Hi!
Anyone tried the 2DM860H chinese controllers?
Any good? :cower:
They probably cant beat the AM882 or EM806, Im aware of that.
But a damn bit cheaper :beguiled:
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Hi!
Anyone tried the 2DM860H chinese controllers?
Any good? :cower:
They probably cant beat the AM882 or EM806, Im aware of that.
But a damn bit cheaper :beguiled:
Aaaw come on, doesn't anyone have experience?
It might just be an dm860 in a new box :D
Nope....AM882 only for me sorry.....
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I know I should go the same route. But the cost makes me look around hehe
Thing that persuaded me was they were tried and tested by others. My machine was cutting acetal plastic all day today and just doesn't miss a beat...priceless 😁
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Why not buy some and review them for us? :DQuote:
Originally Posted by Nr1madman
I've learned that cheap parts often aren't the cheapest way ;-)
Haha I know that this is good advice :DQuote:
Originally Posted by magicniner
But Im leaning towards the am882 because of the stall detect. I will be using 2 motors for x axis and it would be disaster if one was stalling..
Deep inside I know that this is the wrong place to save £50
I had to try these :D
Call me an idiot but who knows. .they might work just fine hehe
How should the dip switches for current be adjusted? Peak current or RMS current?
On the drivers there are rj45 jacks.. I wonder if there are some software for tuning?
Got no manuals so I think I'm gonna search the Web for something useful :)
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Starting to see why "cheap" isn't always Cheap? :DQuote:
Originally Posted by Nr1madman
Haha I know, I know!Quote:
Originally Posted by magicniner
Found the manual online atleast :D
It actally had info about the connector I wondered about. Was serial connection for parameters. :) Have to look up what kind of software to rule this thing!!
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Alrighty!
Might be an idiotic buy after all ;)
So.. current configuration? Should I match peak or RMS settings on the dip switches?
Have 4amp motors (4nm nema23 from cnc4you)
If going for RMS setting for the driver I get 3.42A RMS 4.78A peak.
If going for peak current I get 3.15A peak 2.15A RMS or a slight overshoot at 4.03A peak 2.88A RMS.
For me this seems like really bad options for maximizing my motors.
I know the AM882/EM806 have software options for fine tuning current but this driver does not seem to have this.
So.. what says the experts? :D
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I'd set the drives to 4 amps peak?
Thanks Ger!Quote:
Originally Posted by Ger21
Will try that ;)
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I would read the data sheet and set the current to something reasonable. That is science.
Once the machine is running, adjust it so that the motors run at a temperature that is just about as hot as you can comfortably hold, which is around 60C. That is engineering...
Seriously, stepper motors are designed to run hotter than you might expect. More current gives better performance as long as you do not overheat them. Those current readings are really only a guide or a rough starting point, not absolute limits. Remember to set the stationary holding current to half (usually a dip switch setting) which helps keep them a little cooler while not moving.
This is just what I wanted to hear!Quote:
Originally Posted by Neale
Thanks!
I realise why they mark up both peak and RMS current. But it's still misleading when you want a safe maximum ;)
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Hi Nr1madman,Quote:
Originally Posted by Nr1madman
What is the verdict on the drives?
Grtz Bert..
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Oh let me get back to you in a couple of months :DQuote:
Originally Posted by driftspin
Im just starting to learn my router.
What I do know is that they move my motors and I haven't had any issues (yet). Would the machine move faster/cooler/quieter with am882s.. I have no idea!! :)
I bought 2 drivers first with the plan of buying 2 am882s for my dual motor axis but in the end I ordered 2pcs of 2dm860s more. The first two I got had metal casings. The last two had metal bottom and heatsink but plastic cover :)
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I've just got 4 to use on a machine so I'll tell you the difference.!Quote:
Originally Posted by Nr1madman
Awsome! Thanks ;)Quote:
Originally Posted by JAZZCNC
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Hi JAZZCNC,Quote:
Originally Posted by JAZZCNC
It would like to know too...
Grtz Bert.
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Real world experience. Tonight I burnt out a stepper (my fault, overdriven on current setting). In doing so it took out the 2DM860H.
Not only on a Sunday, but a Sunday in the middle of a global pandemic.
Got a couple of spare steppers (higher rated) and I can slave the A-Axis controller, but PITA all the same.
