41CL User Manual
© 2019, Systemyde International Corporation
13
8.
Before removing the old CPU circuit board, carefully inspect all four screw posts on
the front case. If they are cracked or broken (a common problem) they will need to be
repaired before re-assembling the calculator. Instructions for this repair can be found
on the Museum of HP Calculators web site. Repair the screw posts before proceeding
any further.
9.
Using only the edges of the board, carefully lift the old CPU circuit board off of the
base circuit board. The connectors will usually remain in place on the main circuit
board. If by chance they do not, restore them to their proper location. The two halves
of the connector are usually held together by a flexible piece of plastic that fits over
the two screw posts just like the CPU circuit board. Some connectors were held in
place by the black spacer hooking down around the ends of the connectors by about
1cm. This will interfere with several components on the bottom of the 41CL board.
The spacer and connectors should look like those in the photograph below for a
proper installation. If the spacer looks different, trim the excess material so that it
looks like the case shown in the previous photo on the left or the right.
10.
Using only the edges of the 41CL circuit board place this board on the main circuit
board, with the two lower screw posts going through the holes in the 41CL circuit
board just as they did with the original CPU circuit board. Use the antistatic bag
containing the 41CL circuit board to store the old CPU circuit board. Do not throw
away
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want to store the old CPU circuit board, send it to us.
Early versions of the 41C used
nuts screwed onto the posts to hold the CPU board in place. DO NOT use these
nuts without first installing a nylon washer bewteen the 41CL board and each
nut! The nuts are large enough to damage traces on the 41CL board!
If you are
installing the optional serial connector, proceed with the steps below. Otherwise skip
ahead to step 15.