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Help with Mitutoyo electronic digital micrometer

Frank G

Plastic
Joined
Mar 11, 2010
Location
Texas
My first post - I hope it is okay to ask such a complex question for the first one.

I recently bought a Mitutoyo electronic digital micrometer off of eBay (:eek:) and it does not work. It came with a bad battery to begin with. We happened to have a suitable substitute that will power it up, but then it will not work correctly.

When it is powered up, it shows all zeroes on the display with the "in" indicator on and a flashing "P", looks like. This will not change no matter what you do short of taking the battery out. I found somewhere on the Internet where it should auto-shutoff after about 20 minutes. I let it sit for an hour with the display still doing the same thing.

The seller reniged and would not take it back. It was a good price for the instrument which is in very good condition otherwise and the manual measurement works very smoothly.

When trying to find answers on the Internet, I ran across this post which gave me some hope of finding a solution on this forum.

So, am I missing something about the operation of this instrument, or can someone give me advice on how maybe to fix it??? I'm stuck with it so if I can fix it, it would be great.

Mitutoyo 293-765-30 SN 52312xx

It has two buttons on the front: "Origin" and "in/mm". Pressing these in any sequence or combination does nothing. There is no documentation with it.

Purpose is to use it for reloading accurate ammunition. I am not a machinist, but do have an engineering background in electronics and software.

Thanks a lot! :)
 
I actually had a mic do something similar to me and all I did was disassemble and clean up. Apparently when somebody was oiling they went a little crazy and the electronic contacts weren't working properly cause of the oil. Other than that I have not had much luck.
 
Alex, thanks for your reply. Could you go into a little more detail about what you had to clean up with the electrical contacts?

I removed the cover and took a look inside. I did not see any oil right off hand, but realized I probably could not disassemble it without some kind of parts diagram or very specific instructions.
 
Your readout is telling you that you are in inch mode and the preset flashing "P" is waiting for input.

Press and hold the preset button (do not release it) and within 3 seconds you will see the digits in the readout flash, one at a time in 3 second intervals. Eventually it will get back to the "P" and it will flash. At that point release the preset button and press it again. The readout will be at zero if you didn't change anything.

If you released the preset button and pressed it again during the setting cycle the digit will have changed wherever it was when you released it. To correct it you have to run through the cycle again.

These micrometers take a standard 375 watch battery. Walmart has new ones for <$3. -Mike
 
Holescreek, thank you for your response. I had to wonder if there might be some confusion about which model this is, so I am going to post a couple of photos.

4455306601_88dd5efa3d.jpg


4455306737_af8f895b73.jpg


This is exactly how the display looks all the time except I did not catch the flashing "P". I did try doing what you said using each of the buttons, and even both, but I could not get the rolling flashing zeroes. Once, I did get an error-05 when pressing both at the same time. If there is a reset button, I don't know where it is.

If you have any other ideas, I'm interested.

Thanks for your time!
 
Error-05 indicated that the rotary encoder (a round printed circuit board disk) is too far away from the pickup (another round printed circuit board disk). The mic was probably dropped and the disks jarred apart. It isn't a hard problem to fix but it would be hard to explain. It would be easier with an exploded diagram but I won't be back to work for a couple of weeks and that's where the disk is. Micrometers can be very frustrating to adjust. There are set screws under the set screws. Turning the ones you can see won't fix anything, you have to remove them and adjust the ones below then replace the upper screws and hope they don't upset the lower screws when you tighten them down. The disks are held in place by spring pressure and set screws. You have to loosen the screws to allow the spring to push the discs back together then tighten accordingly. Too much spring pressure and the mics are tight in the thimble, too little and you get E05.

Unless you are comfortable working with tiny components you might be ahead sending them out for repair. Unfortunately you have to be vigilant for shops that will tell you it can't be repaired and needs replaced.

By the way, this damage could've easily occurred in shipping from the ebay seller to you.
 
If there is a reset button, I don't know where it is.
There is no "reset" button. That function is accomplished by removing the battery, leaving it out for a period of time (I don't know how long), then re-installing it. I'm sure Mike knows how long to leave it out.

Also, there's no OFF switch, in the sense of turning the mic completely off like a table lamp. It's always on as long as the battery is not dead. The display goes off after ??20?? minutes, but the internal circuitry is still active.

- Leigh
 
Mike, thanks for your response. What you are saying makes sense and the distance between the printed circuit board disks might very well be the problem here. I'm willing to try and fix it myself for the "adventure" (and cost savings) and see what happens. The parts diagram would be a big help, I'm sure. There is no rush, so whenever you get back to work. Should I send you a reminder, since it is a ways out? And thanks for that offer.

Leigh, thanks for clearing up the "reset button"! I would think leaving the battery out for a minute or two would let the capacitors discharge.
 
I have a mic that looks like this one.

I would try turning the thimble in so the faces are touching, then press and hold the origin button untill the display either flashes or shows zero ( I forget which it does).
I think it is telling you it needs to be zeroed.
Could be worth a try 1st.

