actually turning on. Please confirm.

Thanks Jon

[Karl Schneider]

Jonathan --

Check if the connector springs in the battery holder are corroded; if so, clean them in a baking-soda solution.

That assumes it uses disposable batteries. Rechargeable batteries are also used on some units.

[Vieira, Luiz C. (Brazil)]

Hi;

just for checking purposes: can you check if there is any sort of metal available in the batteries connectors? I once had an HP41 in hands with so much oxidation that the metal suface became dust. I had to rebuilt it, and it is time consuming and somewhat risky. Please, verify it when you scraped the oxidation you did not remove the remaining metal contact. It is a golden plated, cooper sheet over a flexible plastic (what makes a flex PCB). Just check it.

Also, removing the modules when the calculator does not turn to ON is harmless. I recommend doing it with the batteries' holder removed, for safety, when the calculator does not lit.

Do you have the skills to open it? If so, let us know. It is not hard to do, just "taking care" is necessary.

Hope you have succcess.

Cheers.

[David Smith]

You will probably need to open up the machine and clean the internal contacts with 91% isopropyl alcohol. This includes the contacts under the CPU board.