Re: repair of 15C?
Message #1 Posted by Tony Duell on 30 May 2001, 5:38 p.m.
Regarding the construction of Voyagers. I've recently had to take a number apart (for the HPCC club) and all were assembled with the 4 screws under the feet as described
All but one had conventional crosshead screws there, the odd one had Torx (TX6 IIRC) screws. I am not sure why.
The internal construction has changed over the years, though. The early machines (11C and 12C only I think) had a flexible PCB containing the chips (CPU and R2D2) on the back of the display. It connected
to a conventional PCB containing the keyboard switches which is heat-staked to the top case.
This connection is made by one of those conductive rubber 'zebra strip' connectors.
Later 11Cs and 12Cs, and all 15Cs and 16Cs that I've taken apart have everything on one PCB, chips, display, keyboard switches, etc. This PCB is heat staked to the top case. The exact electronic design (how many chips, what they are) has
changed a little too over the years. Early machines have 2 chips, the CPU (a NUT, similar to the one in an HP41) and a chip called R2D2, standing
for ROM/RAM/Display Driver. Later machines may have everything on one chip, the 2 chips just described, or 3 chips (the extra one being more ROM and/or RAM), depending on the machine and version.
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