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Losing steps/position, again
First had this problem in January on a Denford Microrouter driven by Mach3.. http://www.mycncuk.com/threads/13372...osing-position
Replacing the BOB fixed the problem last time (or so I thought) but now it is back. The router has been in use about 8 hours a day 6 days a week since replacing the BOB. A few weeks ago the X,Y&Z just stopped mid cut with the spindle still running (spindle is controlled via a plugin) pressed the cycle start and the program ran fine. All appeared to be well until last week when it started losing steps again on all axis but more noticable on X.
The fault is now present all the time except every now and then after turning everything on I can sometime jog smoothly for a few minutes before it shows. All connections to the BOB checked and the power supply is a constant 24volts. Nothing has been changed or moved and there is nothing else running in the workshop. The only other thing I can add is that since the fault has returned
After searching the forum for a day the only pertinent commet I can find is one left by JAZZCNC
Bob's are sneaky bastards they trick you into thinking they are fine so you go round in circles chasing other things but then you end up back at the BOb and soon has you change them out every thing works fine.!
So would I be better off investing in a better BOB, and if so which one? This is what is in there now
https://lozharroplures.co.uk/my_images/1.jpg
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Re: Losing steps/position, again
That still holds true but there are things you need to check and procedures to go through before you condemn the BOB.
If it's just missed steps while in use and not when things turn on like Vacuum or Spindle etc, which could be electrical noise, the first thing to check is the mechanicals.
It doesn't take much binding to stall a small stepper motor when rapidly moving from position to position so if you have a sticky axis this could be the cause. Try to take note which axis loses steps and whereabouts in the Job it loses steps, ie: Rapid moves, etc.
If the mechanicals is good then it could be that you just have it over tuned and it's close to the edge where torque drops away, but only on certain moves like rapid moves.
An easy test is to just lower the velocity in motor tuning slightly and see if it still loses steps.
What is the velocity and acceleration in Motor tuning for each Axis.?
I would check out the mechanicals first before doing anything else.
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Re: Losing steps/position, again
Cheers,
No vac on and tested today without power to VFD so I think I can rule that out.
As it is losing steps in all directions (though X is most noticable) I am tempted to also rule out mechanical binding?
I will look at the velocity and acceleration tomorrow and post settings/results.
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Re: Losing steps/position, again
Quote:
Originally Posted by
ngwagwa
As it is losing steps in all directions (though X is most noticable) I am tempted to also rule out mechanical binding?
It would be a mistake not to check it out.
What machine is it again.?
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Re: Losing steps/position, again
Denford Microrouter.
Last time it was faulty I did clean all the nuts but it was only when I fitted a new BOB that it stopped knocking and losing steps.
I have just been over to the workshop and regarding the velocity and acceleration settings X and Y were set at 3000 and 150. When first turned on (lo and behold) the machine jogged several times along X with no knocking. Set them to V=1000 and A=50 was knocking when jogged, Also tried 500 and 20 still knocking.
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Re: Losing steps/position, again
I had a PC that would knock / lose steps on every 360 degree rotation of the screw on every axis.
I re-installed windows and the issue was gone.
It was an error with NT driver in windows that came up every so often.
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Re: Losing steps/position, again
Quote:
Originally Posted by
dazp1976
I had a PC that would knock / lose steps on every 360 degree rotation of the screw on every axis.
I re-installed windows and the issue was gone.
It was an error with NT driver in windows that came up every so often.
When I first had this fault I did try a completely different PC and it didn't solve the issue. On the other hand if the problem was as consistant as yours it may be easier to solve.
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Re: Losing steps/position, again
Maybe worth taking a video because missed steps don't really knock.? A knocking would certainly make me think mechanical.
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Re: Losing steps/position, again
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Re: Losing steps/position, again
Quote:
Originally Posted by
ngwagwa
That's not missed steps. It could be something electrical or computer related with parallel port causing problems with the pulses, possibly? However, the first place I'd start is with Motor and pulley couplings, belts etc and checking out the mechanicals.
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Re: Losing steps/position, again
Quote:
Originally Posted by
ngwagwa
The fault is now present all the time except every now and then after turning everything on I can sometime jog smoothly for a few minutes before it shows.
Is anything getting hotter than it used to? Have you dusted the PC processor heatsink and fan lately?
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Re: Losing steps/position, again
[QUOTE=JAZZCNC;115603]It would be a mistake not to check it out.
BINGO and thanks to JAZZCNC. Disconnected the drives nuts and jogged for about 10 minutes with no knocking noises, gave them a liberal spray of silicone lubricant, reassembled and all seems sweet.
