250 milliamp fuse blows when VF2 is off

Hello,

I recently started having this issue of my 2013 VF2 blowing a small 250 milliamp (1/4 amp) glass fuse that is on one the boards. When this happens the machine will not power up when pressing the green power button. It happens when the machine is off and usually when it stays off for a few days. If I don't power it up for 3-4 days and than go to run it its dead and there is a small orange LED flashing in back that says blown fuse when ON. I replace the fuse and it runs fine without any signs of any issues. The machine has been moved a few months ago to a new shop. Never acted up at all in 5 years. After the move it ran ok for the first 2 months or so than it popped the fuse.

Any guidance where to look for the issue would be appreciated. Haas service came out recently and replaced the internal clock battery and did a full update to newer software. No change in, still pops the fuse at random.

I'm going to make a guess at what is happening. It sounds like the inrush to charge the capacitor in the power supply that the fuse protects is a bit high and when you power off for a few days, the capacitor is completely discharged and thus draws maximum current on power up.

The quick fix for this might be to leave the machine powered up, the idle power draw isn't much and it keeps the electronics at a constant temperature. We leave ours powered up most of the time.

You should check with Haas before doing either of the suggestions below.

An alternative might be to install a 0.25 amp slo-blow fuse.

Another alternative might be to install a 0.315 amp fast acting fuse.

blowing the 250 milliamp fuse I would check the power supplies and the electrolytic capacitors on the control boards

is the mains supply voltage the same in both locations ?
if the mains supply is higher in the new location the switch on surge current may be at the limit of the fuse

did you replace the fuse with the exact same type - quick blow "F" verse slow blow "T" ?

do you have a link to a PDF copy of the manual ?

John

The fuse was a slow blow. I could only get regular fast acting locally so the last 3 fuses were fast acting. Today I can in and it was blown again, but finally got some slow blow fuses that I ordered and will replace so well see if that help.

The current at the new place is a bit higher than at the last place, but the wiring and jumpers were moved to the right terminals for what is coming into this building. The old location had all 3 legs at 120v, and cross voltage was at 210v, but the new place where I am at has 2 at 120v and the 3rd leg is 240v. So cross voltage I think is at 244v.

slow blow fuses are designed not to blow with the initial switch on surge current
the fast blow fuses are not , so you may find every thing work OK when you use the correct fuse

its possible the original fuse failed with old age
when run near to there design limit the effects of temperature cycling as the fuse wire expands and contracts
causes the wire to fatigue

sometimes during the life of a product manufactures increase the fuses rating to stop nuisance fuse failures

John

Quote:

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Originally Posted by john-100

slow blow fuses are designed not to blow with the initial switch on surge current
the fast blow fuses are not , so you may find every thing work OK when you use the correct fuse

its possible the original fuse failed with old age
when run near to there design limit the effects of temperature cycling as the fuse wire expands and contracts
causes the wire to fatigue

sometimes during the life of a product manufactures increase the fuses rating to stop nuisance fuse failures

John

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I got the fast acting fuses as that was the only thing I could get my hands on. So now that I replaced the last fuse that popped this morning with what belongs in there, a slow blow fuse we will see. Hopefully you are right and it was just a fluke or old age of the original fuse. I don't run any kind of production with the machine so leaving it on doesn't make for me as sometimes it doesn't get turned on for 3-4 days at a time.

Thank you for your input so far.

Do you have any clue as to what the fuse is a part of or protecting? Any markings onboard? could also be any number of subsystems that fuse is wired into and the cold startup of that system. Just wondering as that is a pretty low value. Thinking interfaces and logic controls on my side. ???
QUOTE=Dsmed;2233416]Hello,

I recently started having this issue of my 2013 VF2 blowing a small 250 milliamp (1/4 amp) glass fuse that is on one the boards. When this happens the machine will not power up when pressing the green power button. It happens when the machine is off and usually when it stays off for a few days. If I don't power it up for 3-4 days and than go to run it its dead and there is a small orange LED flashing in back that says blown fuse when ON. I replace the fuse and it runs fine without any signs of any issues. The machine has been moved a few months ago to a new shop. Never acted up at all in 5 years. After the move it ran ok for the first 2 months or so than it popped the fuse.

Any guidance where to look for the issue would be appreciated. Haas service came out recently and replaced the internal clock battery and did a full update to newer software. No change in, still pops the fuse at random.[/QUOTE]

Quote:

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Originally Posted by john-100

slow blow fuses are designed not to blow with the initial switch on surge current
the fast blow fuses are not , so you may find every thing work OK when you use the correct fuse

its possible the original fuse failed with old age
when run near to there design limit the effects of temperature cycling as the fuse wire expands and contracts
causes the wire to fatigue

sometimes during the life of a product manufactures increase the fuses rating to stop nuisance fuse failures

John

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I agree with this....

Is it the fuse after the mov? You could try a power logger to see if you are getting too high voltages.

Quote:

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Originally Posted by Dsmed

I got the fast acting fuses as that was the only thing I could get my hands on. So now that I replaced the last fuse that popped this morning with what belongs in there, a slow blow fuse we will see. Hopefully you are right and it was just a fluke or old age of the original fuse. I don't run any kind of production with the machine so leaving it on doesn't make for me as sometimes it doesn't get turned on for 3-4 days at a time.

Thank you for your input so far.

---

check the control circuit and wiring , also check the control voltage

Wanted to give you guys a quick update. So far after installing a slow blow fuse the machine has not blown it. It has had a few days where it would sit off for 3-4 days and its been fine. Perhaps it was just time for the original fuse that was in there for 5+ years to go and as I mentioned the only think I could get in that amperage, size local was the regular fast acting. Once my order came in with the slow acting fuses I replaced it and the machine has been fine.

Now I just need to come up with more stuff to make so it doesn't have to be shut off :)

great news

John