The Museum of HP Calculators

HP Forum Archive 06

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Re: HP-33E Parts
Message #1 Posted by Tony Duell (UK) on 11 Sept 2001, 3:08 p.m.

No problem with the advice, I am pleased it's all working now. The 33E is a fairly nice machine... Are you saying there are 2 versions of the 33E, with incompatible PSU boards? I can well believe it, because later versions of the -E models have the same keyboard/logic PCB as the -C models. There's a separate power supply line to the rearmost memory chip, which is the battery-backed RAM (at least in part) in the -C models. On the -E models, this line is connected to the main supply line on the PSU board, while on -C models it's battery backed as well. Possibly there was an older version (before any -C models were made) whereall the memory chips have the same supply line and there is no provision for battery backing them. That could mean a different PSU board.

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