HP-65 more on the card reader

[albertofenini]

UPDATE 7/FEB/2019

This is getting intriguing ... so we decided to perform more tests.

We haven't had the time to measures signals at the anode and cathode driver yet, but we will do it in the future.

We did however another test.
Ignazio suggested to investigate, thanks for it, about a possible incompatibility about the two different boards
and the two possible card reader amplifiers : 1826-1058 and 1826-0332.

We performed the first, using keyboard model 000605-60201 rev 3351 B-1341-61 we tested a
card reader with 1826-0332 (originally this unit was completed by a card reader 1826-1058) but we
had exactly the same behavior.

For completeness we will perform soon the opposite test, we will use keyboard 00065-60201 rev 51 803F D 61
and we'll test the two card readers with the two different Amplifiers.

On the other side, what exactly should we measure at the anode driver to see it is noisy ?

Thanks for help to everyone