Spice Calculator - dim display - HP38C

[teenix]

The LED display current comes from the power supply unit.

2 Transistors and 2 resistors form a constant current supply for the cathode driver inside the main CPU IC.

The 16R resistor sets the current so if this has gone higher resistance then the current will reduce.

It may be worth checking these components, but my "stuff" is in boxes at the moment and I'm not sure where on the board they are located.

cheers

Tony