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The mechanics of math: Squeaking case of my to fix?

Posted: Sun Jan 21, 2018 2:51 pm
by mcc

I got a totally alien """problem""" with my DM42:
I opened the case to put a lable, saying that I am the happy owner of this gem, on the back inside of the metal back.
Now after closing the case gently and carefully and fasten the screws gently and carefully I got a """squaeking""" sound
when typing. "Squaeking" is definitely a totally exeggerated term (sorry for my english) but it is in that direction:
A small gab has been built between the edge of the metal case and the plastik frame, which holds the internals of the DM42.

I looesen the screws a little, gently pressed the plastic frame against the metal case and tightend the screws gently again...which
does not work.

Is there any trick of method of handling to get it back in the way it was before I opened it?
Michael? :)

Thanks a lot for any help in advance!


Re: The mechanics of math: Squeaking case of my to fix?

Posted: Sun Jan 21, 2018 4:41 pm
by 4ster
I did the same thing (minus the squeak) when I received my DM42.

I find I often "fix" things by simply taking them apart and putting them back together. If that doesn't fix it :roll: , maybe a little silicone grease in the area you think the sound is coming from would do some good?

Re: The mechanics of math: Squeaking case of my to fix?

Posted: Sun Jan 21, 2018 4:54 pm
by HPMike
I loosened the two outer screws until there was about a 1mm gap between the front housing and the rear cover. This seems to help a lot and also aligns the USB port a lot better with the opening in the housing. The housing does not fit flat against the back, so when you tighten the outer screws, you are actually flexing the housing, which is what I believe is causing the squeeking sound. I only tighten the screws to the point that they are snug and begin to show some resistance.

Re: The mechanics of math: Squeaking case of my to fix?

Posted: Sun Jan 21, 2018 5:27 pm
by grsbanks
When reassembling the unit you obviously start by making sure the bottom part of the case is secure. You sometimes have to wiggle the thing around a bit to make sure that the three lugs on the body of the calculator are properly seated in their respective holes in the stainless steel back.
20180121_171024.jpg (35.53 KiB) Viewed 1813 times

Re: The mechanics of math: Squeaking case of my to fix?

Posted: Sun Jan 21, 2018 5:48 pm
by mcc
Hi all! :)

I found the reason for my """""problem""""": Firmware-updates!



Right after I received my DM42 there were two firmware updates, which I immediately flashed into my DM42 (of course! :)

This bends the the metal of the little USB socket of the DM42 a tiny little bit.
At this point I hadn't opened the case and everything fits well together.

Then I opened the case...lable with my name...bla...close the know.

And The Horrible Squaeking Monsters from Mars begin to invade my Planet DM42.
So I need Plan 9 from outer space... ;)

Open the case.
Closeing the case:
Now - after fitting the noses at the bottom into their holes ( human being can do this... ;) and wiggle them into their places
(THANKS FOR THE PHOTO, GRBANKS!) close the case. When you press down the part of the case, where the holes for the screws are
to close the last mm of the gap take close look at the infrared LED. If it does NOT move, while the frame of the calculator moves,
you are also affected by this problem:
The "lip" of metal part of the tiny usb socket rests on the border of the hole for that usb socket in the metal back and cannot move away from
it. This puts stress on the PCB when tighten the screws.

How to fix that:
Open the case a litte again and press the plastic frame gently towards the noses and while pressing close the case again moving the metal
of the usb socket away from the border. The socket must be completly behind its hole and completly INSIDE the case.
After that the case can be closed without gaps again and especially without bending/stressing the PCB.
At least for me this chases away the squaeking Monsters from Mars.
I hope Plan 9 from Outer Space will work for you too!