Thread: How do I blow a driver??
Rather than actually wanting to blow anything up, I was after a bit of guidance on what cock-ups to avoid!
As a novice I've just taken delivery of a system4 kit from Roy of DIYCNC.
From reading round these forums I've picked up not to mess about with motor connections with the power on.
Are there any other things to avoid that might not be obvious to the uninitiated?
If a motor stalls does that damage anything?
How necessary is it to use screened cable to the motors?
Roy's manual suggests starting off with the boards set to min current to start with.
Any input welcome, no suggestions are too basic!
I have the system 3 from Roy and I know from experience that if you accidentally wire the motor up wrong it will blow the driver. In that case, and possibly with system 4 as well, the main chip was plugged into a holder not directly soldered so it cost about £10 to repair.
I used screened cable but I think that's not required. Someone will correct me I'm sure!
Like Rcn says make sure motor phases are correct. Sheilded cable or unshielded won't damage the drives in any way but with unshielded you run the risk of introducing electrical noise into the system and control signals which can and will cause eratic hair pulling probelms and send you round the bend so just not worth skimping on.!!
Stalling motors won't do any damage what so ever to drives or motors.
NEVER disconnect the motors from drives with power ON,(this goes for any driver not just Roy's) 99.999% time it will blow drives.
Don't give them more than the drives rated Voltage or even the actual rated voltage as back fed current from motors when de-accelerating could blow them, best to leave a small safety margin IE 30V drives use 24V PSU. This why it's best to buy drives with spare capacity.
Setting the amps too high will just make the motors run rough and get hot, It may or may not on Roy's drive do damage(Doubt it.!) having them set too high but on most singel drive setups it doesn't hurt them just makes the motors sound and run awfull.!
Double check and triple check all soldered or crimped connections, esp motor connectors for the above said reasons and if you have any strange happenings while in use, like missed steps or false limit or E-stop triggers this should be the one of the first places to check along with ground connections.
NEVER run signal cables, either motor or limits, E-stop etc along side power cables IE Spindle power this is a sure fire way to introduce electrical noise and premature baldness.!!
Also don't cable tie signal wires together, just let them run side by side with small clearence.
ALWAY ALWAYS use a Star grounding system taking each ground connection back to one main ground point.You can run multiple grounds to a main grounding block but only one (fatter)cable should come from this to the main grounding point.
Only ground one end of sheilded cable and do this again to the main control box Star ground. The only exeption to this is VFD spindle cable and this can or recommended to ground both ends.
Hope this helps and don't be affraid to ask if your not sure.!! . . . . Avoid the magic smoke at ALL COST's. .
Last edited by JAZZCNC; 20-04-2012 at 02:24 PM.
The Following User Says Thank You to JAZZCNC For This Useful Post:
Thanks for the advice!
Still smoke-free and just had it spinning a motor on the bench (well, dining table)
Just have to bung the motors on the machine now...............
One step forward, one stepper back........
Have now wired up all 3 motors with screened cable and am getting seriously weird results!
The x axis seems to be the centre of the problem - this motor performs some random stepping with no signal from Mach3??
The other 2 seem to be OK most of the time BUT I have had all 3 spinning when I click the RESET on the Mach3 screen to STOP them!
To track down the x axis thing I have swopped motors, driver boards, and motor connectors - none of which changed it so I think it must be a motherboard thing?
There aren't any settings in Mach3 I could have wrong enough to cause any of this are there?
Check your bios to see how the par port is set up to either epp or ecp. Try both to see if it makes any difference.If the nagging gets really bad......Get a bigger shed:naughty:
( Nothing dodgy Lads just offering help via phone has I can't look at screen long with my knackerd eye. . )
The Stevie Wonder School of CNC fault Finding.John S -
Soooooooooooo much work to do, loads of G-code to create but can't look at the bloody screen for more than 2mins without eye's piss buckets of water.!
Suppose should do what the doc orders and go to Bed but can't bastard sleep for thinking about all the shit I've got to do. .Arghhhhhhh.
Thanks to 2e0poz and especially Dean, who spent an hour on the phone with me last night - a case of the nearly blind leading the blind!
BIOS was set to ECP, now EPP, no change.
Wasn't certain had loaded demo version of Mach3 from the Artsoft site so did that - no change.
Voltages between GND and DIR pins on xyz driver boards all were less than 0.2 or more than 4.8 when active.
Heres something else - I unconfigured the x axis on the ports and pins page (enable off, pins to 0, port to 0) and the x motor STILL grumbles and turns in the same way with no Mach activity!
One other thing, the desktop is a 2.2GHz Compaq Presario. The drivertest program shows a message 'pulsing too fast' but the pulses per sec show as about 15000 to 17000 where I believe 25000 is required, BUT in Mach3 diagnostics page pulses is always within 10 of 25000. These seem to be contradicting messages?
Will have to do some work this morning but unless anyone has inspiration will post motherboard/BOB/cable back to Roy this afternoon (as he has suggested).
So it looks like I'll be back working on motor mounts tonight!
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