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Mazak AJV-18N spindle drive down

mada87

Aluminum
Joined
Dec 27, 2017
So my AJV-18N went down 2 days ago. I determined that the issue was with the spindle drive. After getting a troubleshooting guide from Mitsubishi, I determined that they issue with that spindle drive power supply had gone out. Yesterday I was able to swap a different power supply and get it running, unfortunately the same thing just happened today. So there is probably something else going on that is causing to power supply to fail but I am not currently getting anywhere with Mits as to how to trouble shoot it any further. Any ideas, thanks!
 
Well any ideas on if I could repair this myself or any reputable companies that rebuild drives. Mits is quoting me almost $6000 to rebuild it or almost $10,000 for a new one, and with it running the machine is hardly worth that.
 
The SF-PW powers the main circuit board, so that’s where I would look next.

First make sure all the pins are making secure contact to the circuit board spring clips. Often these appear to touch and thus transfer current, but you have to double check with a meter! Bend the spring clips tighter and clean for the best contact.

Online or from MEAU, you should be able to get a maintenance manual that shows the pinout voltages for the power supply.

The main circuit board has 12 DK456 hybrid chips, often one or more of those go bad. Also check their related capacitors (probably should change them all), diodes, etc.

There are independent shops that can test/rebuild the spindle drives much cheaper than MEAU.

It’s also a reasonable gamble to buy a complete used drive via EBay, if it was taken out of a running machine.

Good luck with it!
 
The SF-PW powers the main circuit board, so that’s where I would look next.

First make sure all the pins are making secure contact to the circuit board spring clips. Often these appear to touch and thus transfer current, but you have to double check with a meter! Bend the spring clips tighter and clean for the best contact.

Online or from MEAU, you should be able to get a maintenance manual that shows the pinout voltages for the power supply.

The main circuit board has 12 DK456 hybrid chips, often one or more of those go bad. Also check their related capacitors (probably should change them all), diodes, etc.

There are independent shops that can test/rebuild the spindle drives much cheaper than MEAU.

It’s also a reasonable gamble to buy a complete used drive via EBay, if it was taken out of a running machine.

Good luck with it!

Thank you for the input, does MEAU also have info on how to test the DK456 chips? Although I will work on electrical items mechanical issues are much more my gig.

I live close to both First Choice Industrial Services and Nutek sales (part of BTM Industrial) who both sell on ebay so I am always swinging by there places looking for parts, have been fortunate to find what I needed most of the time, but in this case the drives that they have either have a part number missing a digit or 2 or the part number is missing (I need a FR-SF-2-11KP-HBC and they have several FR-SF-2-11KP-C)
 
There was a thread on PM recently on monitoring incoming power:

Oscilloscope and power analyzers?

and older:

https://www.practicalmachinist.com/...aged-machine-servo-drives-253507/#post1892814

Have there been outages in your area? Do you have any incoming power filters (line reactors, etc)?

Perhaps you should talk with your electric supplier to see if there's been issues on their end.

Good idea I hadn't thought about that, I do have 5 other Mazaks that haven't had an issue and haven't gotten any emails from my server that they internet is down (because of loss of power), so I don't think that there has been on outage but maybe could still have been a spike.

No I don't have any incoming power filters, should I? Electrical is not really my thing, I just enough to get myself in trouble.

I did have it on several occasions where they machine would have a fault of insufficient voltage, which in hindsight I had assumed that it was the sign of the power supply going but maybe it was actually an issue with power to the machine or that there was a component in the drive that was drawing too much from the power supply causing the voltage to drop and eventually burning up the power supply?
 
No I don't have any incoming power filters, should I? Electrical is not really my thing, I just enough to get myself in trouble.

I did have it on several occasions where they machine would have a fault of insufficient voltage, which in hindsight I had assumed that it was the sign of the power supply going but maybe it was actually an issue with power to the machine or that there was a component in the drive that was drawing too much from the power supply causing the voltage to drop and eventually burning up the power supply?

There's other people on this forum much more versed in electrical power issues, hopefully one of them will see the thread. If not, do a little reading of the links I sent and look for similar, then when you have some defined questions post a thread in the right subforum, you should get some responses.
 
Alright here is an update on this issue. So I got a replacement drive (used) and it came up and was running. We used the machine for 1 week, it was on but not used at all on Friday or Saturday, I turned it off late afternoon Saturday (I didn't notice any errors but also wasn't really paying attention). Then this past Monday we turned it on and the drive wouldn't come up again. It is again the SF-PW that is out, fuses F1 and F2 were also blown.

It seems that there is likely something outside of the drive that is burning out the power supply. I have gone over this with several techs from Mits and have tested the following items.

spindle motor fan resistance and checked for short to ground
verified that the spindle motor fan spins easily
verified that the connections in the honda connectors is not shorted to ground
verified that the sf-pw is completely gone ( none of the pins read a voltage)
incoming voltage is 480-490
transformer voltage is set to 480 and is outputting 225V
I am getting 225V to the drive as well
this is on a 100amp bus bar with a QT-28 that also has an FR-SF drive and I haven't had any issues with it.
most of the time that the mill is used the lathe isn't running
I have 400 amp service and my other 4 mills (and the lathe) haven't had any power issues


So I am kind of out of ideas, it doesn't seem to be an incoming power issue, the latest idea from Mits is to put another sf-pw in the drive and test out all the components in the drive (and watch for a voltage drop to the sf-pw) but I am hesitant to do that since I keep burning them up.

Thanks
 
225 volts into the drive is actually above the stated tolerance (200V +/- 10%). This could be taxing your power supply.

Try re-setting your incoming transformer to get the power down, if possible.

If you have a little time, you can get SF-PW’s from China on EBay cheap, $300 or so.

There are two cooling fans for the drive that are located behind the power supply. They could be stalled, which will cause issues.

You should be able to see them spinning from the open area behind the spindle drive (they have to have free air), but the drive has to be properly powered up for them to spin, I think.

It is good practice to change the fans out for new ones, just to be safe.

Also, you can slow down your spindle acceleration/deceleration rates, which will greatly increase the life of your drive.

And lastly, your spindle motor windings should be meggered, to see if you have too much resistance from age.

ToolCat
 
225 volts into the drive is actually above the stated tolerance (200V +/- 10%). This could be taxing your power supply.

Try re-setting your incoming transformer to get the power down, if possible.

If you have a little time, you can get SF-PW’s from China on EBay cheap, $300 or so.

There are two cooling fans for the drive that are located behind the power supply. They could be stalled, which will cause issues.

You should be able to see them spinning from the open area behind the spindle drive (they have to have free air), but the drive has to be properly powered up for them to spin, I think.

It is good practice to change the fans out for new ones, just to be safe.

Also, you can slow down your spindle acceleration/deceleration rates, which will greatly increase the life of your drive.

And lastly, your spindle motor windings should be meggered, to see if you have too much resistance from age.

ToolCat


Toolcat

I will look into the 225 volt issue more, the Mits tech that I talked to earlier in the day before my previous post had told me that the machine/control system was rated to 200-230 volts +10%/-15%, which too me seemed like a really big range.

How do you go about slowing down the spindle acceleration/deceleration? I should probably go about doing that on all of my equipment. (everything that I have is mid 1980s to late 1990s)

Should I megger the motor windings to each other, to ground, or to both?

Thanks
mada87
 








 
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