[Markp8153]

When trying to home my MB3 the y axis takes off slamming into the stops. Screen is not counting. Light is on for y axis lmotherboard. Started off by slowly moving when x axis was homing out but now just takes off
at full speed when energized. Where to start? Tach on motor appears good. Need advice please.

[bloke]

Linear scale phuct. Try swapping the X10 cards.

[Markp8153]

Ok. Not sure what x-10 cards are but I did swap x and y motherboard (what was written on the cards) and no difference. The red light stayed on for y axis and acted the same...

[Markp8153]

Bloke put me on the right track. The light bulb, yes bulb not led,was out. I held a flashlight to the reader head after disassembling the scale and the light on the motherboard went out. It's a LS-703 Heidenhain that appears to be the original reader head. Anyone know where to get a bulb? Probably send it out because of alignment issues directing the light focus. AMS in St, Louis knows these older scales and are still repairing them. Hopefully this will resolve the problem. I'll let you know

[Markp8153]

Scale repaired and still acting up. Now goes back and forth on its own as soon as servos are powered up. Screen shows counting taking place but still out of control. What to do next?

[bloke]

Sounds like the phases are swapped on the output of the scale. Does it count in the right direction relative to movement?

[Markp8153]

Hey Bloke, appreciate getting back to me. Actually I'm not sure. Definitely could be as I sent the scale and head out for repair but they ended up replacing entire head. How could I swap to see if that's it? Cable was also replaced and i don't have old parts to see how wires were connected

[bloke]

Can you find the x10 boards in the box that the scale plugs into and take a pic of the inside connections?

[Markp8153]

Hi Bloke, I think there could be two problems. The table moves back and forth back and forth about 5 inches immediately after servos energized without y axis scale connected!

[bloke]

If the count direction is correct, it could be the tach wires have been swapped.

[Markp8153]

Finally got things back to original problem, well sort of.. Swapped wires on y axis tach and darn thing quit running wild. Now the z axis only moves down. Tried to home x and y but y axis came all the way towards me. Perhaps glass reversed since repair as I understand there is some sort of mark etched in scale glass. Not sure tho. How can I check servo amps? Switched them and switched them back but think that may be why z axis not working. I really would like to get this old machine working again and am moving soon...a

[Markp8153]

Getting closer...swapped wires and seems to be it!Now z is acting up.. how can I check servo amps?

[bloke]

Look for the Opto board. Little PCB with 8 pin chips on it (8 chips if I remember correctly). TIL119s.
One of those may be stopping the Z running in one direction.

[Markp8153]

Damn Bloke, you are the best! I've yet to look into your suggestion but you've helped so much along the way. Appreciate all you've done for me and many others..