bad HP41CX?


I have an HP41CX halfnut that when I put a magnetic card in a card reader, the motor of the card reader doesn´t turn on. Doing CAT 2 shows card reader present, so at least some power is available in slot 4 of the HP41CX. I have put a math module in slot 4 and shows all functions, the module works well. I have checked the card reader in an HP41CV and works perfectly. Maybe this problem should be a bad capacitor of the HP41CX?



Hello, Gonzalo --

One basic thing to check is voltage on each "N" cell (or simply use the battery set from your 41CV. Running the motor to read or write a card requires a certain amount of power that is drawn from the HP-41, and that capability is probably the first to be lost when the battery becomes discharged. (Clock functions are next to go...)

-- KS



I have tested it with a new set of batteries. It seems it doesn´t arrive enough power in the slot 4 toward the card reader



I think there's a hot shoe (unswitched) that's unique to port 4 to run the card reader. It may be bad in your machine.
Best regards, Hal


Which piece is unique to port 4 of the 41CX? I have the schematic of the 41CX and don´t see any difference between port 4 and ports 1-3.


Port 4 has the lines B3 and B4 connected together, it is the only port with that configuration. It is shown on the schematics and is obvious if you examine the port I/O block. I would remove the I/O block and look for battery corrosion, the most likely cause of your problem.

Edited: 10 Dec 2006, 10:51 a.m.


If you clean the contacts of port 4 with isopropilic alcohol you will probably fix it.

Good luck


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