Testing the HP65 or HP67 card reader sense amplifier

[albertofenini]

Hi everyone,

Since sometimes the problem with bad card readers could be the amplifier,
we were wondering the following ...

Most of the scopes can generate a waveform,
is it safe to inject that waveform into the input channels of the 1826-0322 or the 1826-0158
and see if the amplifier output RA RB (WA WB also ?) are correct ?

If yes, what kind of waveform should we use, which values and into which pins ?

I know that those chips also provide other functions, but if the motor starts correctly
then checking if the amplifier does amplify should do most of the work, right ?

Also, some of the problems we have experienced where also due to the keyboard assembly,
in that case, other than the traces continuity what could be checked ?

thanks for help and take care !!