A couple of members have bought these boards and experienced problems using them above 24v... due to exploding TB6560 chips. I note that there are some further cases documented on CNCZone.
After researching the chips and the circumstances under which they were used I suspect the TB6560 chip is susceptible to transients, particularly back-emf from high inductance motors, leading to catastrophic failure.
The majority of circumstances where the problems have occurred have been with motors having inductances >10mH in the configuration they were wired and with supply voltages >24v (typically 30v).
I have noted elsewhere (CNCZone) that there is some debate about the quality of the protection diodes, certainly the part numbers suggested make these unlikely to be much use.
There is a note on the TB6560 datasheet which is telling:
If your design includes an inductive load such as a motor coil, incorporate a protection circuit into
the design to prevent device malfunction or breakdown caused by the current resulting from theinjury, smoke or ignition.
inrush current at power ON or the negative current resulting from the back electromotive force at
power OFF. IC breakdown may cause injury, smoke or ignition.
Use a stable power supply with ICs with built-in protection functions. If the power supply is
unstable, the protection function may not operate, causing IC breakdown. IC breakdown may cause
The failure often occurs on switch on, but it is likely that the damage is being done at switch off. It is important that the driver board is disabled and the motors are not powered before switching off. You need to ensure that the PC is driving a suitable ENABLE line from the software that will power down all motors before you turn off the supply to the board. And ensure the PC is on and the enable line stable before powring up the driver cards.
In short, these boards are a cheap option and will work OK as long as you stay inside the 24v power supply limit. Also note that the maximum current limit setting on the board is fixed at 1.5A, not the 3A stated in the ads. It is possible to run these at 3A by reducing the on-board resistors but they need better (faster) protection diodes.
Note, despite what the supplier may say, the voltage is NOT a function of the size of motor - it makes not a jot of difference what size motor frame you are using (NEMA17, 23, 34), its the inductance of the motor and the supply voltage that matter.
thanks for all your time you put in this
im waiting to get an e-mail from the chap i keep you posted
the psu i got from ebay is 360w 24v upto 42v it says it douse
nope maximum 38v 2 moltimeter tested it
oh why nothing seems to be correct i buy lol
model number fdps-360a
What did they say elecom ?
thanks for all your time
there going to replace the burnt out chip and pay for postage two and from there place
i asked them to change the 4 chips but no replay
so im posting out on monday air mail to china
hope there give me new board
its fun trying to find a box to send it in
i glad i keep my old boxes (wing commander 3) will do nicely give him some history lol
OK, Mariss over on CNCZone (of Gecko fame) has posted some thoughts which concur with my views on this... these boards are really only good for 1.8A and 30v maximum, IF you have a decent smoothing capacitor on the power supply (he recommends at least 1000uF and I'd suggest 2,200uF as a minimum - for more info read the thread here) If you are testing on a single axis and a switched mode PSU with no additional capacitor then beware as there is nowhere for the back-EMF energy to go.
I have purchased on e of these boards. They give two options, one at max 3.5amp and one at max 2.5amp. I picked the lower one as I want to run 0.5amp steppers. Do you know what the difference in electronics is between the two.
If you have details of the pin connections for Kcam, they would be very welcome.
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