A couple of G540 questions

[cyclestart]

Apologies in advance for not searching through the 1700+ posts 'cheap drives' thread.

My current 3 axis system is now a 2 axis system A bit of uneducated postmortem suggests the failure was my fault. A chip probably bridged a couple of the motor leads. The design of this drive is 'all-in-one' so it will be put to use in a lathe project with the remaining 2 axis.

If an individual axis fails on the G540 is the repair usually as simple as installing a new G250? If so, is this easily done by an unskilled customer?

Is a short in the motor cabling certain death for any stepper drive? Is the G540 less prone to this type of failure?

Do you attempt any repairs on returned units or is the policy to simply replace? Sorry to be talking failure pre-purchase but these are things I didn't consider before buying my current drive.

[ger21]

I believe its as simple as plugging in a G250. But aren't there 4 in there already? If you only need 3, you should already have your spare. Just plug the motor into the other plug.

Yes, a shorted wire usually means instant death, except for the G203V, which can take almost anything you can throw at it.

[Mariss Freimanis]

The G540 motor outputs are protected against short-circuits (winding to winding, winding to ground, etc.), reversed power supply polarity, over-voltage and under-voltage. The protection is pretty much the same as what's in a G203V except for over-temperature protection.

The G540 contains four individual G250 drives. Each are held in place with a pair of 2-56 socket head screws. Replacing the drives requires only an Allen wrench. The cover unsnaps and the motherboard unplugs to reveal the four drives. There are no wires inside at all. Simply unscrew the bad drive, replace it, plug in the motherboard and snap the cover back on.

Reversed supply polarity or over-voltage (>68VDC) will blow an internal ultra-fast fuse. The fuse is socketed on the motherboard. Unsnap the cover, unplug the motherboard and replace the fuse. Plug the motherboard back in, snap on the cover and it's good to go.

We have yet to see a blown drive but then there aren't that many G540s out there yet, less than 1,000 have shipped to date. I have dealt with a few support calls where the G540 wouldn't come out of fault (red LED) where the cause was traced to a shorted or miswired motor. Clearing that resulted in the G540 running (green LED) with no damage to the drives.

Mariss

[cyclestart]

Sounds great. SOLD! . Now give me a week to sell my wife on the plan.

[Mariss Freimanis]

Tell her it comes with a cute little stuffed toy gecko.:-)

Mariss

[TOTALLYRC]

Originally Posted by Mariss Freimanis Tell her it comes with a cute little stuffed toy gecko.:-) Mariss

Hey cycle start. Try this on your wife. Tell her that you could be at the bar or doing drugs or chasing other woman. In my case I am in the backyard 50' from the house where she can always find me. Once you make a few things for her from the new machine tool it gets easier.

My wife doesn't care for my "hobby" either but she loved the gecko. It has a place of honour on her dresser.
Thanks Mariss.
Mike.

P.S. I will install those G251's sometime but the one time special was just to good to pass up.

[Fixittt]

I popped the case on my g540 to move some of the driver boards around, and I was totally impressed with the design of the unit. It will take you a total of 6 minutes to replace a single axis in the g540. Ok 6 minutes to replace any and all of them if the need was there. I say 6 minutes because I tried not to scratch the black anodizing on the unit itself.
It is this simple. Unplug all the stepper connections, the LPT cable and pop the back off. The motherboard pulls out of all the drives. Remove 2 small allen screws replace driver board. Press motherboard back into drivers, pop casing back on, reconnect cables.

[resistor]

Reversed supply polarity or over-voltage (>68VDC) will blow an internal ultra-fast fuse. The fuse is socketed on the motherboard. Unsnap the cover, unplug the motherboard and replace the fuse. Plug the motherboard back in, snap on the cover and it's good to go.

Well that gives me cause to wonder...
To add similar protection to an otherwise bare G251 drive,
is that as simple as adding an "ultra-fast fuse"
inline on the star DC supply to each drive?
Or is the fuse only part of a crowbar circuit
incorporated in the G540 motherboard?
res out

[Mariss Freimanis]

Much more than just a fuse is involved. It is only small part of the protection circuit and it only protects against polarity reversal, not short-circuits.

Mariss

[resistor]

Marris,
Thank you for the prompt answer.
Another question if i may...
Would it be beneficial to place a ultra-fast fuse inline on the dc input to the G251?
If so, what rating would be correct?
What about:
http://search.digikey.com/scripts/Dk...?name=F2439-ND
or:
http://search.digikey.com/scripts/Dk...?name=F2333-ND
Is 4A too close?
(with suitable heat shrink tubing,
inline on power supply terminal strip)
Currently i have one 10A 1/4" glass fuse in the positive
supply line before terminal strip for individual drives.
Thank you,
res

[Mariss Freimanis]

Try a Digikey F2314-ND which is an ultra-fast 2A fuse. Use one per drive.

Mariss

[resistor]

Thank you!
Added to my order.
Oh, and thank you for the G251s.
Now if we can just get the gantry finished.
res out