Help, machine is down. I think it is a power supply, maybe?? Help!

DavidScott · Aug 29, 2020

It shut off, no alarms, while raising the head to do a tool change. Control was off and would not come back on. I shut it off, opened up the back cabinet, and powered it back on. The control would still not come on and I noticed the 24 volt alarm light was on on the power supply. This is on a 2001 Kitamura with a Yasnac J300 control. I have a 1996 Enshu with a J50 control with what I think is the same power supply in case that helps. I have 3 photos showing the two power supplies and the alarm on the one. I don't know much about electronics but generally know enough to not cause more trouble. What should I do? Unplug all wires from the alarmed out supply except for the control wires and see if it clears the alarm. If so then figure out which connector is the problem? Thanks for any help.

BROTHERFRANK · Aug 29, 2020

Not familiar with those but curious if you can power up with Estop activated? Some machines this will disconnect the servos. If there is a short in a motor this may allow it to power up.

Ziggy2 · Aug 29, 2020

You probably have a short. Looks like on the 5vdc side. This is likely why the 24vdc is also unhappy. The power supply is likely okay. I would not be swapping it out.

If you have the schematics for your machine, I would start by tracing the 5vdc bus lines.

Unplugging the cables likely wont help much since it looks like you only have a couple of wires feeding 24vdc and 5vdc. Problem will likely be either a wiring harness worn thin or a metal chip in a wire, shorted to ground. Could also be a bad 5vdc capacitor but they usually smoke when they fail. Whatever the problem is, it will be generating heat.

Hardplates · Aug 30, 2020

I don't know how far Vancbiker is from you but you might consider getting in touch with him and seeing if he would be interested in taking on such a job.

SteveEx30 · Aug 30, 2020

Verify all the voltages on the power supply and see what one is missing.. If you are not getting correct voltages then proceed to isolate the power supply from the machine. Check voltages again. If they are good now, you prob have a short somewhere in the machine . If the voltages are still no good then it's the power supply.

I just went thru this on one of my machines and traced my +24 to a shorted limit switch wire.

DavidScott · Aug 30, 2020

Vancbiker is about an hour away or so but I want to see if I can figure this out before asking/begging for help. He did come out to look at a spindle problem I have back in February which I am eternally grateful for. I had a similar issue on a Takisawa lathe with a Fanuc 3 control 18 years ago. I finally traced it down to a bare wire someone left flopping around after replacing a gage, and while I did it I tried like hell to burn what I learned into memory. So here goes...

I have traced the problem down to an I/O board. With the power to that board unplugged the control will power up and the voltages are spot on. With it plugged in and the E-Stop active the PS will alarm out as soon as I try powering up the control. What I think I should do next is to unplug everything to that board, except power, and see if the alarm clears. If it does then start plugging things back into it, while the power is off, until I find what plug is causing the problem, then start tracing those wires to see where they lead. Is this what I should do?

I have all the documentation for this machine from Kitamura as well as all the manuals from Yasnac for it.

Here s a photo of the I/O board. I looked it over and don't see anything wrong.

DavidScott · Aug 30, 2020

Bump.

Can it cause problems if I disconnect all cables, but power, to the main I/O board in an attempt to find the short?

Hardplates · Aug 30, 2020

DavidScott said:
Bump.

Can it cause problems if I disconnect all cables, but power, to the main I/O board in an attempt to find the short?

While I would think that would be ok I'm not familiar with it and can't say for sure. If it were me I would start at the output of the power supply and figure out if the 5 volt or 24 volt is being pulled down by disconnecting each dc bus one as a time. If you have a CT meter that will capture DC inrush you may be able to ID which DC bus is getting pulled down without disconnecting them.

DavidScott · Aug 30, 2020

Hardplates said:
While I would think that would be ok I'm not familiar with it and can't say for sure. If it were me I would start at the output of the power supply and figure out if the 5 volt or 24 volt is being pulled down by disconnecting each dc bus one as a time. If you have a CT meter that will capture DC inrush you may be able to ID which DC bus is getting pulled down without disconnecting them.

