Re: Most encountered problems on HP97 ? Message #5 Posted by Tony Duell on 23 Nov 2006, 1:29 p.m., in response to message #4 by David Smith
Actually, the topcat series (HP9x) have a circuit which loads the battery line if it tries to reach a higher voltage than the Vss logic supply. You won't damage these machines if you connect them to the AC adapter without a good battery installed, but the printer and card reader (on a 97) will not work properly.
There is an exception to that. The circuit only functions when the machine is turned on. The (very rare) HP95C has the same problems as Woodstock and Spice continuous memory machines in that the RAM supply voltage will go sky-high if the machine is turned off, there's no battery installed, and you connect the AC adapter. This can damage the RAM chips. So if you're lucky enough to have a 95C, I'd charge the batteries in some other machine.
To get back to the original poster's problem, the common failures on the Topcats are the ACT (CPU) chip -- the 22 pin one on the logic board, and ROM0 (the 18 pin chip). The former can be obtained from any Topcat or Woodstock machine apart from an HP27, the latter is specific to the particular type of machine.
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