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View Full Version : So close.....am882 driver blowing fuse



Danielroyal25
01-03-2014, 06:38 PM
The control box has been turned on for the first time today and all was going well. The home made psu is outputting 72.5v and after connecting it upto the drives all come on bar one. The fuse had blown 4a fast blow glass type, all wiring and setting are identical in each drive.

Is this a faulty drive or if the stepper has been wired incorrectly would it blow the fuse?

Was looking forward to seeing it finally move after a year but will have to wait a few more hours!

EddyCurrent
01-03-2014, 09:02 PM
The manual is not very helpful regarding fuses, I'm using 5A fuses, the type used in cars but as yet my motors have not been under load conditions.
I don't think the fuse would blow if the motor was incorrectly wired. Your best plan is to make sure the DIP switches on the suspect board are set the same as the other AM882's and check what current you have them set to. Replace the fuse and try it again, it may just be on the verge current wise and switch on conditions made it blow. It might be worth energising each AM882 individually for a start.

Danielroyal25
01-03-2014, 11:30 PM
This is why I'm so confused by it. All the settings are identical on every drive and tried several times with new fuses and they have all blown. I can't see how the other 3 drives are fine but this one isn't. Will see i I have a slightly higher rated fuse and give it a go.

JAZZCNC
01-03-2014, 11:50 PM
This is why I'm so confused by it. All the settings are identical on every drive and tried several times with new fuses and they have all blown. I can't see how the other 3 drives are fine but this one isn't. Will see i I have a slightly higher rated fuse and give it a go.

No don't go higher on the fuse else you risk damage. I'm currently setting up a machine with AM882 and running 1A fuse for safety while testing without blowing fuses so you have a problem some where Dan.

Go over all the wiring again and check connections. You will have a problem somewhere that isn't obvious.
I've built many control boxs now and still I get problems and just today I've spent 5 hours chasing an issue that turned out to be a simple 0v wire in wrong place so it will be something daft like this. Go over every thing with a fine tooth comb.

DONT UP RATE FUSES Whatever you do.

JAZZCNC
02-03-2014, 10:00 AM
Dan I'm at home all day today(Sun) if you want to ring and funnly enough trying to finish off a machine and wrestling with control box's that don't want to play nice. Though hopefully I've beat this one into surrender.!! (Shit I've probably cursed my self now. .:hysterical:)

Clive S
02-03-2014, 10:13 AM
The control box has been turned on for the first time today and all was going well. The home made psu is outputting 72.5v and after connecting it upto the drives all come on bar one. The fuse had blown 4a fast blow glass type, all wiring and setting are identical in each drive.

Is this a faulty drive or if the stepper has been wired incorrectly would it blow the fuse?

Was looking forward to seeing it finally move after a year but will have to wait a few more hours!

Have you tried it with the offending drive's motor not connected to it. Just a thought if you have used cy cable it is possible that you might have a short to the screen of it. Don't disconnect the motor without powering off first. ..Clive

EddyCurrent
02-03-2014, 10:31 AM
This is why I'm so confused by it. All the settings are identical on every drive and tried several times with new fuses and they have all blown. I can't see how the other 3 drives are fine but this one isn't. Will see i I have a slightly higher rated fuse and give it a go.

You didn't say in your first post that you had replaced the fuse several times otherwise I would had said something different.
If a fuse blows once sometimes it's bad luck, but twice indicates a problem and as others have said the last thing is to increase the fuse size. As Clive says try it with the motor disconnected. You could swap the motor from another drive, or swap the board with another board, the trouble there is you might end up with two faulty boards.
If you bought it in the UK you could probably send it back to the suppplier for testing.

Danielroyal25
02-03-2014, 03:17 PM
Will give you a buzz later Dean, thanks.
i will try it without the stepper connected before sending it back as I'm sure it's the driver not the wiring. I'm no eleccy but did a continuity check between the dc in and ground terminals on the drive and it was showing a connection on the faulty drive but not one on the working drive, does this help with a diagnosis?

JAZZCNC
02-03-2014, 03:31 PM
Will give you a buzz later Dean, thanks.
i will try it without the stepper connected before sending it back as I'm sure it's the driver not the wiring. I'm no eleccy but did a continuity check between the dc in and ground terminals on the drive and it was showing a connection on the faulty drive but not one on the working drive, does this help with a diagnosis?

Yes unfortunatly does sound that way but first still go and check your wiring before attaching a new drive because about the only thing these drives DONT protect them selfs against is reverse polarity so if you have got wires wrong way around some where the same will happen. If your unsure put a very low Amp fuse in as a backup for testing, this way fuse will go before any damage to drive.

Danielroyal25
04-03-2014, 11:04 PM
The drivers going back to zapp so will let you know the outcome. Had the x and y working tonight tho :) wrote a bit of text and drew some basic shapes. Can't wait to get the z going and makin some real parts!!

will post some pics and vids on my build log at some point.

Got it a few questions with the setup in Mach:
as soon as the reset button is pressed the spindle starts and gets upto speed, can I change this so the spindle starts once a program is run? I've tried a m5 code but this did nothing.
The text I wrote was mirrored in comparison to the desired is this due to the axis direction not being set up, if so how do you specify the +/- direction of an axis in Mach.
Also the text was around half the size it should have been. In the motor tuning the steps per, is that 200 or, the the microsteps/ballscrew pitch?
running the spindle via Mach, what should the base frequency be?

Danielroyal25
29-03-2014, 07:17 PM
It was a faulty driver. Many thanks to Gary at zapp for replacing it under warranty!

it did it's first cut today!

I have the spindle set up via mach 3, when it runs a program it starts the spindle and starts to cut straight away, is there any way of allowing the spindle to get to speed before it starts cutting. Also should it display the spindle speed on mach?

JAZZCNC
29-03-2014, 08:01 PM
Great news Dan pleased to here it's working.

For spindle you want Ports&pins/Spindle setup/General parameters CW delay.

So Anyway I know I cut lots of parts for it but I've still not seen the finished result and it's long time ago know so it's about time you introduced us to the beast with a few pics. . .:yahoo:

Edit: Mach won't show the actually spindle speed but it will display the commanded speed set in the G-code which if VFD and Mach pulley speeds setup correctly should nearly match the true spindle speed. For the actual spindle speed you'd need an encoder on spindle and feed back to mach.

Danielroyal25
29-03-2014, 08:32 PM
Cheers dean. Will get the pics up soon and some vids on the original build log. Really chuft with the whole thing. It's taken a year near enough and well worth the wait.
I'm sure the questions won't stop here tho....