So, is it possible to replace the stepper motor with one with a bit more gut? I can't see any markings on the current ones.
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Re: Losing steps/position, again
[QUOTE=ngwagwa;115630]
Quote:
Originally Posted by
JAZZCNC
It would be a mistake not to check it out.
BINGO and thanks to JAZZCNC. Disconnected the drives nuts and jogged for about 10 minutes with no knocking noises, gave them a liberal spray of silicone lubricant, reassembled and all seems sweet.
So, is it possible to replace the stepper motor with one with a bit more gut? I can't see any markings on the current ones.
Great glad your sorted.
Regards changing the steppers then often with these machnes if using original boards then it's not the steppers that are weak it's the fact they are run with low voltage drives, usualy between 30-40Vdc depending on model. Changing the steppers alone won't make any difference because the drives and voltage are the weak link.
Are you using the original drives etc that came with the machine.?
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Re: Losing steps/position, again
Hi, The control box is a right jungle but as far as I can see the original drivers are used for X,Y&Z and there is an additional HY-DIV268N-5A for the 4th AXIS. As I am not using the 4th axis could I try using that driver?
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Re: Losing steps/position, again
Quote:
Originally Posted by
ngwagwa
Hi, The control box is a right jungle but as far as I can see the original drivers are used for X,Y&Z and there is an additional HY-DIV268N-5A for the 4th AXIS. As I am not using the 4th axis could I try using that driver?
Won't make much difference if you haven't got the volts to go with it. Volts are what give steppers there speed.
To be honest without knowing more about what's inside I'm relutant to advise any more and suggest until you know exactly what you have and the voltages you have that you don't go messing about because it's very easy to kill these boards.
Based on expereince of these machines I think you'll find the only way to get them to go faster and be reliable is a full retro-fit with new drives, psu and motion controller the motors you can usually keep. When this is done it transforms the machine to another level, but it costs money.
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Re: Losing steps/position, again
Am I correct that a retro-fit would mean a new motion cotroller, PSU and 3 new drivers and if this is the case could I (for the time being) just use a new driver on the X Axis and use two HY-DIV268N-5A drivers for Y and Z?
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Re: Losing steps/position, again
Quote:
Originally Posted by
ngwagwa
Am I correct that a retro-fit would mean a new motion cotroller, PSU and 3 new drivers and if this is the case could I (for the time being) just use a new driver on the X Axis and use two HY-DIV268N-5A drivers for Y and Z?
Yes for the best effect a full refit is required. However like I said before it's the volts that give you the speed and with those drives, you have a maximum of 48v. However, they are rubbish TB based drives and if you run them anywhere near 48v they will die quickly so you are going to be limited to around 40vdc to be safe.
You need to test the voltage the drives are running at now to get an idea of what will work best. If you do buy new drives then go for something better than those you have. Digital drives are cheap now and can be found for around £40. They will outperform those drives by a large margin and be much smoother and more reliable.
Also using an Ethernet-based motion controller will make a massive difference to how the machine performs compared to the parallel port. When combined with Digital drives running with a voltage around 56Vdc the performance compared to the standard machine will blow your mind.
I converted what I think is the exact same machine(using original steppers) and it would easily reach 15Mtr/min rapid speeds but was derated to 10mmtr/min for use and will cut at those feeds if required. It's been running flawlessly for nearly 3yrs and is used every day to make molds etc.
You really do get what you pay for, so if you want the best save up and dump the rubbish your using now.
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Re: Losing steps/position, again
Well, having just been browsing I was looking at Ethernet (as it is one thing I understand)
My spindle is controlled via a serial port and a plug-in so that is one thing I don't need to worry about.
Saving up is not an option as having the router misbehave is costing me money, so having just spoken to my pension provider it is time to start planning.
By my reckoning I need:
1) an Ethernet based motion controller
2) a connection block and cable to the controller
3) PSU
4) 3 drivers
Mount all these on a board, (now it gets tricky) connect the outputs from the current drivers and the limit switches/probe switch to '#2. Rip out everything from the control box and install the new setup.
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Re: Losing steps/position, again
I have just had my head in the control box and I can't see anything that may be the drivers for X,Y and Z. It looks like the guy that converted it to mach3 thought the easiest way was to hang an old plastic kitchen chopping board to mount the new BOB on right in front of the original control board.I will just have to wing it and make sure I find the stepper motor leads when I remove the existing circuitry.
After spending last night looking at possible options I am drawn to an AXBB-E Ethernet motion controller and breakout board combined controller as includes a BOB plus it is in stock at https://www.stoneycnc.com/axbb-e-eth...r/a4753?c=3479.
