HP-65 and HP-67 card reader how to test the amplifier ?

[teenix]

(10-08-2022 07:00 PM)albertofenini Wrote:  Hello everyone,

I have three card readers, all from HP-67 units that apparently don't works

All the CPU boards units when coupled with a working card reader can read and write
which in way proves that the 1820-1751 and the ACT chips work as they should.

All of the card readers have the plug-in connectors rather than the soldered cables,
and I'm thinking of removing these connectors and solder the head and motor cables
to provide a better and more reliable connection

However, prior to do so I was wondering if there is any technique that can help me in
check that the 1826-0322 sense amplifier (BTW all of three have this version) works

Thanks for help and take care

card readers pictures here : HP-65 Card readers

The guess the only practical way is to use an oscilloscope and monitor signals into the IC and signals out at the PCB pins.

Also, use a known working motor for testing and consider replacing the caps.

Soldering the wires directly would be a good thing if you suspect the single connectors are corroded. You may have to trim and strip insulation from the wire ends because new solder may not take to them.

cheers

Tony