[legendarylarry]

I have a PM-940m-cnc-VS with a Delta VFD015E21A inverter drive and 1.5KW 220v 3 phase 1720 rpm motor, Mach3 software on windows 8.1 with a nMotion controller card. The spindle starts and runs fine and will change speeds like it is suppose to when I first power up and run a program or just turn on the spindle from Mach3 for a short time. But once I turn the spindle off, it will never start again. If I power down the machine and restart, it won't work, but if I power down the machine and wait about an hour, it will start up and run fine until I shut off the spindle, then it won't start again. I don't have to reboot the computer or Mach3, just the machine, and wait a while, to get it to start again. I don't have to run it long enough to get it to overheat to have the problem. The VFD led shows the frequency while running, and when I turn the spindle off it reads F4.3, then after a minute or so, will have a countdown to f0.0. But still won't start. There are no fault codes.

This is a new problem for me. I don't really know where to look for the problem. I hope someone can give a little help with this.

[legendarylarry]

One other thing I forgot to mention: When I try to restart the spindle without rebooting the machine, the VFW led show the correct frequency that the motor should be running at. But the motor isn't running.

[ericks]

The first step would be to find out if the issue is with the drive or with whatever gives the drive the start signal

[legendarylarry]

Well, this morning, the spindle wouldn't work at all. I had been thinking the problem would be with the VFD, but I decided to troubleshoot the old fashion way. I got out my meter and followed the leads. The problem turned out to be a bad relay. I can tap on it to make the contacts come together and start the spindle. I had never tried to run the motor ccw, so I tried it. Same problem. Both relays are bad. What are the chances of that. Now I just have to find suitable replacements.

[Bob La Londe]

What are your relays controlling? On my machines relays ONLY trigger the forward and reverse inputs on the VFD.

On some Chinese machines I have I had to replace a couple relays on spindle circuits when they were new or nearly new, but then haven't had any further problems. Just bought plug in replacements off Amazon. I bought extra relays since just about all the relays on those machines were the same. I did have one major issue though. Amazon sent me five relays and a stick. No. I'm not kidding. An actual stick. It had a label on it that said it was a relay, but it was really a bamboo novelty store flute. The kind that's worth about 2 cents and you might find in a junk store for 99 cents. I kindly let Amazon know that calling a stick a relay doesn't make it a relay and they took care of it. I hope the next person is also smart enough to recognze that a stick with a relay sticker on it is still a stick.

[legendarylarry]

You are right that these bad relays only control the forward and reverse. Both are bad so I'm looking for close replacements with the same type rail mount. I hope I don't get any sticks. LOL

[legendarylarry]

The relays that are bad are OMRON MY4N-J. The coil wrapping says 24VDC. The case says 5A 240VAC and 5A 28VDC. It has 14 pins on bottom. Amazon doesn't seem to have them. I haven't found a supplier who has them in stock.

[Bob La Londe]

Digi-Key shows it as a non stocking item.
https://www.digikey.com/product-deta...2ba0b2d8601b5d

Allied shows it as on order.
https://www.alliedelec.com/product/o...kKpg&gclsrc=ds

Search engine results show lots of listings. Might be woth a phone call or two to see if anybody actually has them in stock.


Hmmm... I just searched on Amazon and it shows 1-3 weeks lead time for an Omron at $12: https://www.amazon.com/Omron-MY4N-J-...r=8-1-fkmrnull

It also shows some possible substitutes: https://www.amazon.com/s?k=MY4N-J+re...ref=nb_sb_noss

[legendarylarry]

Thanks. I didn't think about buying a different brand. I ordered 2.

[ericks]

If the problem with the relay is on the contacts then why don't you move over to spare/unused ones...

[legendarylarry]

The relay wouldn't close until I tapped on it. The magnet wouldn't energize. When I tap on it, the Led inside lights up, I hear the click of the relay and the spindle starts. Could be a bad solder joint or short in the windings. But they are cheap, so I'll just toss them and replace them with good ones.

[legendarylarry]

This PM-940m-cnc-VS has an automatic oiler that is driving me crazy. It has a timer set to 30 minutes, and a run time set to 18 seconds. If the machine is powered on it runs, even if I am only setting up or programing. It doesn't need to run so much. Oil is running down the sides of the machine since it runs so much. Every time I power up the machine, I reset the run time to 1 second if I'm not going to cut anything. But the settings won't save. Does anyone know how to get it to save settings?

[ericks]

The relay wouldn't close until I tapped on it. The magnet wouldn't energize. When I tap on it, the Led inside lights up, I hear the click of the relay and the spindle starts. Could be a bad solder joint or short in the windings. But they are cheap, so I'll just toss them and replace them with good ones.

Fair enough.....you should at least test to see if the relay is getting the correct voltage, i have work with those relays for many years and never had a coil failure. Maybe just make sure about the voltage

[ericks]

Relays need more voltage to power up than to be retained. What could happen is your relays aren't getting enough voltage to pull in...when you tap then you basically assist energizing them. Reason i mention this is you have both relay faulty which is not impossible but strange

[legendarylarry]

The voltage to the relay is 23.94V. It has a 24V coil.

[ericks]

The voltage to the relay is 23.94V. It has a 24V coil.

Great

[Bob La Londe]

Its a bad relay. Just replace it with one of the many 24V drop in replacements.

[legendarylarry]

Relays are replaced. Works fine. Thanks.

[Bob La Londe]

I am glad we were able to help. So often I feel like we are shooting in the dark when trying to help somebody.

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FYI: Relays seem to be one of those things that fail in just a couple months or not for a very long time. None of the relays I have replaced on my machines have failed since.