DRO Scale Help

[TweedFab]

I have a Sony LH-10 DRO that I purchased 3 years ago and installed on my bridgeport mill. The DRO was used when I got it and has 3 axis, came with three scales. I used the X, Y scales but did not install the Z (knee) scale. I would swear that I tested it and it worked when I got it, but when I hooked it up the other day it read "error" on the DRO screen.
The DRO scale is part #SR-2711. Can anyone help me diagnose the issue with this scale? I did swap the scale leads on the back of the DRO head to make sure that it was a scale problem, all the other scales read fine if plugged into the Z scale input. Anyone help??
Thanks,
Louis

[BillTodd]

Hi Louis,

I had a similar problem with the magnescale on my lathe. I traced the problem to corrosion in the scale connector.

A chap from AxisUK (Sony's UK dealer) sent me this information:

First check is the reader head in the scale. Remove the underside plate of the scale reader head bracket, 2 posidrive screws, inside there is a small white connector where cable connects to the reader head, if pulled out push back in, if it was already secure disconnect it and remove the cable completely, you may have to ease out the rubber collar. (The connectors and wire connections are more robust than they look) This leaves a small pcb with six solder connections. Turn the pcb over and check if any of the 3 pairs are open circuit. Red to White should be around 1 to 2 ohms Blue to Yellow should be around 12 -15 ohms Orange to blue should be around 12 -15 ohms If any of the above 3 pairs are open circuit the reader head requires replacing which is expensive. If OK check continuity of cable back to the silver plastic connector at the display end, the 9 way D shape connector has a circuit board in it with similar white connector at the scale end, the same 6 colours.

[TweedFab]

Thanks for the cleaning information. I did go through and clean the insides of the reader head and checked all of the connections. I don't know what I cleaned or wiggled the right way, but now the scale is reading. Really hate that when things start working for some unknown reason. Glad to have it working but now I don't know if it is reliable.
Thanks again for the information.

[BillTodd]

Was there any sign of corrosion in the connectors?

Coolant had eaten all the copper out of the wires in my scales.

(see:http://www.mycncuk.com/forums/showth...ull=1#post3198)

[TweedFab]

I could not find any smoking gun. Nothing stood out as an obvious problem. I checked all the wire connections and they seemed to be ok. Checked the continuity of the connections from the solder joints on each side of the connector. My only guess is that in taking it apart and wiping down all the surfaces, and contact cleaning the terminals that it cleaned whatever needed to be cleaned.
Thanks again.