[cnc1000]

Everything was operating just fine and then all of a sudden, the Y-axis ran to the limit and jammed. Happens every time it's turned on. It's like a resolver or something broke and it has no idea where it is and decides to just run as fast as it can to one end. Is this problem typical of some common cause? Anyone know where to look? This is my first post. Just joined, today. Thanks. Jim

[cncven]

What model of control do you have in your machine?
What model of drivers?

Can you check the encoders?

the cause of your problems could be in the signals cables or the encoders.

But I need to know what control do you have.

Regards CNCVEN

[cnc1000]

I think it is Faunc controls, but I'll check to be sure. I was suspicious that the cables that keep getting jiggled around as the stage moves, were to blame. I'll report back. Thanks.

[cnc1000]

The controls on this Cincinnati are Acramatic 900 V2, it turns out. We're just stumped on why it jams the Y axis. How do you get into the area where the encoders and wires are located? Many thanks. Jim

[cnc1000]

This Cincinnati Acramatic 900 uses resolvers instead of encoders, I found out. Does that help isolate the problem? Thanks.

[cncven]

This control were the first control of Cincinnati Milacron that used encoders.

Let me find for you the pin schematics for each encoders.

Maybe you have a wire broke.
CNCVEN

[underthetire]

If they are DC motors, they may have a tach generator. If a tach generator or cable to it broke you will get a run away.

[cnc1000]

How can I tell if it is a resolver, tach, or encoder? I'll try to figure out how to access both ends of the wire. Maybe open up the encoder area for starters...
Thanks.

[mtcnc]

What make of motor is on the machine. The A900 uses Resolvers or Farrand Scales feedback not encoders.

[cnc1000]

I don't know, but I'll look and see what the motors are for X, Y, and Z axis and get back to you. Thanks very much for the help. We still don't have this machine up and running.

[cnc1000]

I think I found the resolvers. There is a module on the lower back area that looks like it has a small motor inside, plus a large motor, which may actually be a resolver, for all I know. It's about a foot off the ground. A cable runs to it with oh, 6 or 7 leads. Is this the resolver for the Y axis? Wires look ok but I'll go over them carefully. Any help is greatly appreciated. Jim

[mike_Kilroy]

couple comments/ideas, You HAVE to write down the motor part numbers for us - you HAVE too for proper help! I assume from the 900 cnc and the 5vc part no this is a 1985 or so machine?? CMI did not use Fanuc until well later in life. They are most likely my Inland motors (also known as Industrial drives, Kollmorgen, Danaher) or Gettys. if Inland, we often sold TT4020 & TT-5301 models; if Gettys they were mostly size 20 & size 30 models. Both had integral tachs, most also had the position loop resolver inside the back endbell of the motor too - unless ferrand/scales were used. Not often but sometimes the posotion resolver was put on the opposite side of the ballscrew than the motor side. They will most likely be Dc brush motors so they DO have tachs inside each motor (for the servo drive) and also a resolver for the 900 cnc. If the resolver has a problem the 900 cnc should be smart enough to shut off on excess position error so not too likely to run away as you describe. If the TACH inside the motor is bad (and they are a wear item) then the axis of that generation WILL most likely run away. So I would spend more time on tacing the TACH wiring than the resolver. You cannot tell from the 900 cnc screen if the tach or its wiring is bad, but you sure can if the resolver is bad. I would not go taking any resolver stuff apart before looking at the 900 cnc screen! have someone move the motor while you watch the position feedback line - if it moves and reads right, your resolver is fine dont mess with it. If it does not move, try another axis that does work and verify you see position display move so you know you are not looking at the wrong thing. If other axes move but Y does not, then yes your position resolver has issue.

WRITE DOWN THE MOTOR PART NUMBERS FOR US!

[cnc1000]

Hi, Mike.

Ok. I'll get in there and start writing down numbers. Yes, this is a 1980's machine, as best I know. I'll get some pictures, as well. What I think I'm seeing is a DC motor with a large commutator and a couple of brushes. Right next to it is what looks like a small motor, but could well be a resolver. It is tight up next to the motor, about an inch in diameter and 3 inches long.

I'll get it running so I can read the screen, but we have to do the paper tape boot-up process because it sat unplugged for a long time and lost it's brains.

This is really good info, Mike. You obviously know your stuff. So, are the tachs something I can purchase or can they be repaired? What is the rough cost of a tach? This machine was working perfectly before the y axis just ran away, all of a sudden.

Thanks very much for your help.

