HP-67 Card Reader became very touchy

[Hiwi]

Hi,
there are some cardreaders which write always fine but could not read any cards.
Reading cards shows always ERROR.

Aside from of a high ESR of the capacitors, there could be a problem with the contacts.
Please try to clean the PCB and the contacts carefully.

The older HP67 cardreader PCB had three silver tube tanatalum capacitors, they are high quality and usually never fail. The newer PCB has a different layout with epxoy resin tantalum capacitors.
There are two 22uf across read/write head and one in the supply line, i think it was 22uF too.

I replaced this capacitor in many cases and sucessfully solved the reading problem.

Ralf