All I have is a cheap multimeter and not much knowledge. I am thinking my problem lies in the tool pot swivel mechanism. The machine alarmed out right when it reached vertical position in preparation for the tool change. With it down it is damn hard to access the wiring though. There are several wires on top and it's packed with big curly aluminum chips from my facemill.

In the spirit of not screwing something up, I will wait to talk to Kitamura tomorrow before unplugging and powering up.

Hardplates · Aug 30, 2020

DavidScott said:
All I have is a cheap multimeter and not much knowledge. I am thinking my problem lies in the tool pot swivel mechanism. The machine alarmed out right when it reached vertical position in preparation for the tool change. With it down it is damn hard to access the wiring though. There are several wires on top and it's packed with big curly aluminum chips from my facemill.

In the spirit of not screwing something up, I will wait to talk to Kitamura tomorrow before unplugging and powering up.

I take it nothing looks toasty on the I/O board?

DavidScott · Aug 30, 2020

Nope, all looks good. Hey, the pot rotator swings freely with the air and power off! Just don't let the pot fall out with the air off!!

DavidScott · Aug 30, 2020

Well, I pulled the cover off, pulled the coolant and chip covered wires out, wiggled them around and cleaned them up, and it powered up just fine. Now how do I find the problem!

Hardplates · Aug 30, 2020

DavidScott said:
Well, I pulled the cover off, pulled the coolant and chip covered wires out, wiggled them around and cleaned them up, and it powered up just fine. Now how do I find the problem!

If there is nothing obvious, personally I would clean it out and run it. If the problem comes back you know where the problem is and with the schematics which wires to check for shorts. Now that it isn't shorted it will be 10 times more difficult to find unless you can reproduce the shorted condition.

DavidScott · Aug 30, 2020

Yeah, it's only control wiring so no energy, right? I am hoping one of the chips bridged the gap and caused the problem. There were a few that worked their way into the caps insulating the wire connections. Truly amazing where chips can get to. This is 20 inches directly above the cutting tool with a good cover protecting them.

Ox · Aug 31, 2020

You are up and running now right?

Anyway - your initial post is correct, and I just did this a month ago...

Unhook all warrs from the load side of the power supply, and then add them back on 'till it drops out, then chase that down as it may divide out many times yet.

You will likely find it in an hour.

But sounds like you are good to go for now...

------------------

Think Snow Eh!
Ox

DavidScott · Sep 1, 2020

Ox said:
But sounds like you are good to go for now...

------------------

Think Snow Eh!
Ox

Two steps forward one step back. Absolute encoders lost position so I had to reset. Z axis homed fine but the limit switch plunger on the Y axis stuck, obviously been a while since it was used. I got one loose but the other is still stuck. Just one of those days.

Garwood · Sep 3, 2020

I've had two VMC's that had intermittent issues when near or at home position. It was worn wires in the cableway going to the headstock on both of them.

I know nothing about Yasnac. I think Kevin's out of town. Haven't heard from him in a few days.

DavidScott · Sep 3, 2020

A bad energy week or something. Turns out the limit switch plungers were full of coolant and the one I needed had been seized for a long time, it is only active when you home the axis after resetting the absolute encoders. The vent for the plungers is on top of the housing allowing the coolant in. After fixing it up and getting it working right it then homed the Y axis fine. X axis though alarmed out. Off with the cover, a few drops of way oil the plungers, cycle them till they feel right and try it again. Alarmed again but differently. The Jengish made me think the switch was double-clicking so I bumped the rapid up to 25% and it made it to the other side of the dog before alarming out where the plunger drops off the dog at 1% rapid. I try a few more times and finally the last axis homes out, yipee. It's the end of the day so I shut it down since all should be good. Power it up the next morning and get an alarm I haven't seen in a few years, I think it's the Ethernet card didn't boot up. Power off, back on, and voila, we are up and running. 2 days in without any more problems so I am hoping that is behind me.

Ox · Sep 3, 2020

... 'till next time...

If you have to take the L/S off, maybe you should drill a weep hole to let the coolant out.

----------------

Think Snow Eh!
Ox

Help, machine is down. I think it is a power supply, maybe?? Help!

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