Restored HP-97 Card Reader WRITE ISSUE

[teenix]

The 97 doesn't actually check if data has been successfully written to the card, so it is possible that there is nothing being written, or it is in error.

Yes, the capacitors could be bad, but as it is reading ok, I'm not sure that is the problem. You could try changing them if you wanted. They are 22uF Tantalum types. Make sure they are soldered in the proper polarity as they will be destroyed if soldered back to front.

It seems like you have checked everything, and the voltages to the card reader must be ok for it to read, so I guess the only real way to check is if you have access to an oscilloscope to check that the data appears on the WA WB pins of the sense chip and also that it appears on the magnetic head. Also the WE pin should be about 6V when writing and 0V when reading.

cheers

Tony