HP 65 Card reader task

[teenix]

Sorry, I missed adding the voltage on pin 17, see below.

The power supply voltage is probably dropping a bit because it may not be able to supply the calculators operating current, especially if it drops when the motor is trying to turn on. Most power supplies should be able to cope though.

Anyway, assuming the calculator is just turned on in run mode, (these voltages may vary a bit),

Pin 17 [MOTOR CONTROL] should be 6V.
Pin 1 [MOTOR VOLT] should be 0V.
Pin 11 [WE] can be either 6V or 0V it doesn't matter.
Pin 16 and 18 should be the battery voltage
The rest of the voltages should be as marked.

As soon as you push a card in with the Run/Prgm switch in the Run position (card read):

Pin 17 [MOTOR CONTROL] should fall to 0V. <<<<Make sure this drops to 0V
Pin 1 [MOTOR VOLT] should rise to 2.4V.
Pin 11 [WE] should be 0V for a read operation
Pin 16 and 18 should be the battery voltage
The rest of the voltages should be as marked.

Hybrid IC
pin 1 same as [WE] voltage
pin 5 same as [MOTOR CONTROL] <<<<Make sure this happens

If the [MOTOR CONTROL] does not drop to 0V check the voltage on pin 9 of the connector at the bottom of the calculator. It is the same connection, and it should also drop to 0V. If it does not, the hybrid and sense IC's are not seeing the card switch activating.

cheers

Tony