Re: HP25 HOW CAN I TEST IT? Message #2 Posted by Andres C. Rodriguez on 18 July 1999, 8:09 p.m., in response to message #1 by Jorge
All of the following is suggested without any warranty. A possible thing to do is to carefully replace the batteries on the battery pack (I assume you have a battery case, without the batteries) with standard alkaline AA batteries. Be cautious about the polarity ! To power it from an AC adapter, you will need a rather specific connector AND you need rechargeable batteries inside, to act both as a ripple filter and a voltage regulator. If you need other ways, one may be a REGULATED 2.5 Volt DC supply applied directly to the battery contacts on the calculator (check polarity carefully!) or apply a REGULATED 3.2 Volt DC supply on the AC adapter pins at the calculator back. In that last case, polarity should be not a concern, since there is a series diode inside. Last, you may remove the rubber feet, unscrew two screws and access the calculator interior, to power it from an outside source. Good luck, HP25s deserve to live forever!
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