Mitutoyo Digital Caliper No Display Repair
A customer brought this Digital Calliper and said it just stop showing the display. He said he replace the battery and still would not come on.
See Name plate of the Calliper below. It is a Mitutoyo CD-12” PSX Model which is a 12” Calliper.
First Thing I did was to open the battery compartment and check the battery voltage and indeed it was reading 1.5 Volts Dc. It was using a LR-44 type battery.
I remove the back-name plate to reveal the 4 Screws the held the front case in place. Upon inspecting the PCB I could not find any damages or bad components. So, I put the PCB under the microscope to see if I could find any problem, When I Zoom in I saw that the traces for the Ground Plane to the battery terminal was corroded and the traces were damage.
With the naked eye, you could not see it. I scraped the PCB and added some Foil tape to the PCB and Soldered it to the battery terminal. See below:
I then clean the PCB and Display terminal with IPA and re-assemble the unit and check the results below:
Mission accomplished. Unit is working fine and measurement are good.
This article was prepared for you by Andre Gopee from Calitech Limited Trinidad West Indies.
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Note: Please check out his previous repair article below:
https://jestineyong.com/china-wireless-remote-control-bulb-socket-repair/
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Robert Calk
October 24, 2017 at 11:45 am
Good job, Andre.
Andre
October 25, 2017 at 2:12 am
The small Square copper piece was soldered across the Scraped ground Trace to Negative battery terminal on both side. I forgot to take a picture of the finish work.
Parasuraman
October 24, 2017 at 11:46 am
Excellent!
Albert van Bemmelen
October 24, 2017 at 5:36 pm
I'm not sure if I understand the explanation seeing the photos and the small copper square piece and the added foil tape that is not visible. But if it works that is all that counts. My TOPcraft Digital Caliper is like your Mitutoyo a very ingenious precision tool I use frequently!
Robert Calk
October 24, 2017 at 11:25 pm
I have a General UltraTech digital calipers that I use a lot, mostly for watchmaking. I have to make some tools in fractions of a millimeter because I can't find them anywhere or they don't exist. Today or tomorrow I'll make a tool similar to a screwdriver but instead will have two opposing tips sticking up. I'll be using bar stock with the OD of 0.70 with tips sticking up on the ends 0.5mm and only 0.05mm wide. It's not going to be easy...
Robert Calk
October 25, 2017 at 1:52 am
Well I decided that it would be easier to modify a sewing needle. So I ground down the end of the eye with my dremmel to give me the tips. I also ground the tip to a sharper point with a lesser angle, and roughed up the middle area to give my fingers better grip surface. Hopefully that will do the job!
Albert
October 25, 2017 at 8:57 pm
I guess you have to mold or mill a metal shaft somehow to shape such a tool? (with OD you mean outside diameter?). Because soldering something so tiny likely will not be possible. I've no idea how you are going to accomplish that Robert. Such precision tools probably already do exist as pro watchmakers tools, so it must be the price tag that prevents you from simply buying these?
Robert Calk
October 25, 2017 at 10:25 pm
Yes, OD = outside diameter. No, the tool does not exist as far as I can tell. I used a sewing needle because I don't have a file small enough to do the job and I don't have a micro-lathe with the milling attachment. Hopefully sometime next year I'll be able to buy a micro-lathe.
Andre
October 25, 2017 at 2:13 am
The small Square copper piece was soldered across the Scraped ground Trace to Negative battery terminal on both side. I forgot to take a picture of the finish work.
Yogesh Panchal
October 27, 2017 at 10:43 pm
Andre Good Job!.
Saroj sae-lim
August 25, 2018 at 4:56 pm
Good jod Thx andre