Posts: 252
Threads: 14
Joined: Jan 1970
Kevin,
That must be an impressive machine with your dad's name on it :-)
I have to correct you on one point: with HP Classics, if the machine works from the charger but not from batteries, that is NOT an indication that its switching supply failed. The switching supply is used even when you operate the calculator from the charger.
Assuming that the charger itself works (no broken wires), and your battery pack is good, the most likely cause will be those gold contacts that are supposed to connect the two side pins of the charger connector on the back of the calculator. One of these pins goes to the battery pack, the other to the calculator. When the charger is unplugged, the gold contacts connect the two pins, supplying battery power to the calculator. When you plug the charger in, the two circuits are separated; the charger supplies a charging current to the batteries through one pin, and regulated voltage to the calculator through the other.
Viktor
Posts: 149
Threads: 22
Joined: Feb 2009
Kevin,
Check the metal blade in the charging port. When the charger is unplugged the blade should short the two outside posts together. One post connects to the battery and the other to the internal circuits. When you plug in the charger/AC adapter, the batteries are disconnected and the AC adapter supplies power directly to the internal circuits. (The charger also supplies recharging power directly to the batteries, but that's irrelevent here.) It sounds like the blade isn't making a good connection.
The middle post is ground. You can measure the voltage from it to each of the outside post and the blade. You should have the same reading at all three points.
Joe