Regards,
Eric
 
UPDATE...

I would try turning the thimble in so the faces are touching, then press and hold the origin button untill the display either flashes or shows zero ( I forget which it does).
I think it is telling you it needs to be zeroed.
Could be worth a try 1st.

Eric, I thought I had tried this in the past and it did not do anything. I did try again, still with no change in the display. I held it in for several seconds. I appreciate your response.


Here it is. You need to adjust the gap between 19 and 20. 16 and 21 are the double set screws. Good Luck!

1879_001.jpg

Mike, thanks again for posting this parts diagram. It was really handy to have.

I was able to dig into this today, thanks to a rainy day. I pulled off the display and removed set screw 16 and loosened 21. I used a screw driver to try and push part 19 to the right to put the encoder parts closer together. It did not appear or feel like it moved at all. I managed to get the screw 21 back in the groove and the screw 16 back on top of it. Also, I cleaned the electrical contacts on the ribbon cable with pencil eraser. It did look a little more shiney.

After all of this, still no change. Any further ideas? I do not know what constitutes close enough for the encoder and pickup. It looked like only part 19 could be moved, and I could not move it.

It was kind of fun to dig into this, but the scary part is those set screws. Man are they tiny!!!
 
I believe if you can't get it out of "origin" mode (the mode used to set the zero), then that's an electronic problem, not a problem with the disks being too far away. Regardless, you should be able to just press the origin button once (not even a press and hold - just a single press) and the flashing P should go away and the mic should start working.

With this generation of micrometer, it is sometimes difficult to press the buttons. Are you sure you were pressing the button well enough? Try using a small pointer to press the button more positively vs. with your finger.

If it still doesn't work, it might be that the button is bad, or dirty. Not that it helps much because taking it apart and cleaning the button may be a huge pain. But that's what I would look at next.

It looks really clean, so unfortunately I'm not optimistic it's a dirty button. You might need to replace the circuit.
 
That spring #14 can be a PITA sometimes. Did you happen to notice if the circuit disc on 19 was firmly attached? I have seen them where they came loose (they are only glued on).

The good news is that since it didn't work this time, you have nothing to loose by taking it apart and messing with it again. :cheers:
 
With this generation of micrometer, it is sometimes difficult to press the buttons. Are you sure you were pressing the button well enough? Try using a small pointer to press the button more positively vs. with your finger.

Thanks for your response. I've actually been using my fingernail best I could because the button seems to be recessed so as to avoid accidental presses. I did try it with the tip of a retractable pen with no success.

I'll put cleaning the dirty button on the list. Although, as you said, it looks clean and the inside is really clean.
 
That spring #14 can be a PITA sometimes. Did you happen to notice if the circuit disc on 19 was firmly attached? I have seen them where they came loose (they are only glued on).

The good news is that since it didn't work this time, you have nothing to loose by taking it apart and messing with it again. :cheers:

The circuit disc seems to be attached well to 19. The only time it was not turning with the spindle was before I figured out that the set screw needed to be in that groove in the spindle. After I reset the screw, it turned constantly as it should. The actual printed circuit board is somewhat translucent, so you can see the copper pads on the other side well enough to tell it is turning.

Now, spring part 14, how does that play into this? Is it what would push the encoder and pickup closer together? I did not do anything with set screw 16; should I have?

Thanks a lot! Oh, and I did not fasten the display back on, as I'm sure I will be digging into it again! :D
 
Setscrew #16 should have been on top of #21. 21 should only be down into the groove enough to catch the sides of the groove but not enough to lock onto the shaft. 16 screws down on top of it to keep it from turning in or out.

I believe that adjusting the setscrew#16 (to the left of the spring) may allow adjustment of the spacers.
 
Setscrew #16 should have been on top of #21. 21 should only be down into the groove enough to catch the sides of the groove but not enough to lock onto the shaft. 16 screws down on top of it to keep it from turning in or out.

I believe that adjusting the setscrew#16 (to the left of the spring) may allow adjustment of the spacers.

You know, until your message, I did not realize that there were two #16 set screws. I did not touch the 16 screw to the left of the spring. I'll have to do that, too.
 
Hi
Don't get caught out by having fitted a bad replacement battery.
Try a new one from a different source..
Rgds Davycrocket
 
Sounds like on the the buttons has a permanent termination.
Will have to be taken apart. If you attempt it yourself, 2 CAUTIONS.
Be extremely careful not to damage the ribbon cable and use a grounding strap before you touch the circuit board. A reasonable repair can become Expensive fast!!!
Send it to us if you want at Gauge & Measuring Tool Repairs for Brown & Sharpe, Interapid, Compac, Tesa, Mitutoyo, Etalon, Mahr Federal, Starrett & more - Precision Tool Works, Hamilton, Ontario - Gage Repair Services.
Good luck.
 








 
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