Can you suggest suitable drivers and PSU?
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Re: Losing steps/position, again
If I did it again I would get drivers that are rated upto 80Vac/110vdc and use a 70Vac toroidal transformer.
Something like a 2*35vac secondary outputs wired in series for 70vac.
Doesn't matter wether you have Nema 17/ 23/ 34size motors etc, the drivers regulate output voltage to the motors themselves.
For the bb-e it needs 5v and 24v. Could use either voltage stepdowns from the toroidal or seperate switched psu's. Depending on how many relays you have will determine what amp rating they will ideally need to be.
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Re: Losing steps/position, again
Would this be suitable for the transformer? https://cpc.farnell.com/multicomp/mc...%20transformer
Is that all I would need?
You will have to forgive my ignorance as I have an nane fear of magic blue smoke.
Can you suggest any suitable drivers preferably available in the UK? I did find these https://www.cnc4you.co.uk/Microstepp...tepping-CW8060
I will be using the existing 5 and 24V transformers.to power the bb-e
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Re: Losing steps/position, again
Quote:
Originally Posted by
dazp1976
If I did it again I would get drivers that are rated upto 80Vac/110vdc and use a 70Vac toroidal transformer.
Something like a 2*35vac secondary outputs wired in series for 70vac.
Doesn't matter wether you have Nema 17/ 23/ 34size motors etc, the drivers regulate output voltage to the motors themselves.
That's WRONG information your giving out, the drives don't regulate the voltage they regulate the current. 70Vac which is 98Vdc would destroy those little motors in no time at all. It would also make them run like a bag of shite.
You cannot stick any voltage you like into a stepper, there is a limit where it starts to have very negative affects. Namely iron losses and motor heating which kills them.
Those Large voltage Ac drives are only really any good for larger steppers Like Nema 34 or very high inductance NEMA 23's. Your typical 3-4Nm 4.2a Nema 23 with 3-4mh inductance doesn't like to be run much more than 80vdc and at that, you are pushing them past there design threshold so are shortening there life.
For the NEMA 23 motors, which this machine will have fitted he'll only need drives with a max rating of 70Vdc and would run them around 55-60Vdc. Or 50Vac drives running at 40-45Vac.
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Re: Losing steps/position, again
Quote:
Originally Posted by
JAZZCNC
That's WRONG information .......
Thanks - obviously reducing the power I supply will also reduce the initial outlay (as well as havingto replace everything including burnt oout motors).
Could you be so kind as to point me in the right direction for what you would suggest and is there ay advantage with a toroidal transformer (a plug and play box suits me if possible).
Although I have asked elsewhere on this forum have you any reasons why I shouldn't use the AXBB-E motion controller?
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Re: Losing steps/position, again
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Re: Losing steps/position, again
Quote:
Originally Posted by
ngwagwa
My advise is STOP don't buy a single thing until you have settled on exactly what your fitting or need. Also what you have in the machine already that you can re-use.
Those drives are a little over kill but that won't hurt, however, the advice you have been given regards the drives controlling Voltage is Wrong so ignore it.
Those little motors won't like being run much above 60Vdc so the extra capacity the drives allow you cannot really use, but it's always better to have drives that are under performing than being pushed to there limits.
Regards the transformer then the voltage is about right at 35V giving approx 50Vdc when rectified but the Va rating is a little on the low side, 500Va would be better. 300Va would work for those motors but doesn't leave any room for expansion or larger motors in the future 500Va would.
When you say you have 5 and 24v in the machine are you sure it's DC because if it's the original PSU then they tend to be AC transformer and it gets rectified on the boards for the drives to around 32V.
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Re: Losing steps/position, again
Hi,
There is a 5v and a 24v transformer which I think are DC (I did take pictures but have left my phone in the workshop), I assume they were fitted when the machine was converted to Mach3 they are certainly not part of the original controller.
My spindle is controlled by a plugin and serial port which I am happy to leave as is.
I would prefer to purchase a PSU as opposed to building one unless there is an advantage going the toroidal route. Regarding your comment on the 300Va being sufficient but no room for expansion could I fit bigger motors if I needed to or would I need to if the new set up get the most out f the current ones?
As to using what I can I was assuming that with a new motion controller, PSU and drives apart from the 5 & 24V transformers everything else would be redundant bar the mains on/off switch.
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Re: Losing steps/position, again
Quote:
Originally Posted by
ngwagwa
Thanks - obviously reducing the power I supply will also reduce the initial outlay (as well as havingto replace everything including burnt oout motors).