Jim

[Al_The_Man]

. So, are the tachs something I can purchase or can they be repaired? What is the rough cost of a tach? This machine was working perfectly before the y axis just ran away, all of a sudden.

Jim

I agree with the others, it sounds like tach, or at least check this first, it is a two wire device that looks like a small dc motor on the rear motor shaft.
The resolver has 6 wires, or 7 counting the shield.
The tach can be spun and measure for DC voltage output + or - depending on direction.
In cases where originals are no longer available/expensive/hard to get, I have adapted ones made by Servo-Tek
http://www.servo-tek.com/
Al.

[cnc1000]

Boy, this is getting close! Wish I had some pictures and numbers right now. I'll get them tomorrow and look at the tach. I think the tach must be the one where it looks like a huge commutator with two small, spindly brushes on it. I'd guess the commutator was 2 inches in diameter. What part of the tach fails? Dirty brushes? Is it essentially a dc motor where you see the pulsations as it rotates, and different coils roll past the magnetic fields of a permanent stator magnet? I saw some non-factory soldering in there. Maybe a connection gave up. Why would there be a need for a tach, when there is a resolver there? Just redundant systems?

Thanks, guys! I'm excited to get it fired up.

Jim

[mike_Kilroy]

lots of question! As Al said, even obsolete tachs are available with replacements like his suggested servo tek ones.....

If it is one of my old Inland motors, we actually stock replacements for most of these! Yes, your description sounds like a tach. In most of that vintage Inland motors we used TGF2168-A part number tachs our own model and design). If it is a Gettys motor, they actually bought ServoTek size 11 tachs - that as Al said are still available too. New tach is ball park $ 300-400...... Lots of times you can clean the commutator with like #800 sand paper.... We used to sell replacement tach brushes but stopped about 10 years ago - sell whole tach replacement now....

why both tach and resolver? technology of the 1980s was we needed analog velocity loops; resolvers have to be converted to digital sig then back to analog and this was way to slow to make a good velocity loop controller. so we needed both. enter higher power computers and today we use a digital feedback thing and convert their sigs to tach sigs too and get away with it. We probably sell 70% of our servos still with resolvers instead of encoders due to old machine tool belief that they are more rugged than encoders. not really true but lots of people still like ruggedness of resolvers.... sorry for talking to much! get us part numbers!

[cnc1000]

I have some numbers, now. It's definitely an Acramat 900. The documentation I have was written in 1982. There is a tach and a resolver in a box on the lower rear area. Picture attached.

The tach is Siemens
Type 1HU 1052-2
20V BEI 1000/min
Load 13.3 k ohm

The resolver says:
Siemens V23401-E2002-B104
12/6V 2500 Hz
SCHLEIFRINGLOS

The junction box where the tach output comes out had some metal chips in it (big help, eh?) and I cleaned the commutator with 1200 grit sandpaper and put an oscilloscope on the two leads and turned the shaft. I got a square wave output, so I think that works. Maybe the sanding made it work and maybe the chips was making it not work. Don't know.

New problem: When I set the cover plate to the side to look inside, it fell to the ground and all 6 wires from the resolver broke off of the connector. I don't know the color codes so I can't hook it back up. I have a schematic that shows what pins the sine and cosine go to, but no color codes, so I'm screwed until I find the colors out.

Once I can hook the resolver back up, I will try to fire it up and probably need to reboot it with the paper tape reader. Anyone know the colors on that resolver? Thanks much! Jim

[mike_Kilroy]

ouch!

So we still don't know what motor part numbers are - are you getting those for us?

As for your tach, it is nice that you have a nice square wave that is pretty, but unfortunately that is a bad tach signal! It needs to be a nice flat line with no shakes, no ups or downs.... Sorry. So you have a bad tach if you read the scope correctly. I assume the square wave is due to a burned out tach coil - ie., as the brushes go around the commutator hooking different coils up as it turns, it is going across a coil that is burned open; hence the output voltage goes down to 0 during that commutator section. You can verify this maybe by just ohming across the 2 tach wires while you slowly turn the tach; it is likely around 20 ohms? everywhere except on the burned out coil where it will go to open.

As for the Siemens resolver, I have probably color code and wiring pin out, along with the specs on that tach part number but I do not know how to attach a small pdf doc to this message. So email me private message (I think click on my name and it will give that option) and I will email you the doc.

[Al_The_Man]

It also looks like a Siemens motor to me?

but I do not know how to attach a small pdf doc to this message.

Mike, When posting a message, go down to 'Advanced' and the file upload screen will appear.
Al.

[mike_Kilroy]

Thanks AL. here is doc

small pdf (150k) with info on both tach and resolver