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mf294-4

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#1
My mill came with a Mitutoyo dro on it. Worked fine for a few years. It now gets decimal points on all of the digits on the X readout. Comes and goes. I can't find any info on it. I would like to get a schematic or some where to send it in for repair. Another idea is to get another readout. I don't know anything about the scales, what kind or if anything will adapt to them. Appreciate any help.
 

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4ssss

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#2
Just Google mitutoyo digital readout and a million things come up
 

kd4gij

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#3
First swap the X&Y cables and see if the problem follows. if it does then it is the scale. If it doesn't then it is the display.
 

Ray C

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#4
If the display has gone bad (which is what I think is wrong), getting it repaired might cost more than replacing it outright.

Ray
 

TonyRV2

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#5
In another lifetime I use to install and service DRO's and CNC controls (Bandit, Sony for you old timers) and I believe what you have there are glass scales given the size. Every once in a while you need to take the cover off and wipe down those scales with some denatured alcohol. The scales are protected, but not sealed, so grit can and does get up in there. That said, the first thing you want to do, as another poster attested, is to swap the cables on the back of your readout. If the problem stays with the same axis, its the readout itself that's giving you the problem, and conversely if the problem changes axis, then the problem is with the scale. Since the trouble that your having is intermittent, I'm first inclined to suspect a poor connection somewhere. These can be difficult to troubleshoot as the poor connection may be something like a solder joint on a circuit board. You may want to just wiggle the cables a bit near the connectors themselves to see if you can force the problem to occur, but without a schematic it would be very difficult to troubleshoot any further unless you have experience with these kinds of things. If you have any other questions about proceeding, give me a shout.
 

mf294-4

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#6
I should have posted, I have switched cables and it stays on the X. I have also opened the display up and messed with the board. I have used freze mist and no change. One time all decimal points are on and now none are on. Earlier this year it would be ok when you initially turned it on then go bad after a few min. Can the scales be used with another display? I have googled it and I can't come up with any useful info. I do have 40 years of electronic experience but not much help without a schematic or any info. I'm thinking bad cap.
 

pacifica

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#7
Possibly your scales are direct plug in to siemens, heidenhain,fanuc or selca( linear scale at402e). I'm suspecting not to less expensive asian nc controllers( 9 pin, DB9 plug).
I was able to fit asian 9 pin scales to an acu-rite controller but had to reconfigure the position of the wires on the DB9 plug to make it work.
 

TonyRV2

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#8
I should have posted, I have switched cables and it stays on the X. I have also opened the display up and messed with the board........
At least you've narrowed it down to a problem with the readout itself on the x axis. I'm not sure, given the age of that DRO if you have discreet chips on your board or if its uP driven. Either way, the electronics basically consist of a counter circuit. At the heart you have an up/down counter and a display driver. The counter's input is a square wave produced by the scales. Since initially the problem would show up within a few minutes of being turned on, I would also suspect a thermal problem. I know you said you used freeze spray on the components, but did you touch individual chips to see if any were running hot? Not all thermal issues can be detected by cooling the chip down with spray. My instinct tells me to look at the display driver. That's where the highest currents exist and that's the chip responsible for driving and selecting the position of the decimal points as well. But your also correct in assuming it could be a support component for that chip as well...like a cap. If you can identify which chip it is, you may want to just go ahead and replace it. Maybe you'll get lucky and its a plug in that you could swap with the Y axis chip. Of course, if the electronics are uP based, there's nothing you're going to be able to do as far as software, but you should still have a display driver in there some place. Hopefully they didn't use proprietary numbers on the chips...I hate it when that happens because it means only the manufacturer knows which chip is which.
 

TonyRV2

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#9
double post
 
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