Think I've just answered this one in last post but sorry you need larger not smaller for the reason stated below.
Quote:
Originally Posted by
ngwagwa
Could you be so kind as to point me in the right direction for what you would suggest and is there ay advantage with a toroidal transformer (a plug and play box suits me if possible).
Ok well the advantage with toroidal transformer, when used with capacitors and bridge rectifiers that make up a DC PSU, (yes you need these as well) is that it means you can get away with lower power rating than you would need with a switch-mode supply. You can also build to the exact power requirements you need.
It gets complicated but in a nutshell, let us say you have 4 motors all pulling 4a which means you'd need a 16a for a SWM supply to work reliably and keep up with drives/motors demands when working hard. In practice, the actual rating needed will be higher for reasons I won't get into now. But all this means a Large SWM PSU this size gets expensive quickly.
Whereas a Toroidal/capacitor-based PSU allows you to get away with PSU size only 60% of the motors total draw. It does this by drawing from its bank of capacitors and how the drives work. It also ensures a smoother flow of power because you always have a reserve in the capacitors.
So again, in a Nutshell, yes it's best for these reasons and the fact can size to exact needs and it's often much Cheaper when higher power is needed which is why it's used so much on routers and DIY builds.
Regards the AXBB-E Controller I have never used one personally so I'm not recommending you use it but I do know several people who have used them and are very happy with them. I've fitted several of its Big brother the Uc300ETH and they are also very good so I cannot see these being a bad card. The UCCNC software is also very good so I wouldn't hesitate if it was me.
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Re: Losing steps/position, again
Quote:
Originally Posted by
ngwagwa
There is a 5v and a 24v transformer which I think are DC (I did take pictures but have left my phone in the workshop), I assume they were fitted when the machine was converted to Mach3 they are certainly not part of the original controller..
Ok if that is the case then your sorted. It would be a good idea to post picturs of inside the control box.
Quote:
Originally Posted by
ngwagwa
My spindle is controlled by a plugin and serial port which I am happy to leave as is.
If you go with the AXBB and UcCNC software then you won't be able to use it and I would use the UcCNC software over Mach3 as it's getting long in the tooth.
Quote:
Originally Posted by
ngwagwa
I would prefer to purchase a PSU as opposed to building one unless there is an advantage going the toroidal route.
Ok well in that case look for a Unregulated Linear Supply. Gary at Zapp automation used to sell 48Vdc Leadshine Unreg PSU's give him a lookup.
Quote:
Originally Posted by
ngwagwa
Regarding your comment on the 300Va being sufficient but no room for expansion could I fit bigger motors if I needed to or would I need to if the new set up get the most out f the current ones?
With 300Va then no you would need more current and 300Va limits you to about 8.5A total which could be borderline with some motors, with the current ones you probably won't have any trouble. But if one dies on you then you'll struggle to get the same size and it would be the ideal time to upgrade and 300Va would limit this.
Quote:
Originally Posted by
ngwagwa
As to using what I can I was assuming that with a new motion controller, PSU and drives apart from the 5 & 24V transformers everything else would be redundant bar the mains on/off switch.
Ermm not really you will still want some safety involved so a few relays will be needed for a hardwired latching E-stop system that safely Kills drives etc and lets the controller know there's been an emergency Stop.
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Re: Losing steps/position, again
ngawagwa: Jazz offers some good advice but you still have the problem that down-time is costing you money. From what I read you're still in the "misbehaving" stage and trying to get going? The original Denford electronics were, I understand 24VAC (and only 100VA for the drivers), but you say that somewhere along the line someone has replaced a bunch of stuff with a Mach3 conversion - including a separate 24VDC PSU. It's possible that they've pushed this straight onto the existing Denford card (it is likely to just rectify/smooth this straight onto the drivers and this would work with DC).
I offer the following cautiously, because it's a poor half-way house. If you need to try to get going quickly and don't mind a bit of down time to re-wire, then your original idea of slaving the DIV-268 onto the X-Axis could be sensible - and I can gift you a 200VA/36V SMPS. Yes, it's entirely the wrong PSU, but for a single axis (to test that the concept is right and you that have nothing else going wrong) it could get you going for the very short term. I can even drop you a couple more DIV-268s if they're handy for you (they are not great, but at 36V will out-perform the Denford drivers). That would just be to solidify you're own view as to what your shopping list needs to be and possibly get you back cutting tomorrow (if you don't remember my name - if you recall the vacuum bed? - I'm local). The PSU did, once upon a time, control a Denford star mill.
