FR-SE drive board blowing fuses

[Ukraine Train]

I recently purchased a 1986 Mazak lathe. It had a bad spindle motor cooling fan, which was replaced, and it seemed to run fine after that. It sat for about a week and then as soon as I turned on the main switch, two of the glass fuses blew that are on the spindle board. The controller fans and motor fan run off these fuses, as well as other stuff on the board. I tried disconnecting all the fans and the fuses still blow, so it seems like the problem is somewhere in the controller itself. Any suggestions on how to diagnose this? It's a Mitsubishi FR-SE-2-22k controller. The alarm on the screen is 205 motor overload. The hydraulics do not kick on.

 

[amdinc]

Pull off the motor leads and see if it still blows the fuses.

John

 

[Ukraine Train]

Yep, tried that. I need to get some slow blow fuses to try. I believe that's what's supposed to be in there but I didn't have any to try. I'm not optimistic about that, though.

 

[amdinc]

Slow blow fuses will cause other damage to the semiconductor units. A rectifier fuse
will blow in less than one cycle of the ac line a slow blow fuse will take out some other components before it blows.
If the fuses still blow with the motor disconnected you have a short, most likely in one of the power semiconductors.
Short could also be on of the large filter capacitors. Measure the resistance on the output of the unit going to the motor. The three wires should have a high resistance between them. If the resistance is very low between one or all phases you have some bad IGBT s (isolated gate bipolar transistors.)

John

 

[The real Leigh]

It sat for about a week and then as soon as I turned on the main switch, two of the glass fuses blew that are on the spindle board.
The controller fans and motor fan run off these fuses, as well as other stuff on the board.

The "other stuff on the board" are likely powered by one or more AC-to-DC power supplies.
Those consist of a rectifier and filter network, commonly using electrolytic capacitors.

Given that those electrolytics are about 30 years aold, they're undoubtedly bad.
Any competent repair shop can replace them.

- Leigh

 

[Ukraine Train]

I disconnected the UVW leads to the spindle motor and checked resistance in those. I got 2.6ohm between the cables and open to ground. I got more fuses tonight and tomorrow will try to turn it on with the spindle motor disconnected. I'm really hoping it's not that. Any suggestions for a repair place in Northeast Ohio? Seems like the techs I've talked to just swap out components when they're bad; they don't do board-level repairs.

 

[The real Leigh]

they don't do board-level repairs.

Repairing a board to component level is cost prohibitive in the vast majority of cases.

At $150 or more per hour, plus the cost of inventorying replacement parts, a small shop can't stay in business.

There is one place I know of that does such. The tag line on their website says:
"We stock 12,799,385 items from 17,969 manufacturers with a total value exceeding $1,774,720,678"

That ain't a small company. PLC Center MRO Inventory and Industrial Repair Service - PLCCenter.com

Their home page mentions Midwest Industrial Service, Inc, as apparently a recent acquisition.
You might try to contact them directly.

- Leigh

 

[Ukraine Train]

I think I may have traced the problem to the SE-PW power supply. When I disconnected the wires going in, it stopped blowing fuses. I checked resistance across the two white wires and got about 1.5ohm. I then completely removed it from the panel to isolate it from other components, ran 220v directly to it through a fuse and it popped the fuse. Could this be the root cause, or is it possible that the SE-PW went because of some other problem? Would it cause the 205 motor overload alarm? Everything in the SE-PW appears original. It's a Yamabisihi with light blue caps in it.

 

[cnctoolcat]

Yep, the SE-PW's are known to fail. They contain dozens of capacitors, so it's logical after two or three decades the power supply can go bad.
MEAU can rebuild it for you, and they have new ones available too.
Also check EBay.
ToolCat

 

[Ukraine Train]

Coincidentally, I just replaced the SF-PW in my Hitachi mill and the same tech has an SE-PW for me. I'll have it tomorrow morning and will hopefully be back in business.

I also noticed that the voltage coming out of my transformer is 225v so I think I should maybe adjust that down closer to 200v. It's the on-board multi-tap transformer that should be adjustable. There's nothing showing how to set it up behind the panel, though. Is there a procedure somewhere for this?

 

[Ukraine Train]

Well, the new SE-PW did it. The one issue now is when I home the top turret, I get a tail barrier alarm. If I clear it and move the turret off the home position the alarm still comes back on and the turret won't move.

 

[Ukraine Train]

Well, the fun keeps coming. It seemed like all was good after I replaced the SE-PW, but then we programmed a part and started getting a motor overload alarm every time we tried to turn on the spindle. A tech stopped out with a megger and said the resistance in the motor is too low and the motor is shot. Great. Is there any chance he could be mistaken? I don't remember the exact values he got but he said the resistance should be in the mega-ohm region but measured in kil-ohms. It's a Mitsubishi SJ-22A. A rebuilt motor is in the $4000 region or I can get a used one for about $1500 but who knows if it'll just crap out soon too; then there's the possibility of other parts dying. I think I may have an expensive boat anchor at this point.