The conspiracy theorists and trumps of this world would say the Chinese did that on purpose..:toot: . . . . Me you just been bloody unlucky mate because it takes a lot to burn out stepper in my experience.:encouragement:Quote:
Originally Posted by Doddy
Unlucky?, no, just stupid. I've slaved (via changeover relay) two machines off one set of drivers (with an switching interlock to protect the drivers from disconnection) to save on space and cost. But in doing so I'm driving 40 year old 2.1A steppers at rather higher than they're designed for, so, in honesty, it was waiting to happen. Interestingly the B coil shorted and destroyed the driver - to the point that, from what I can tell, the whole logic is fried - I could understand the power output being destroyed, but to have no LED fault indication was a surprise. But, live and learn - my replacement steppers are rated higher (I'd already replaced the X-axis for more torque) - so all is good. It's just a buggeration to strip the controller down to replace the driver - might wait for a replacement rather than physically moving the A-Axis (depends if I can remember if I tapped the plate that they are mounted to - easy to swap, versus bolted-through in which case have to strip the mount plate out.Quote:
Originally Posted by JAZZCNC
Hey everyone!
Doddy, I feel your frustration!
Have been thinking about buying spare parts for my router so that if something like this happens I have parts availible "on the shelf".
That beeing said my drivers are still working great.
I usually run my machine 30-50hours per week depending on how many orders I have.
Have noticed resonance on some occasions when I have been running 10-12hours straight and push the feedrates up to get finished.
But that just tells me that my normal speed is optimal 😁
Aha, there's an onboard fuse that's blown... that's the first test (and those two replacement drivers I've ordered.... may eventually come in useful)
EDIT: Premature - that just blows fuses now, guess an output driver is shorted and is now just a fast-fuse-blower.
So where's the photograph with the lid off? Is the failed device replaceable with a soldering iron?
Photo?, okay...Quote:
Originally Posted by Kitwn
General board
Attachment 27889
Replaced (failed) wire-ended fuse with 20x5 fuse clips and placed a F10A fuse in to test, no motor. Blew fuse
Attachment 27892
Difficult image to take, but shows at leasts 7 devices soldered to board and bonded to heatsink. At this stage, with two drivers on order, one for delivery tomorrow, my interest waned.
Attachment 27893
OK, take the point. But CMOS power transistors are a few pence each and it would be a shame to trash the whole unit if they're accessible for easy soldering.
You're right, and maybe a bit of a tear down could be useful for the wider audience.
Okay, so a bit of a tear-down of the 2DM860H.
Attachment 27900
Highlighted - 3 black screws that hold the board to the heatsink. 2 silver screws set into plastic top-hat isolators that secure the power electronics firmly to the heatsink.
Bottom left - 2 pin connector that is the AC/DC power input. This feeds through the fuse (normally a wire-ended... but what's there now is a bit of a hack attempt to repair. The big black circular thing is a NTC power thermistor designed to limit inrush current (it starts at high resistance but quickly drops as it warms up - likely used to allow the processor to start up and settle the power system before damaging anything.
Top left - I expect a small SMPS for the logic (untested). Left centre (left edge of board) - you can just see 4 pins for the power rectifier on the rear of the board Smoothing caps along the top and to the right of the board - all the logic. Thar be dragons.
Next pic, underside of the board, and a load of power devices...
Attachment 27901
The big thing at the top is the bridge rectifier. Four pins, which you can't see because of the thermal washer on it, but these are '-', '~', '~', '+", from left to right as orientated in the image.
The 8 TO220 packages are IRF640N N-Channel MOSFETs.
Parallel, and to the right of the top four of these are the stepper driver connections, labelled (top to bottom) "B-", "B+", "A-", "A+". If you look at the 8 MOSFETS, there's 4 pairs, vertically aligned. The left-most is driving the "B-" stepper; to the right of this drives the "B+" phase, then the "A-" and the "A+"
Each pair of MOSFETs are half-bridge configuration, and two pairs makes a standard H-Bridge for each stepper winding. The four pairs driving the 2 windings on a standard 4-wire stepper.
Attachment 27902
And a rough-order board layout...
Attachment 27903
Now, if, like me, you've blown one of the controllers up, chances are the problems are with these two H-Bridges, and the easiest method of diagnosing the problem is just measuring for shorts from pins to ground. Clearly, the bottom four MOSFETs will each have their Source terminals connected to ground (and the top fop have their Drains connected to V+)
I quickly tabulated a few measurements.
Looking at that, I reckon MOSFETs M1 and M6 are blown. M2 is suspect, but I think the low resistance source-to-ground is via the internal short on M6 (M2 source, connected to M6 drain, which is near-short-to-ground).Code:Rg-d Rg-s Rg-0 Rd-0 Rs-0
---- ---- ---- ---- ----
M1: 1R 1R 4k 600k 2.6M
M2: 20k 20k 20k 600k 17R
M3: 2.6M 20k 3M 600k 6M
M4: 2.6M 20k 3M 600k 5M
M5: 20k 20k 20k 500k 0R
M6: 20k 2R 1R 18R 0R
M7: 2.6M 20k 20k 3.2M 0R
M8: 2.6M 20k 20k 3.2M 0R
The MOSFETs are through-hole devices, although I has a solder rework station I'll just crop each leg off the device, apply tension with some tweezers and heat each pin one at a time with a soldering iron to remove each pin. Solder-wick each side of the board clean, then remount and solder in from the reverse side of the board.
