Need Help!- alarm 55 Z SERVO LAG EXCESS.

[EliseoMonteverd]

Hello, a few days ago I had to replace z axis encoder. Now the machine does not work because It appears alarm 55 Z SERVO LAG EXCESS.

Machine is a 1990 Mazak VQC 15/40 M-32.

What can I do?

Thanks in advance.

[onthebumper]

What was the original problem? Why did you change the encoder? Do you know it is a good encoder? Can you swap the encoder with another axis?

[EliseoMonteverd]

The original problem was an z axis overtravel or something similar, this caused a litle movement in the encoder´s shaft, so as a result, the acrilic disc wich contains the data, had contact with a kind of mirror, and this causes to loose the disc´s data. Yes, it is a good encoder, I have tested in Y axis and works good.

[Leelund]

Coupling broke or loose. Brake not releasing. Screw locked up. Broken or open feedback cable. Maybe bad drive belt if used. Servo drive defective. If alarm comes up at power on, probably servo drive. Start throwing rocks at it!

[onthebumper]

Well let's look at the problem.
1st the alarm means that the motor is not doing what it is being commanded to do.
2nd there are three things that are involved with this
- Drive
- Motor
- Encoder
You have proven that the encoder is fine by swapping with another axis.
Have you tried to swap the drive unit to prove that it is working?
The motor could possibly be defective but not usually in this case.
As Leelund said, the coupling between the Encoder and motor shaft could be broken as well, but if you had swapped this with the other encoder then this should be fine.
You may also have another feedback encoder on the end of the ball screw or driven by a belt as Leelund said. It is doubtful but you could have scales on this machine as well which might cause this alarm.

[EliseoMonteverd]

Well, I have already reviewed everything I could... ultimate was reviewing the own encoder internally. Look at photos and affect the differences in the wiring. What happens if short cables, and again I weld as the position of the previous to make it as the original?, Or could swap the electronic circuit from one to the other?


Links to pictures,

http://www.cnczone.com/gallery/showp...iginal&cat=500

http://www.cnczone.com/gallery/showp...cement&cat=500

[onthebumper]

If the new encoder works on another axis as you have said it does then there should be no reason to change the internal circuitry of the encoder.
The coloring of the wires mean nothing. You must follow the wires to the pins on the cannon connector. Make sure that they go to the same pins on the connector between the two encoders. Again this should not need to be done because the encoder works on another axis.

[EliseoMonteverd]

Originally Posted by onthebumper If the new encoder works on another axis as you have said it does then there should be no reason to change the internal circuitry of the encoder. The coloring of the wires mean nothing. You must follow the wires to the pins on the cannon connector. Make sure that they go to the same pins on the connector between the two encoders. Again this should not need to be done because the encoder works on another axis.

Reviewing the connector, pins are exactly both in the same position, but following the route of the cables, the tip ends at different positions in relation to the electronic circuit.
When I tried to test with this encoder on Y axis seemed not to have problems until I decided to make a change of tools. In short, the pins are not in the same position! The problem in automatic mode is the spindle stops in Y axis around 10 inches before reach the tools change area, I could fix this by making a trick on Y axis parameters, but I don't want to run the risk of a crash without notice.

[onthebumper]

The encoder you are showing is off of the end of the ball screw or on the end of the motor? Have you tried changing the encoder on the end of the motor yet?
What is the model number of the encoder? Is it OSE..... or OAER....?
This will help to determine the pin out of the connector.

[EliseoMonteverd]

Originally Posted by onthebumper The encoder you are showing is off of the end of the ball screw or on the end of the motor? Have you tried changing the encoder on the end of the motor yet? What is the model number of the encoder? Is it OSE..... or OAER....? This will help to determine the pin out of the connector.

The encoder I am showing is off of the end of the ball screw.
...Not yet tried change the encoder on the end of the motor, because the crash was direct on Z axis, and this machine has the motor on the rear spindle column side driven by belt.

IT is an OSE FA CODER TS 5017 N 56 / 5 KN ET 1-3-9.52-0

[onthebumper]

Can you get to the Z axis motor easily?
Can you swap the encoder on the end of the motor?
Are you sure the belt is not slipping?
The encoder on the end of the ball screw is there to make sure the belt does not slip or break. If it does you will get this type of alarm.
I will check to see if I can get you the pinouts of the encoder tomorrow.

[Leelund]

What pinouts are you looking for. The cannon connector to the encoder board?