Issues with magnetic card reader on HP-41CV

[CheshireChris]

I have an HP-41CV in very good condition, so I thought it would be interesting to get a magnetic card reader for it. I bought one sold as "untested" because the seller didn't have a calculator to test it with, but no reason to suppose that it doesn't work.

When I connect my card reader to the calculator, writing seems to work fine. I wrote a short program, went to PRGM mode, put the card in and the motor whirred and I got a message saying something like "RDY 00 of 01". When I come back into normal
Execution mode, though, and feed the card I've just written back through the reader, the first time I do so it says "NO ROOM", and then on subsequent times "CARD ERROR".

Is this the correct way to read in a program from a card? Anything I should be doing differently?

Any suggestions for ways to test the correct operation of the card reader?

All advice very welcome.

[AeeeO]

I have found, that my two card readers work best on the CV and the CX that I operate them with, when no other module is inserted in them and the batteries are fresh. I also have very consistent results with the card readers when I power the 41 from a USB-rechargeable battery pack that I bought from a Dutch seller on eBay.
Still sometimes I have issues reading or writing magnetic cards which I attribute to a slightly flawed module slot due to the age of the machine.

[CheshireChris]

After first leaving sticky goo on the card, it's now stopped feeding entirely and says MALFUNCTION, so I suspect the ancient rubber drive wheels have now disintegrated and require replacing. A job for the future!

[John Garza (3665)]

(08-24-2024 05:19 PM)CheshireChris Wrote:  ...I bought one sold as "untested" because the seller didn't have a calculator to test it with, but no reason to suppose that it doesn't work....

That statement is as wrong as wrong gets.

The card reader components are well past their expected service life.
The proper procedure is to assume it is faulty unless the device has been serviced recently.

-J

[rprosperi]

To add context to John's message, essentially 100% of 41 card readers have had their 'rubber' rollers erode and 'melt' into goo by this time. A handful of 41 card readers (3-4?) have been claimed to still be working w/o ever having the rollers changed, but if true, these are very rare anomalies and probably result from the readers being stored in some atypical conditions (especially dry? or cool? or... who knows?).

In addition to the roller material failing, there is motor shaft coupler (often called a clutch, which it isn't) which also fails in nearly as high a percentage of units, so when the rollers are changed, this coupler should be replaced as well; there are lots of articles, videos, step-by-step guides, etc. here on how to do these repairs DIY-style, and there are also members here, on eBay and on FB that will do this service for a fee.