Power supply died on Mini Mill

[PBMW]

Looks like my powersupply has died. Monday it started turning itself off randomly, couple times. As the week went on it would happen more and more often. Won't turn on now. Called Haas, Friday, Can't come till next Wednesday. I have to deliver parts Tuesday.
Crap
Jim

[gar]

060225-1215 EST USA

What power supply?

Is it the main processor supply? On our machines this is basically a PC supply. There is also a switching supply that runs from the DC bus for the servos and spindle that supplies the low voltage for the servo amplifiers. Then there is the high voltage DC power supply to the motors.

Call me if you want www.beta-a2.com for phone number.

[PBMW]

Gar
When I press the power on button, Nothing happens. No contactor pulling in. Nothing. When it was intermittent, it would pull in the contactor but only briefly. You could hear the contacts close, then power would go away.
When it would turn itself off, it just shut off. No alarm, just shut off.
Now it won't do anything so I can't even check any voltages
Ideas?
Jim

[gar]

060225-1320 EST USA

I do not have a mini so I can not be sure what the HAAS wiring is, but on our VFs the main contactor, I call it CRM, HAAS calls it K1, is directly controlled by the POWER ON and OFF buttons, a holding contact on K1, and a normally closed K7 contact on I/O PCB.

Power to K1 is 24 V AC from T5. Anything in the series loop to K1 coil can cause it to fail to close.

Measure the output of T5 directly. Should be in the range of 20 to 28 V AC.

With your main disconnect open check check for continuity from wire 742 to 743. This will include the coil resistance of K1.

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[Geof]

I think the following is correct but I am doing it from memory.

If you trace the incoming wires you should find there is a circuit that bypasses the main contactor and powers a small transformer which is used to energize the solenoid on the main contactor. Somewhere in the circuit to the transformer there are some fuses. If your main contactor is not pulling down it means it is not getting power and your intermittent problems could have been due to an intermittent open circuit in the supply to the transformer. Have a look at the fuses to make sure they are okay and just simply try pulling out and replacing all the fuses to see if any of them have a poor contact.

[PBMW]

That was the first thing the Haas guy asked me and I told him that the lights by each of those fuse holders were not on , as they would be if the fust were bad. But, I'll go try that in a bit. Couldn't hurt...
Thanks
Jim

[gar]

060225-1502 EST USA

If you have about 24 V AC from the transformer at the transformer, then you do not need to worry about any fuses to that transformer.

Do you have a voltmeter, preferably a VOM so you can also make continuity measurements?

Make continuity measurements by resistance only when your main disconnect is open.
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[chmillman]

Had something similar happen. In my case it started with getting random overload errors on the Z axis, when the mill was idle (VF2). The frequency increased. Then it started happening on the other axes. Eventually it started erroring out in operation. Restarting always fixed it. Service told me that the power supplies (to the main board) go bad bizarrely, that is they are fine for awhile, then suddenly there is a drop in output voltage. When that happens, random errors occur. In any case, once the supply was replaced, no more problem. The service tech knew exactly what it was when I described the symptoms. It does look exactly like a PC power supply, except for the price... :-(( --ch

[gar]

060225-1517 EST USA

chmillman:

The current problem that PBMW is describing can not be the PC power supply.

PBMW has indicated that the main contactor will not close. Look in your manual at the main power input area, and you will see where the currently described problem is located.

PBMW:

Have someone manually hold the main disconnect in. Use an insulated rod. See if you can run the machine. Meaning does the display work, can you do things with the keyboard, and can you jog the machine. If so you need to solve the problem associated with the K1 relay, and this may be your only problem.

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[little bubba]

Originally Posted by chmillman It does look exactly like a PC power supply, except for the price... :-(( --ch

If it looks like a PC power supply it probably mostly is. Our Fadal had it go out, and they wanted like $280. Went around the corner to the PC place picked one up for $40. Cracked it open and went to town. You can keep a newer switching power supply on by jumping, if I remember right, the green and grey wires. Taped off the 3 volt wires and used the rest.

[PBMW]

Just to bring some closure to this little adventure. It wasn't the power supply at all. After an hour and a half of trouble shooting, the Haas guy found that one of the wires to the power "off" button on the front panel had broken at the switch.
Seems that if I would have opened up That panel, I would have seen it right away....But Nooooooo.....
Anyway, Alls well that ends well and I'm back up and running
Thanks to all who gave advice

Jim

[Geof]

Had a problem that was same type on a VF-0. Low air pressure alarm came on and after a lot of time it was discovered a spade connector had come loose on the pressure switch at the top of the spindle.