Repairing a Mitutoyo DRO

1914 people looked at the previous question on this subject, surely someone has an idea.

I'm back fiddling with this Mitutoyo DRO again!

I convinced myself that the fault MUST lie with the cables so I sent them to an electronic repair specialist (www.electronic.partners) for testing and they cannot find anything wrong!

I then decided to have a look at one of the glass scale units which labeled as "AT2-N250" with a Mitutoyo code number of "529-102-5", which I had previously cleaned using optical cleaning wipes.

There appear to be three lights and three 'receivers' for want of a better word, on opposite sides of the glass scale.

Does anyone knew if these are indeed three lights and should they light up when the unit is taken out of the track with the power switched on?

Brian

Does anyone knew if these are indeed three lights and should they light up when the unit is taken out of the track with the power switched on?

Don't know the Mitutoyo scales, but Heidenhain had a couple of systems. The early ones used a 12V filament lamp run at 5V - these could be seen as a dim yellowish glow. Later this was changed to infra red Leds, which could not be seen.

There is a vague possibility that I still have a single axis Mitutoyo readout and scale somewhere in the garage. I rescued it from the skip at my last employment, though cannot recall what it came off & it is possible that I got rid of it. I'll try to have a look over the weekend. I have a similarly vague recollection that it might be a "Magnascale" or something similar rather than an optical scale, though.They are not that popular here - the one I rescued is the only one I have come across.

Nigel B

Assuming that you have more than one glass scale connected to the DRO, could you swap the leads over to find which one is faulty. Or do they all have problems, which is unlikely. If none of them work in any position, then the fault is likely to be in the DRO box.

By 'Lights' do you mean lamps?

If these are incandescent lamps (like torch bulbs) then I would expect them to emit visible radiation, on the other hand if by light you mean LED's then more than likely they would emit infra red and the 'receivers' (photo detectors) would be sensitive to that part of the spectrum, so not visible. One easy way though of checking if IR LED's are working is to view them through a smartphone camera when they would show up as a bright dot.

I am not familiar with Mitutoyo scales but even if you determine that the light source is not working, unless you have reasonable knowledge of electronics its not going to help you find the actual fault.

I have not re-read this whole thread again prior to this reply but is it now clearly established that the whole system works, except for one of the scales?

Ian P

Edit, I see Old Mart too, does not know what area the fault is in

Edited By Ian P on 16/04/2020 21:00:08

Many thanks to all for the replies, I think it may be time to look for a more modern DRO.

Brian

If, as it seems that only one scale is suspect, why aren't you looking at the lights on one that works to see if there is any difference? 

If the lights, or leds are infrared wavelength, they will be invisible to the human eye, but will probably show up if you take a photo of them with a digital camera, or maybe even be visible in "live view".

Edited By old mart on 17/04/2020 16:45:37

To Old Mart, I'm afraid that neither of the scales produce a reading on the display, which could mean that both are faulty or the display is faulty or both are faulty!

Brian

I think your thoughts about a replacement were correct. You could probably get some money back selling the whole lot on ebay. Just sell for spares or repairs giving an honest description, they may be a godsend to someone.

Brian, I like many others on this forum would be very happy to help you get your DRO working, as you say its a long time that it has been out of commission but after just skimming back through the two threads I find that no matter how carefully I try and interpret the results of your investigation, I am still unsure (from your vague terminology) what the situation is!

I am not trying to be disrespectful or argumentative but in order to remotely diagnose where the problem lies a clear and logical approach is essential. Even the description in your last reply conveys nothing that helps, 'neither scale produces a reading' does not say whether the display is even lit up.

I've not looked to see if you give your location but current lockdown rules out physical help but I would be quite happy to assist using Skype/Whatsapp video (PM me for numbers).

Ian P

Thanks for the reply Ian; the basic story is that I bought the mill and saw the 2 axis DRO working. The machine was loaded on a truck and delivered 20 miles to my workshop where it was found that the DRO on one axis had stopped working.

A period of swapping cables to find the cause resulted on the other axis not working. The readout unit still worked and displayed 4 decimal places in Imperial and 3 in metric so, to me, that confirmed that it was working.

I then suspected the cables and sent them to an electronics repair company for testing. The could find no error.

I then had a look at the shorter scale and wondered if there should be lights that shone through the glass scale to what looked like receptors on the other side of the scale but there are no lights. At that point I again appealed for help on the forum.

I have considered sending the whole system to the repair company but the bills are mounting up and I wondered if it was time to cut my losses and look at a replacement.

Brian

Hi Brian have you thought about contacting Mitutoyo ? I did sometime back about a digital micrometer and I found them most helpful

H

Hello Harry, yes I contacted Mitutoyo and they sent me the manual but explained that the unit was no longer supported due to its age, bit like me.

I've persevered with this because of a previous experience with a non-working DRO. This was on a mill that I bought from work because the job it was bought for had finished and the DRO had never worked and was not needed for the job that the mill did.

At work we had an avionics dept so I asked an inspector if he could have a look and 30 minutes later he was back to say he had fixed it by changing a burnt out 3p resistor. Sadly the firm moved to China so I cannot repeat with this 'new' DRO.

Brian

A period of swapping cables to find the cause resulted on the other axis not working.

The trouble with swapping cables around is that you risk doing further damage.

I worked alongside a technician from a major CNC manufacturer on one of my company's installations a few years ago. The intial diagnosis was a failed encoder on one axis - to confirm this, the technician swapped the encoder of the "failed" axis with one of the other axes to see if the fault swapped axes. The result was two failed encoders reported. So he swapped with another axis - result 3 failed encoders reported. At this point I suggested doing checks on the board that the initial failed encoder had been connected to - it was found that the 5V output was actually 12V & every encoder connected to the faulty board had blown due to the overvoltage output.

Nigel B.

Brian they say 'all good things come to an end' maybe the inspector moved so that you could invert in a nice new unit

I fitted a M-Dro package on my lathe couple years back and have been happy with it to date.

H

Got out into the garage this morning & to my suprise found the single axis readout and scale I mentioned. Even more suprising was that when the scale was connected & mains applied it still works - it has been sat up in the garage loft for at least 15 years !

I was also right about it being a "Magnascale", which means that it is a Sony device & not Mitutoyo, so no use for fault finding assistance in this case.

Anybody have a requirement for an apparently functioning single axis readout with a 500 mm travel 0.005 mm resolution scale ? OTOH, maybe it could be used on the wheel downfeed axis of my surface grinder ....

Nigel B.

Thanks for looking Nigel, I imagine it would work well on your surface grinder and you may as well get some use out of it.

Brian

Many thanks to Michael Gilligan for suggesting that I try Goodwin Technology for the repair of my Mitutoyo DRO system.

I got in touch with Darren Goodwin who suggested that I sent the DRO and scales to him for examination and possible repair. He said that the maximum charge for any repair was £125 plus VAT and £15 plus VAT for carriage back to me.

Today my DRO is on its way back to me after being repaired for a total price, inc carriage and VAT of £72.00, which beats the £400 or so that a new system would have cost.

I've not used Goodwin before but they will certainly be top of the list in future.

Brian

That’s very impressive pricing and service, Brian

Thanks for letting us know

MichaelG.

Well done to ParcelPost for returning my Mitutoyo DRO very quickly and even more well done to Goodwin Technology for repairing it.

I've just fitted it back on the machine and it's working beautifully. Now all I need is a job to use it for! I'm doing blacking of steel and assembly work at the moment.

Just for future reference, did they say what the fault was?