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Full Version: How test power supply on dead 33E?
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This is my first post, thanks for letting me join.

I got a non-working HP-33E from a friend. He used it without any battery pack (A/C charger only) for a number of years before the calculator died on him.

Its A/C charger is okay, but the display is black. No cracks are to be seen in the wiring nor in any of the capacitors of the power supply.

Perhaps the next step is to check the outputs of the power supply. Kees Vandersanden (or perhaps it's van der Sanden?) has a schematic on his pages. Any tips on what voltages to expect, and how to test them are greatly appreciated!
The calculator is alive!

The fault was at the small battery compartment board...

... hidden under one of the battery connectors:
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