HP-97 not Charging

[teenix]

The 97 is not guaranteed to work with the charger alone, although it shouldn't cause damage. The printer and card reader definitely won't work. Some 97's may "sort of work" with the charger only if the power supply capacitors are in good working order. Otherwise, the rectified AC from the charger may not be smoothed enough to operate the calculator circuitry.


If that is not the case then...

The battery charge circuit is split between the CPU board and the key/display board. The key/display board seems ok, if a different CPU board makes the charger work.

The charge components on the CPU board are the 4 diodes near the top of the board, and the charger plug. If you have a multimeter you can test the diodes and the connections to the plug.

Another point that may fail and stop the charger is the board to board connector marked in the attached image. This is the connection that transfers the rectified charger voltage to the battery charge circuitry on the key/display board. If this is open circuit, then the battery will not charge.

cheers

Tony