Replacing Advanced Motion Controls "brush type 12A8 with "Axcent" amplifier

You could try connecting the encoder to other encoder inputs on the 7i77 to see if you can see any readings from it. Check that the encoder 5v out from the 7i77 is good. Try the encoder only connected to the 7i77 (not also connecting it to the drive).

Try checking the encoder's signal with a volt meter. Just connect the 5v and ground to a 5v source then with the meter probe from the A to ground, while very slowly turning the encoder. You should see some fluctuation of voltage. Then do the same from B to ground.

Todd, Many thanks for your expertise! This is how I used temp wires to use the 5v transformer at (TB1) (unplugged from 7i77 card) to supply 5v to the (TB3) encoder plug (unplugged from 7i77 card) at TB3-3 (GND) to TB3-1 (A) and then a 2nd to TB3-4 (. The 7i77 card & drive were not part of this test. The digital meter ranged from on A=4.74 to 4.80 & B=5.20 TO 5.27, the fluctuation was not dependent on moving the encoder or motor. W/o any motion to motor the meter moved around. When turning motor slowly the meter just did not look to be connected. The meter range was in the 20 range (the other ranges were 2 or 200).

Many thanks, Todd, I am grateful for your help!


(I do not know where the smile face came from)

New card delivery is late Monday (up to 9:00 pm)

Ideally the encoder signal should be either 0v or 5v (and changing from one to the other as you very slowly turn it.)

If the encoder signals don't ever drop below 2v then the 7i77 will not see the transitions.

What is the part number of the replacement encoder?

Todd, many thanks! This was per USDigital recommendation, all the parts:

EM1-2-500-N
www.usdigital.com/products/encoders/incr.../modules/EM1-2-500-N

Todd, I asked the tech at USDigital the question, this is the response:
"The encoder output signal is a digital square wave on both the A and B channels. The high portion of the square wave signal will be near 5V, while the low portion of the square wave will be near 0V (0.5V maximum)."

HUBDISK-2-500-500-NE
encoder wheel:
www.usdigital.com/products/encoders/incr...HUBDISK-2-500-500-NE

CA-LC5-W4-NC-1
Cable&Connector
www.usdigital.com/products/accessories/cables/CA-LC5-W4-NC-1


Many thanks!

I know, but that wasn't what you measured. You said you found between 4.7-5.2, nowhere near the 0v lows. Do you have access to a real oscilloscope and know how to use it? You may need to look at the encoder's output with one. Otherwise double check that you have the encoder correctly installed and wired. It's possible to plug that pigtail in backwards.

Many thanks, Todd. I have found that yes you are correct the encoders were plugged in backward. This did not change what I measured. In addition to en-shore that good connection was being made, put short lead under screw (type of temporary connection), alligator temps to voltmeter, to test today. No, I don't have oscilloscope and know how to use it. In all fairness the volt meter is a cheep one (thinking it may not be quick enough, but with motor shaft stopped, no motion that I can feel, should it read 0.0V at random stopped points), not brand name like central tractor brand.

many thanks

From tracking info this morning, new 7i77 card may be here today!!!!