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HP82104A Internal view.

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The card reader consists of three basic parts, the housing, the electronic assembly and the card reader mechanics.

HP82104A

The picture above shows an opened card reader after removing the top of the housing. The PCB on top connects
the switches and photo diode of the mechanical part with the electronics. A photo diode is used, together with a LED to
detect if the card is read only. The mechanical part can be folded to the side to give access to the electronic assembly.

HP82104A

The electronic assembly consists of two small PCBs containing the sense-amplifier, card reader control, motor speed control
and power supply. In the middle the LED for the read only detection is clearly visible. The electronics is build very compact.

HP82104A

The mechanical part takes care of the transportation and reading of the magnetic card. The picture above shows the motor
that transports the card and the backside of the magnetic head that reads or writes the card.

HP82104A   HP82104A

Separating the mechanical unit shows the front side of the magnetic head (picture on the left) and two control switches (picture on the right). The transport wheel is missing in the left picture. These pictures were takes during the epair of this reader.

A deteriorated gummy transport wheel is a common root cause of failing card readers. Luckely, this gummy can be replaced.

HP82104A   HP82104A

The left picture shows the transport wheel with the deteriorated gummy, the right picture the same wheel
with the gummy replaced by two small O-rings.

Repair manuals are given in the links at the bottom of this page.

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HP82104A internal related links:

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