[bherr]

Talked with Clarkson in IL and he said a replacement for that encoder isn't available. He stated that its usually not the encoder that goes bad , but a short in the motor. I told him that the motor does move the table, but he said it still could have a short and that would cause the encoder not to count. He did say that the light emitting diode is usually the problem if it is in fact the encoder. Stated that the cost would be somewhere between $302 and $600 for them to fix it.

ben

[bherr]

TTL is 5v and CMOS is 12v typically. By the look of the metal disk, I'd expect just a standard optical pulse encoder, but I trust Al knows them better than I do!

DC

One of many,

found out that it is a ERO 115-125 E8 and yes I do believe its a optical pulse encoder. clarkson wants $300-$600 to repair based on the problem. He said it maybe a short in the motor which would also cause the encoder problem, son't see how, but then he's the expert. Hate to spend that kind of money if its just the optical light emitting diode, which I could replace if I could find the exact match. Oh well, what to do?????????

Ben

[Al_The_Man]

Wow, they look like really old type, very rare you see slotted disk anymore.
I seem to remember going through this before.
The only ERO details I have are for the later glass scale ones, but all optical encoders start out with a sinusoidal signal, if the encoders have an absence of anything in the way of on-board electronics to square up and condition the signal then they are most likely sinusoidal.
George would most likely be able to confirm this.
Al.

[One of Many]

It looks like the light emitting side is under the disk and the sensors are on the board. Not much there for electronics squaring up the signal unless the sensors are optical switches rather than analog.

If you had an IR light source, you could power up the encoder and check if the sensors we ouputing on the scope. All it takes is the loss of the light source or one signal of the pair and it won't count.

DC

[Al_The_Man]

To check the motor, just run the armature leads to a 12v automotive battery.
Did you check the brushes?
Al.

[bherr]

To check the motor, just run the armature leads to a 12v automotive battery.
Did you check the brushes?
Al.

Al,
Motor does work as it will move the table in either direction. I contacted US digital and they need the resolution on the encoder to make a match. How do I tell the resolution? Haven't checked the brushes.

Ben

[One of Many]

Ben, did you find this thread?

On Practical Machinist?

DC

[Al_The_Man]

George maybe able to tell you are you can contact Heidenhain, give them the part number and they should be able to fax you a data sheet.
I am still not convinced it it a TTL or CMOS level output, if not I doubt if US Digital will be able to supply sinusoidal, especially at low signal level.
IOW, Getting one with the same resolution (Counts/rev) will not neccessarlly work if my suspicions are correct.

Replace worn Brushes, $30.00, Replace motor $100's.
Al.

[Al_The_Man]

Ben, did you find this thread?


DC

And I saw that the other day too!
It confirms it is sinusoidal 11µa signal.
So the standard line driver output will not work unfortunately.
Al.

[One of Many]

And I saw that the other day too!
It confirms it is sinusoidal 11µa signal.
So the standard line driver output will not work unfortunately.
Al.

You're encyclopedic Al!

Sounds like a call to Heidenhain in Shaumberg, IL would be my first direction if Clarkson can't supply it. At least Heidenhain could suggest a replacment if there were such an animal.

I had found a couple other threads where the ERO-115-125 is a 125 line encoder.

Here is one

It doesn't say where he got his new light source or go into alignment if you were to get it restored, if that were possibly the only problem.

DC

[bherr]

Guys, I just decided to ship the unit to Clarkson and have them repair it. I can't afford to order something and then find out it doesn't work, so I wasted a lot of time and money. this way I know that they will check everything and repair it to like new condition and warranty it. I want to thank all those who have tried to help as I know it takes time away form what you are doing.

thanks again,

Ben Herr

[gus]

jezuus, don't get carried away, I should have at least one of these on the shelf



light sources usually die, worst case heidenhain can fix it

[bherr]

jezuus, don't get carried away, I should have at least one of these on the shelf



light sources usually die, worst case heidenhain can fix it

Gus,
You find one of these encoders I'm looking for??? I've got the motor packed and scheduled for pickup tomorrow. Need to know! Hate to spend $37.00 + return shipping costs if you have one.

My phone number is 814-243-1673

Ben

[TOTALLYRC]

Hi Gus,
Having been to your shop, all I can say is, only one?

Mike

[gus]

only one...that I am willing to give up..........

[joejared]

Joe,
the motor is a SEM Type MT 30Z4-61
Max RPM =8300
Volts=140
Pulse Amps=50
Tacho= 9.5
Can you explain A vs B as I have no idea what your talking about.
Ben

A and B signals are your descrete position markers.on your encoder

00
01
10
11

The index line, or zero reference, or marker pulse occurs once for every revolution of the motor. It is generally used to refine your homing sequence to the index position of the motor itself, after you've found home with a home switch. You can see it on an oscilloscope once for every rotation of the motor.

Should you install a different encoder and the coordinates are backwards, exchanging the A and A- lines with B and B- will correct the problem.

[Woody111]

If you have not sent this motor out yet I know of a shop in the Pittsburgh PA area that has alot of experience with SEM motors. The are a dedicated servo repair shop and can realign encoders remag motors and they offer a free evaluation. Only cost you shipping. If need a name and phone # contact me at 814 720-5336 leave a message. Woody

[Al_The_Man]

Should you install a different encoder and the coordinates are backwards, exchanging the A and A- lines with B and B- will correct the problem.

Also swapping A and A\ will do it.
Al.

[joejared]

Also swapping A and A will do it.
Al.

True, but don't you also need to swap B and b- as well?

norm = inverted A
A/B A-/B
00 = 10
01 = 11
10 = 00
11 = 01

It appears that the motor will go in the same direction with A inverted.

AB = A-/B-
00 = 11
01 = 10
10 = 01
11 = 00

Both A and B channels need to be flipped, either in using the inverting signals, or by way of exchanging A and B entirely. For non-buffered chips, A and B would need to be swapped, which might lend credibility to being consistent in methods.

[Al_The_Man]

No, done it many times, swapping one changes the phase relation from leading to lagging or vice-versa for a given channel and direction.
Al.