I do have one IRF620, but the Rds for this is too high and Id too low (5A); and a bunch of IRF3205's but the Vds for these is too low (50V). So, I'll order a pack of IRF640Ns, and replace at least M1 and M6. And report back on the robustness, or lack therein of the 2DM860H.
Doddy,
That's a brilliant job, thank you!
I know most people want to just plug-and-play with modules but when you see how simple it is to fix some of the faults for yourself and realise how cheap some of the components are it saddens me to see people just give up and trash expensive modules that can be repaired for very little. Most faults with this kind of device will be in the power supply or output devices, all of which tend to be the large components that cost very little and are easy to replace as you've demonstrated. RS components will send you a bag of 5 new transistors for less than the cost of a pint, including postage!
A little unfair there - there's a long way to go before this works again, and I'm carrying cost and risk in repairing it - for some the downtime wouldn't warrant the cost of replacing with new. Also, to be absolutely honest, I don't think it's cost-effective for me to have spent trying to clear some form of metal debris from the fan supply solder pads for the last hour (finally resolved with a 0.4mm drill - which I managed to snap in the hole) - it was clear on inspection that the fan wiring was a bodge job with the assembler unable to poke the wire through the hole - silicone hides a whole multitude of sins on PCB assembly in china.
If it wasn't for this damned lock-down I'd throw the controller in the bin and be done with it, but being forced to spend time either with the wife or with a soldering iron, there's some curiosity value for trying to repair. But I do have some rather expensive tools to support that curiosity. Also for many in this game there's a lifetime of experience of feed rates and chip loadings that I just don't claim to understand, but then I wouldn't expect them to understand the behaviour of a h-bridge and failure modes of a MOSFET.
Horses for courses.
(but I'm determined now to get this sucker working again)
My apologies if I've sent you down a rabbit hole you were not intending to follow! On the other hand I think it's worth pointing out that many equipment faults can be repaired with a few tools which, once bought, will last for many years. There are more choices available than bin-and-replace for those willing to learn a new trick and I suspect you, like me, have reincarnated more than one piece of expensive electronics by knowing how to recognise and replace a faulty power supply capacitor costing mere pence.
If it were me I'd be bringing the soldering iron onto the dining table which is surprisingly close to my wife's weaving looms so I don't have to make your difficult domestic choice:welcoming:
The obvious question to ask is why, if there was a fuse, it was not accessible from the outside for replacement purposes? The answer, I think, is for the same reason that I don't stick fuses everywhere in my own control box. The fuse in this case did not protect the mosfets - it protected the rest of the upstream wiring and power supply from a potentially dangerous overcurrent situation causing a fire. Pound to a penny that the mosfets popped first, then the fuse blew to protect the rest of the system. The manufacturer knew this - no point in a replaceable fuse if the driver is dead anyway. Fuses are very important and shouldl not be forgotten - but just remember what they actually achieve and use them accordingly.
On a more positive note it's interesting to see that these drivers use well-marked and easily available replacement mosfets, although I would be a bit hesitant about working on through-hole boards - haven't had to do that myself.
MOSFETs due in tomorrow from Farnell... along with some other goodies. Neale - that's pretty much the purpose of a fuse - and anyone relying on one to protect semiconductors has a lot more optimism than me. The more I look at these drivers the more I like about the design - the accountants haven't got too close to these, just close enough to the training of the assembly workers :)
Neale,
When I was a lad power transistors (at least the radio frequency ones) were described to me as "the fastest fuse on three legs". In practice these things often fail as a short circuit which is what takes out the fuse to protect everything else as you say. Doddy's got an evening amusing himself with his soldering iron out of it so all's well that ends well.
Putt's Law states that technology is dominated by two types of people. Those who understand what they do not manage and those who manage what they do not understand.
I seem to have many things amusing myself at the moment. Ho-hum. I like Putt's Law, I need a coffee mug with that on it.Quote:
Originally Posted by Kitwn
My degree, best part of 50 years ago now, was in electronic engineering - this at a time when a quality "transistor radio" was still populated with germanium transistors. I remember the same quote! My son once borrowed my variable-voltage bench power supply to charge a car battery. Not a good idea. At least 2N3055s are big enough to get a decent size soldering iron on! 6 of them, as I recall...Quote:
Originally Posted by Kitwn
I cut my teeth on AC171s
Edit: my bad, AC181s.... twas 45 years ago.
50 years ago was about when I got my Philips Electronic Engineer Set for Christmas. And look where that got me!
AC181s......You were lucky! I actually preferred playing with BY1144s but that came later.