|An image of an HPIL opened|
Message #12 Posted by Vieira, Luiz C. (Brazil) on 19 June 2003, 1:12 a.m.,
in response to message #11 by David Ramsey
I opened some HP41 ROM and memory modules to try to repair them. In two cases I was successful after re-soldering a couple of terminals. Unfortunately I found at least three ROM modules that did not respond to calculator's commands, and they seemed to be perfectly fine inside.
The best procedure is testing the cables and checking if there's a chance not to open it. Avoid opening the HPIL module.
Look at the picture below. It's an opened HPIL. The original image is from the HP Journal, January 1983, p. 11. Im calling attention to two very sensitive components:
(1) - Hybrid pulse transformer
(2) - HPIL custom chip (for the HP41)
As you can see, both halves are "welded" (ultrasound) together by teir borders. The best way to separate the case is to use a tool that allows you to gently "break" it exactly in the "jointing" surface. This is a time consumming task and there are some actual cases that are easier to open than others (it seems that some modules are better "welded" than others, what is a great disadvantage when opening). I remember seeing some pictures (private page) of one contributor opening a memory module, and he used a small knife. I think you'll have a better idea and you'll probably find your own way to open it; consider doing this only if needed. I did not need to open an HPIL so far, but I'll not hexitate if I need to.
If it does not give you a good idea, let me know. I have a memory module for the HP41 that was opened once. If needed, I'll open it and scan some images showing the process.
Keep in mind that your module may be dammaged or have a broken case if you force it too much or if you use a tool that's sharp enough to destroy the internal components. Please, go slow and take necessary precautions to avoid it.
Luiz C. Vieira - Brazil
Edited: 19 June 2003, 1:22 a.m.