HP34C Repair

[Dieter]

(11-11-2018 03:36 PM)javico Wrote:  What I don't understand is that I've got the HP82090B European charger which says "output 6VAC, 1.3 VA". Sorry for my ignorance, but why am I reading 8.8VAC if the adapter has an output of 6VAC?

The 6 V rating is just a nominal value which is (more or less) the output voltage when the full load of 1,3 VA is applied, i.e. with a current of approx. 220 mA. On the other hand you are measuring the voltage with no load at all, i.e. you get the open circuit voltage. Since this is a very simple AC adapter without any voltage regulation the output is higher than the nominal rating. Only a regulated power supply would deliver the same voltage for any load.

All this also happens with other AC adapters (these are not chargers, the charging circuitry is in the calculator). For instance the 82066A has a nomimal rating of 8 V~ but the open circuit voltage is close to 12 V. That's almost 50% more than the nominal value, just as in your case.

Dieter