Mitsu Meldas S03 E42 Alarm

1989 OKK PCV-40 with a Meldas 300m series controller.

The X and Y axis are a shared drive though the issue only seems to be with the X. The machine has done this since I bought it.

I get an alarm 42 on the X axis at full rapids 800ipm, mainly when traveling more than 6-12". As a workaround I slowed the rapids to 600ipm and the accel from 100ms to 180. I would like to crank the rapids back up.

Alarm 42 in not in the manuals for the machine but when searching the internet I find this:

42 FEEDBACK ERROR 1 A skip of the detector feedback signal pulse occurred in the OHE type or OHA type detector
(FE1) used in the semi-closed loop system and ballscrew end closed loop system. A skip of the
SV detector feedback signal pulse in the low speed type serial type absolute position linear scale.

I tried playing around with the max allowable droop parameter and it seems to have little to no effect.

Any suggestions would be helpful. Should I be looking at the drive or the encoder? The machine is currently running parts so I would like to try and get a little better understanding of what's going on before I start swapping around encoders and pulling the drive.

Thanks
Paul

My manual shows this alarm as S01 E42. I have not seen this one happen before. Based on the alarm description and the fact that you can make it go away by slowing the rapid speed, I think it is encoder or encoder cable caused. I'd look at cabling first for a deteriorated wire.

The best method to find bad wires is to test under load. For the typical 22-26AWG wiring used in encoder cables a 2A load and look for voltage drop across the cable is the best test.

Vancbiker said:

My manual shows this alarm as S01 E42. I have not seen this one happen before. Based on the alarm description and the fact that you can make it go away by slowing the rapid speed, I think it is encoder or encoder cable caused. I'd look at cabling first for a deteriorated wire.

The best method to find bad wires is to test under load. For the typical 22-26AWG wiring used in encoder cables a 2A load and look for voltage drop across the cable is the best test.

Click to expand...

Thanks Kevin! I was hoping you would see this.

I included a picture of the alarm so you didn't think I was crazy with the S03 part. I pulled the way cover off and while the Amphenol plug was tight the screws that hold it together were loose as well as the strain relief. I tightened it and was able to restore full rapids and accel. Then while rapiding around a friend jiggled it and it alarmed out so that is likely where the problem is. I took it all apart and the cover off the encoder and it couldn't see anything obvious and it works fine that way.

Ill have to look closer but regardless it appears the general location of the problem has been identified. Might as well blow out the encoder while I'm in there.

Thanks again
Paul

If the Amphenol connector has solder type pins, it would not be a bad idea to re-solder them. I chased an intermittent servo problem on a machine with Mitsu servos and drives and Syntec control that turned out to be cold/poor solder joints at the encoder connector on the motor.

Vancbiker said:

If the Amphenol connector has solder type pins, it would not be a bad idea to re-solder them. I chased an intermittent servo problem on a machine with Mitsu servos and drives and Syntec control that turned out to be cold/poor solder joints at the encoder connector on the motor.

Click to expand...

They are soldered and appeared to be in good condition but I know what you are saying about them being cracked and not being able to see it.

I was able to run nonstop till 10pm last night without any alarms. If it gives me any trouble in the future I'll resolder them and if that doesn't work I'll likely just replace the encoder. I currently have more work than machines and time so hopefully she holds together