 

[Bobw]

Well, the fun keeps coming. It seemed like all was good after I replaced the SE-PW, but then we programmed a part and started getting a motor overload alarm every time we tried to turn on the spindle. A tech stopped out with a megger and said the resistance in the motor is too low and the motor is shot. Great. Is there any chance he could be mistaken? I don't remember the exact values he got but he said the resistance should be in the mega-ohm region but measured in kil-ohms. It's a Mitsubishi SJ-22A. A rebuilt motor is in the $4000 region or I can get a used one for about $1500 but who knows if it'll just crap out soon too; then there's the possibility of other parts dying. I think I may have an expensive boat anchor at this point.

I couldn't tell you where what ohms should be... But I do know that every town in America should have a motor rebuild shop or three. We're
talking the spindle motor here, not the spindle. You would be down for a bit longer, but it shouldn't be $4k, shouldn't even be $1500. I
think the most I ever paid was $500 and that was a 3ph 10hp off of a compressor. They rewind them, the whole nine.

Its also just a 3 phase motor of a certain size.. It doesn't need to be replaced with the exact one, or even one of the exact size, or even
the same brand. Obviously some things need to be the same, but its just a motor.

 

[cnctoolcat]

The Mitsubishi spindle motors used on Mazaks rarely fail. Sometimes the PLG unit on the end of the motor will get out of adjustment or it's small board will go bad, but I've never heard of the motor windings themselves going bad.

The most probable cause of your problem is a faulty spindle drive, as they are definitely the most common failure point on an older Mazak. The original bad power supply could have toasted components on the drive's circuit boards, or one or more of the main power transitors in the drive could be bad.

Give Mitsubishi Electric Automation in Chicago a call. They have really good phone support, and should be able to help you out.

ToolCat

 

[Bobw]

The Mitsubishi spindle motors used on Mazaks rarely fail. Sometimes the PLG unit on the end of the motor will get out of adjustment or it's small board will go bad, but I've never heard of the motor windings themselves going bad.

The most probable cause of your problem is a faulty spindle drive, as they are definitely the most common failure point on an older Mazak. The original bad power supply could have toasted components on the drive's circuit boards, or one or more of the main power transitors in the drive could be bad.

Give Mitsubishi Electric Automation in Chicago a call. They have really good phone support, and should be able to help you out.

ToolCat

So it is more than a regular old 3 phase motor? That's no fun.

 

[Ukraine Train]

Yeah, the tech was saying the encoder makes it a specialty job to rebuild. I'll call Mitsubishi. I was about to call them anyway to try to get the multi-tap transformer schematic to bring the voltage down closer to 200v. I'm getting 225V out of it now.

If these motors rarely give out, what would make the resistance read too low?

Another thing I should point out is the cabinet around the motor is quite filthy. There might be an oil leak in there somewhere and it's slinging all over. I'm sure this isn't helping the motor's health.

 

[Philabuster]

Yeah, the tech was saying the encoder makes it a specialty job to rebuild. I'll call Mitsubishi. I was about to call them anyway to try to get the multi-tap transformer schematic to bring the voltage down closer to 200v. I'm getting 225V out of it now.

If these motors rarely give out, what would make the resistance read too low?

Another thing I should point out is the cabinet around the motor is quite filthy. There might be an oil leak in there somewhere and it's slinging all over. I'm sure this isn't helping the motor's health.

The transformer schematic is usually glued to the inside cover of the transformer access panel. There is also a secondary paper copy stuffed inside the transformer usually hidden in a dirty plastic sleeve. High volts (even +10v over nominal) WILL kill a lot of the electrical stuff in this vintage machine. Also, MAKE SURE the incoming power is phased correctly. There is a green LED on the spindle VFD which lights up if phasing is correct. Reverse phasing will cause the DC servo drives to fail in short order.

Screw paying out the ass for spindle motor rebuild. There are always a dozen of them on ebay for the pickins.

Dirty conditions around the spindle motor is a common issue. The machine will function for quite some time even under horrible conditions and then something gives out. That's usually the condition you get it second hand. Spend the time and CLEAN it up and all the numerous cooling fans in the area.

One other thing, turn down the acceleration on the FR-SE. The accel/decel is controlled by a series of DIP switches on the VFD board. Slowing down the accel makes the FR-SE live a LOT longer.

 

[Ukraine Train]

The schematic is MIA; I've looked all over for it. Mazak couldn't help either so Mitsubishi is my next step. I found a used motor right here in town but it doesn't have the flat mounting flange; are these interchangeable? Mine is a frame A160F and the one I found is an A160L but all the other specs match. Or maybe I can transfer the guts into my frame but then I'd need the encoder aligned I think.

 

[Justin_Terry]

Look in electrical prints transformer tap settings should be in there.

 

[Philabuster]

The schematic is MIA; I've looked all over for it.

Try this:

http://www.practicalmachinist.com/v...zak-vqc-20-50b-253050/index3.html#post1947896