hp 82104A only reads 67/97 cards

[Raymond Del Tondo]

(08-29-2016 09:23 AM)John Garza (3665) Wrote:  Yes, I cleaned the head and checked that all the wires were still connected.
UPDATE: I forgot to clean the leaf switches, so I disassembled the unit, and gently ran an alcohol qtip over them for a few passes, then reassembled. Now it doesn't work for any cards! The leaf switches looked perfectly clean and I visually checked their movement (while peering between the card reader frame and their circuit board) with a known good example. Also, I did notice some dry, crumbly, old-dead-drive-roller residue down in the lower circuit card area. Looks too difficult to remove; and since it's rubbery, I assume it's a non-conductor. But could I be wrong?

-John

So it may be a bad contact related to the leaf switches. Check their electrical resistance. I had that phenomen on several card readers. In most cases cleaning them helped, but in some cases I had to replace them by others from another card reader. The failing ones all were in older card readers from 1980 to 1982. Sometimes the bad contact was caused from the PCB side. Similar to the above procedure, on some boards cleaning helped, and some had to be replaced. To be sure: With "leaf switches" you mean the two partly gold-plated metal "leafs" which bow up when a card passes one of the underlying plastic levers.

I also don't know if the roller residue is a non-conductor, however I'd try to remove that stuff, if possible at all.