HP32E Hardware Question



#4

I decided to open up my HP32E as after 30+ years it stopped responding to any function key in the third column or any numeric key in the second column while I was using it to test my HP32E simulator. Based upon its age and weight I was expecting it to have the dreaded foam sandwich construction so I'm not exactly surprised that it is finally giving some trouble.

Removing the back cover wasn't too much of a problem though it did require a LOT of force, and I discovered that the top edge of the back of the case is surprisingly sharp. After applying band-aids to two of my fingers I noticed that the middle IC on the left hand side appears to be missing pin 5 (IC is sliver and marked 0031 SGP80008).

Assuming that the missing pin is not the source of the trouble I'd appreciate any useful repair tips. I was planning on just removing the IC carrier and giving all the pins and contact pads a good clean - unfortunately replacing a pin on an IC is well beyond my capabilities!

Although it is the most obvious solution I really don't want to attempt to solder the pins to the circuit board unless I absolutely have to for two reasons - Firstly I killed my original HP33C that way (though at the time I didn't have an anti static mat and didn't realise that the ICs were NMOS), and secondly my electronics tutor used to suggest that I'd be more suited to plumbing than electronics and my soldering hasn't improved since...

Thanks

Mike T.


#5

A missing pin on one of the ROMs in 3xE-series is normal. I have no idea why.

#6

If all the keys of the row or column are involved, the problem would typically be a loss of contact with the cpu keyboard/display connections on pins 21-35.

IMO, soldering them is the best solution, I've done dozens of them without issue. You can fix them without soldering but once they start getting intermittent, them more you fiddle with them, the worse they get.

I would first look at your soldering iron... if it was the typical $10 -$20 class of unit, it's no surprise you killed a calculator with it. No ESD protection nor temperature control.


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