It's absolutely not an end-solution - I'd agree with the previous sentiments that you need to throw 300-500VA at around 50V at this with a toroid. Your final choice of drivers may allow you a simple direct connection to a transformer (if they support AC supply) and a modern digital driver will outperform the old shite analogues (and I include the DIV-268s amongst those). And you'd need to weigh up the down-time of slaving an axis onto a separate PSU and driver (an hour?) against your productivity. But the offers there.
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Re: Losing steps/position, again
I will getthe photos tomorrow.
And never thought about the E-stop either but there is at least one relay in there :)
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Re: Losing steps/position, again
Doddy, that sounds like a decent plan and I will take you up on it. I already have a DIV268 doing nothing so I won't be needing that thanks. It may take e a little longer than an hour as I have no idea where the current X axis is fed from, maybe it will be apparent when I get behind the bits added for the conversion. When would it be convenient to pick up the PSU?
Thanks
Carl
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Re: Losing steps/position, again
Quote:
Originally Posted by
ngwagwa
When would it be convenient to pick up
Sent a PM.
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Re: Losing steps/position, again
Quote:
Originally Posted by
JAZZCNC
If you go with the AXBB and UcCNC software then you won't be able to use it and I would use the UcCNC software over Mach3 as it's getting long in the tooth.
.
Looks like I can use a plugin to control the VFD http://www.forum.cncdrive.com/viewtopic.php?f=14&t=2041
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Re: Losing steps/position, again
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Re: Losing steps/position, again
You've linked to the same file for each image.
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Re: Losing steps/position, again
Quote:
Originally Posted by
JAZZCNC
That's WRONG information your giving out, the drives don't regulate the voltage they regulate the current. 70Vac which is 98Vdc would destroy those little motors in no time at all. It would also make them run like a bag of shite.
You cannot stick any voltage you like into a stepper, there is a limit where it starts to have very negative affects. Namely iron losses and motor heating which kills them.
Those Large voltage Ac drives are only really any good for larger steppers Like Nema 34 or very high inductance NEMA 23's. Your typical 3-4Nm 4.2a Nema 23 with 3-4mh inductance doesn't like to be run much more than 80vdc and at that, you are pushing them past there design threshold so are shortening there life.
For the NEMA 23 motors, which this machine will have fitted he'll only need drives with a max rating of 70Vdc and would run them around 55-60Vdc. Or 50Vac drives running at 40-45Vac.
Steppers are generally all rated 2-3Vdc yes?. So if said nema 17 / 23 or 34 (2-3Vdc) were put on the same driver why would I only blow the 17? (unless I didn't change the current output).
Also inductance. There are Nema 34's out there that are abysmal running on 60V supplies and ideally need at least 120Vdc to work reliably.
Also there are now drivers on the market with direct 240Vac input connections so no need for psu's anyway. These are aimed at nema17-23 size. Why would these not burn them up either?
I and many others use 60Vdc at least using larger 34 size drivers to run nema17 & 23 size motors. Even that goes against the grain and it's worked for years.
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Re: Losing steps/position, again
Um!, no 5V supply to the BoB?, normally people sling a USB lead from the computer to the BoB, and the BoB salvages a 5V supply from that. Or, you can provide a 5V supply to the "PC 5V" supply on the board itself.
Edit: My bad, image 4A shows the BoB has a supply from somewhere.
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Re: Losing steps/position, again
Quote:
Originally Posted by
Doddy
Um!, no 5V supply to the BoB?, normally people sling a USB lead from the computer to the BoB, and the BoB salvages a 5V supply from that. Or, you can provide a 5V supply to the "PC 5V" supply on the board itself.
Edit: My bad, image 4A shows the BoB has a supply from somewhere.
I've got a similar BOB and spotted something too.
If you take your 5v from 'elsewhere' (bottom right of bob) and don't get it through the usb header it bypasses the boards protection circuits!! Caution needed.
It's recommended to use a bare ended usb cable from a psu to the board header in order to both avoid PC usb noise and keep board protection.
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Re: Losing steps/position, again
Quote:
Originally Posted by
Doddy
Um!, no 5V supply to the BoB?, normally people sling a USB lead from the computer to the BoB, and the BoB salvages a 5V supply from that. Or, you can provide a 5V supply to the "PC 5V" supply on the board itself.
Edit: My bad, image 4A shows the BoB has a supply from somewhere.
I think it is fed from the Baldor board behind it - it's the top red wire
https://lozharroplures.co.uk/my_images/10.jpg
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Re: Losing steps/position, again
Quote:
Originally Posted by
ngwagwa
See my previous post on this. I have same board.
