[blakemachine]

Ok, in some older post I have shared problems about my miyano lathe with fanuc 6t Control. What happens is every morning I start the machine, and after a minute or so the machine will shut down with the red LED on the power imput unit lit. I then took Al's advice as well as others and started taking one lead off at a time on the power supply that is right next to the imput unit. I took all of the 5v ones off one at a time as well as the 24v ones off one at a time. The problem still occurs, even at each time one is off. The thing is, is that this problem usually goes away after about an hour of turning the control off and on say 20 times or so, and then will run the rest of the day with no problems. I have take all of the limit switches out, cleaned them, ohmed them and all seems well. I am not sure where to look next for this shut down problem? I changed the two smaller relays on the power imput unit, thinking one of the contacts could of been stuck. It did not help.

[fordav11]

if you power the machine on and leave it on for an hour but not run it does the shutdown still happen? if no then you probably have a dry solder joint somewhere in a power supply or power related circuit board.

[hitachibos]

try disconnecting your coolant pumps before you turn it on next time. so many times i have seen an internal short from wet windings cause a similar issue.

[memoryman]

Try heating/cooling selected areas of the motherboard. The powersupply can certainly cause this and is my first choice.

[Harmeet]

just switch on the machine without running it, keep emergency pressed..
If machine still goes off then there might be some problem with the power supply or mother board..
if machine doesn't goes off then after an hour make machine ready after releasing emergency switch but don't run the machine, if machine goes off there can be problem with I/o card or the inputs and ouputs which are working without running machine...
Now if machine still doesn't goes off then there can be shorting in limit switches, operator panel, tower lamp,foot switch etc,
check one by one....

[blakemachine]

It does the same thing with the E stop pressed or not. Which I think would be consistent with it doing it also every time with the leads pulled off of the 24 and 5v output of the PS.

[hitachibos]

did you try the coolant pumps ?

[blakemachine]

Yes I did, and it did not help.

[Al_The_Man]

There is a test system that is in the Fanuc training manual that shows how to stop the red LED fault on the input unit from shutting the power supply down, but it has to be done with caution as obviously something caused the shut down and jumpering it out does not remove the fault, so take care if this method is used.
The problem is there is many types of Input units, but the basic premise is the same.
The one I was shown was to jumper out the P1 & P2 pins to hold in RY1 on.
One problem in your case is that if the fault happens momentarily and causes the shut down, the fault has come and gone when you manage to jumper it out.
Al.

[blakemachine]

This is the imput unit

[blakemachine]

So here is the P1 and P2 and jumpering these will keep RY1 Engergized?

[alexfanuc]

The input unit is there to protect the power supply from a short.
You probably have a bad power supply unit.
(capacitors in the power supply, perhaps?)
Regards
Alex

[blakemachine]

Ok, I jumpered P1 and P2 and it keeps RY1 Energized through the failure detection. But now it just freezes, or locks up the control when the Red LED gets lit. I am leaning PS by what people are saying.

[Al_The_Man]

In most input units, yes, but I would caution against leaving a permanent jumper as there will be no protection for the P.S. if in fact there is a problem on an output causing this, this is done only in a cautionary sense.
Al.

[blakemachine]

After the machine has not done it in about 20 minutes it will run for days without a shutdown, as LONG as I do not turn the machine off. Even with the E stop pressed overnight without running parts, when I come back in the next morning, I can simply undo the estop and hit cycle start and it will run all day without a shutdown. I would think it is thermal related to something in the power supply. Just now sure what component of the PS would be thermal sensitive to where when it is cold it has problems but when it is warmed up it works fine. Guess I could mount a heat gun in the cabinet.............................

[blakemachine]

I did take off the jumpers on the imput unit. THanks Al.

[blakemachine]

It was the power supply. There were no shorts. We changed the power supply with another one and it has not shut down at all.

I am curious what would of failed in the original power supply? Anyone know of any known problems other than caps disinigrating over time?

[memoryman]

Could be any component or a solder joint. Not worth repairing imho.

[tmbruno28]

tell me in PM if your power supply is a B001 or B002 model and i will tell you 2 or 3 ways of repairs....