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Anybody have a service manual for the Acu-Rite III DRO?


Mar 22, 2012
Boston, MA
Just to be clear, I have the users manual already so I don't need that. The Y axis is only showing a single number. The number flickers when the scale is moved, but thats about it. Its not the scale - if I switch axis cables in the back the problem stays the same.
In the users manual, there is a note for "one or several digits or segments do not light up" which recommends "Faulty axis or display board, component level repair or replacement is required".
So... Does anybody have the actual service manuals of this unit? I know it is probably not worth the time to dig into it but the cheap old yankee in me can't resist at least trying to fix something before casting it aside. It will cost me ~$100 worth of connectors and some time to make adapter cables to use the old acu-rite scales with either a Fagor or RSF DRO that I have available, so I feel like it is at least worth an evaluation to see if I can fix the Acu-Rite box.
A service tech told me one time that many of the issues with these can be solved by replacing the filter caps in the power supply. These are thru hole PCBAs so you might consider that as a start.
Thanks for the suggestion. With sort-of limited testing, scales look OK. X-Axis scale works fine on x axis of readout. If i switch the cables so the Y scale is on the X axis of the readout, it also seems to count OK but now the X scale on the Y readout shows the same problem. So the Y readout has the same behaviour no matter what scale is attached.
Havent done further troubleshooting yet, but I'll probably pull out the oscilloscope soon and poke a few things.
The acurite DRO on my lathe had some readout problems, taking it apart,pulling out and re-inserting the ribbon cables solved it, apparently the ends get oxidized and fail to make connection. A newer model than yours.
I've withheld comment until now, but your photo suggests to me a problem with the display driver. The individual LED 'numbers' are multiplexed, sharing time 'on' among all the numbers. The very bright single digit and plus sign may indicate a failure of that row to switch, leaving those elements on full time. The fact that the one digit flickers when you move the axis probably means that the data is getting there, its just not being displayed correctly. In something that old you may be able to identify the display driver IC, and if you're lucky it might even be in a DIP socket. This failure could also be due to a clock issue and that signal could be integral to the driver chip or separate. There are people here (not me) who might be able to identify those chips if you could post good pics showing the numbers.