Panasonic Minas A1 servo drives - Page 1
Forum section: electronics / projects

author: Norbert67
author_rank: Contributor
timestamp: March 24, 2022, 10:32:00 am
content: Hello.Years back I decided to build a smaller cnc machine, but at that time without much experience with servo drives I couldn´t test them properly. Of course when the whole machine was put together, I realized that some of my motors and controllers were not working as intended. These are Panasonic Minas A1 series servo drives. 1x400W, 2x750W and one 1kW.The only thing I have found about these is a operating manual. I would like to ask You guys, if anyone of You have met with a service manual or schematic for these drives. I have a feeling that the encoders on some of the motors are also misalligned, so thats another question: how were these optical encoder alligned?

author: thm_w
author_rank: Super Contributor
timestamp: March 24, 2022, 10:31:12 pm
content: Might belong in the repair section:https://www.eevblog.com/forum/repair/Do you have the cable to connect the controller to a PC?https://industrial.panasonic.com/content/data/MT/PDF/minas_a_e.pdfThe software I see online says for A5 and A6 only, but might be worth a tryhttps://www3.panasonic.biz/ac/e/motor/fa-motor/ac-servo/panaterm/setup.jspWith some of these servos the software is absolutely essential as you have to program the drives to match the motors, and match the inputs you are giving them (ie CPR, step/dir input, differential, etc.)Why would the encoders be misaligned unless someone has taken them apart?

author: Norbert67
author_rank: Contributor
timestamp: March 25, 2022, 02:21:28 pm
content: Yes i have the original program and cable too. The parameters are set. Some of the drives are used and I see marks on the shaft that means somebody manipulated with the encoder. I can change the 750w drives and the motors between them and I have a drive that is problematic and one of my motor also has something to it.I know that the problem with the drive with the upper board but dont have any schematic.

author: thm_w
author_rank: Super Contributor
timestamp: March 25, 2022, 09:59:29 pm
content: Photos might help.Is it obvious where the encoder was originally installed? Can you try moving it back to that position and powering it up again.Are there hall sensors as well?Usually they will just rely on the hall sensors for driving the motor, and encoder for fine positioning. So if the encoder was moved it shouldn't affect the function at all. But maybe the person that moved it was trying to resolve a different problem.For the drive you'll have to compare working and non-working units and see if you can narrow down what is causing the issue.Does the original program report any drive errors?

author: Norbert67
author_rank: Contributor
timestamp: April 12, 2022, 05:54:53 pm
content: Hello. Sorry for the late reply.Yes I tried to set the encoder back to its place, but it doesnt work any better. As for the encoder, they dont have hall sensors. Its an optical encoder with a diode and a photo-sensor or transistor on the other side. The glass in between has markings and these 3 symmetrical outputs are provided as feedback for the servo drives plus a digital signal of some sort.I have a damaged one on my desk so I can take some pictures.As for the drives: I changed the upper boards in between the same types, and I know that one of the upper boards has some failure, but without any schematic its like looking for a needle in a haystack.The symptoms of my bad ones are:The motor tries to rotate but the shaft doesnt move, the noise is getting louder then after a specific amount of steps the drive shuts off the servo-on signal and displays an error. Most of the times the error is a position error but sometimes its overtorque - so because both of these are calculated from the position which is provided by the encoder, I think the problem will be there.

author: thm_w
author_rank: Super Contributor
timestamp: April 13, 2022, 10:56:51 pm
content: You can try to figure out where to power the encoder, and what voltage to apply, and test it on the bench. In the manual they list 5V with A/B/Z outputs. Hopefully those would work as-is.You can get cheap generic encoders, but, the problem here is it looks like they are also using a serial communication connection. So there will be no easy way to have the original drive working with a generic encoder, which means you'd need a new encoder and drive as well.Genuine replacement encoders seem to be quite expensive.Could sell what you know works, use the remaining money to buy known good parts.