Use PWM to control your Jebao DCT pump using brushless motor controller from ebay
- Thread starter d0ughb0y
- Start date
theatrus
100-mile-commuter
Just for grins, I made a drawing of the major features of the 50W Jebao controller board:
I can put up a DXF or similar file. How different is the larger pump PCB?
All dimensions are mm (since 95% odds it was designed in metric). The mounting holes are all 3mm (M3). The square features are the 1206 LEDs and the 6mm square buttons, respectively. The heatsink would be on the back side of the board from this view, and measure 28mmx41mm
I can put up a DXF or similar file. How different is the larger pump PCB?
All dimensions are mm (since 95% odds it was designed in metric). The mounting holes are all 3mm (M3). The square features are the 1206 LEDs and the 6mm square buttons, respectively. The heatsink would be on the back side of the board from this view, and measure 28mmx41mm
d0ughb0y
Active member
I replaced some parts and it sort of worked.
It ran in forward direction at 36 watts, so that's good news that it at least matches the stock controller. But it does not start most of the time. I think the reference signal is too weak to generate a good LM339 output.
There is one more difference, the stock controller powers the LM339 at 18v and the bemf voltage divider drops the output voltage down to 8v. The ebay controller LM339 is powered by 5v and the bemf is voltage divided down to about 2v.
I'm guessing if I change the voltage divider value or even power the LM339 at 18v like the stock controller, this will be able to startup the pump every time.
red arrow points to the replacement resistors, it replaced capacitors that were there originally.
I am thinking now the best way to proceed is to build a controller from scratch.
It ran in forward direction at 36 watts, so that's good news that it at least matches the stock controller. But it does not start most of the time. I think the reference signal is too weak to generate a good LM339 output.
There is one more difference, the stock controller powers the LM339 at 18v and the bemf voltage divider drops the output voltage down to 8v. The ebay controller LM339 is powered by 5v and the bemf is voltage divided down to about 2v.
I'm guessing if I change the voltage divider value or even power the LM339 at 18v like the stock controller, this will be able to startup the pump every time.
red arrow points to the replacement resistors, it replaced capacitors that were there originally.
I am thinking now the best way to proceed is to build a controller from scratch.
Last edited:
karimwassef
Active member
I replaced some parts and it sort of worked.
It ran in forward direction at 36 watts, so that's good news that it at least matches the stock controller. But it does not start most of the time. I think the reference signal is too weak to generate a good LM339 output.
There is one more difference, the stock controller powers the LM339 at 18v and the bemf voltage divider drops the output voltage down to 8v. The ebay controller LM339 is powered by 5v and the bemf is voltage divided down to about 2v.
I'm guessing if I change the voltage divider value or even power the LM339 at 18v like the stock controller, this will be able to startup the pump every time.
red arrow points to the replacement resistors, it replaced capacitors that were there originally.
EXCELLENT!! We can use these controllers with a few component changes!
Wait - what? Confused.
karimwassef
Active member
whew.. you know I have 4 of these green boards 
d0ughb0y
Active member
now that I'm not taking a video, it starts every time again.
Anyway, I'll hook up the lm339 signals to an oscilloscope to see what is going on and maybe figure a way to get this to work all the time in water.
I just put the pump back in the water, and now it starts pretty much all the time. I think only once or twice it did not start out of maybe 20 tries.
and it is definitely putting out more flow than before the mod. maybe even same as stock, although it is hard to quantify visually.
Anyway, I'll hook up the lm339 signals to an oscilloscope to see what is going on and maybe figure a way to get this to work all the time in water.
I just put the pump back in the water, and now it starts pretty much all the time. I think only once or twice it did not start out of maybe 20 tries.
and it is definitely putting out more flow than before the mod. maybe even same as stock, although it is hard to quantify visually.
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theatrus
100-mile-commuter
Use PWM to control your Jebao DCT pump using brushless motor controller from ebay
Possible the new motor controller doesn't have a long enough open loop period to get things going, so the lack of a strong BEMF signals breaks it. Or the ramp is too fast for the pump.
What's the new capacitor/resistor value vs the old?
Possible the new motor controller doesn't have a long enough open loop period to get things going, so the lack of a strong BEMF signals breaks it. Or the ramp is too fast for the pump.
What's the new capacitor/resistor value vs the old?
karimwassef
Active member
I would say that if it didn't always start, a smart controller can detect and restart.
Unfortunately - it depends on why it's not starting...
Sometimes, if the starting pulse isn't strong enough AND the motor phases are at the most distant state (trough of the flux distribution), the motor won't start. It's a random event and not easily reproducible.
In that case, we need to increase the starting drive.
Unfortunately - it depends on why it's not starting...
Sometimes, if the starting pulse isn't strong enough AND the motor phases are at the most distant state (trough of the flux distribution), the motor won't start. It's a random event and not easily reproducible.
In that case, we need to increase the starting drive.
d0ughb0y
Active member
This is the original BEMF circuit. I only show 1 of 3 op amp circuit. The other 2 are identical to the first one.
I removed R3,R4,R5,R6,C2,C3,C4
The resistors are near the pcb edge next to the LM339.
The capacitor locationss are as shown in my earlier post.
solder 10k 0603 resistor in place where the capacitors were.
The new circuit use the voltage divided MA signal, all 3 tied together and fed to REF input of all 3 op-amps. This is essentially the bemf circuit of the stock controller (with some minor difference).
You need a good magnifier and a hot air rework station to do this mod.
links to youtube video so it shows on tapatalk
https://youtu.be/Hf0qnLADyWg
https://youtu.be/LKvdTXJ5HiQ
I removed R3,R4,R5,R6,C2,C3,C4
The resistors are near the pcb edge next to the LM339.
The capacitor locationss are as shown in my earlier post.
solder 10k 0603 resistor in place where the capacitors were.
The new circuit use the voltage divided MA signal, all 3 tied together and fed to REF input of all 3 op-amps. This is essentially the bemf circuit of the stock controller (with some minor difference).
You need a good magnifier and a hot air rework station to do this mod.
links to youtube video so it shows on tapatalk
https://youtu.be/Hf0qnLADyWg
https://youtu.be/LKvdTXJ5HiQ
Last edited:
karimwassef
Active member
Ok. Different direction for a minute...
I'm experimenting with reverse flow through DC pumps, so I have one pump working normally and the other "off". The second pump line acts as a "drain" while the main pump is on. I didn't think much of it, until I noticed that the "off" pump's controller was flashing - as in a fault mode.
How can that be... There's no 24VDC on it. Sure enough, disconnecting the input power didn't stop it since the off pump's impeller was rotating due to the reverse flow and generating enough voltage in the power board to trigger the fault mode flashing lights.
Question - if I let this happen regularly, will I fry the controller?
This is the native Jebao controller.
I'm experimenting with reverse flow through DC pumps, so I have one pump working normally and the other "off". The second pump line acts as a "drain" while the main pump is on. I didn't think much of it, until I noticed that the "off" pump's controller was flashing - as in a fault mode.
How can that be... There's no 24VDC on it. Sure enough, disconnecting the input power didn't stop it since the off pump's impeller was rotating due to the reverse flow and generating enough voltage in the power board to trigger the fault mode flashing lights.
Question - if I let this happen regularly, will I fry the controller?
This is the native Jebao controller.
theatrus
100-mile-commuter
The pump is now an alternator, and the body diodes in the FETs are acting as your rectifier. It's probably not going to be too terrible unless the speed got really high.
The best solution would probably be braking the impeller - having a controller which can hold the impeller is an electrically braked position (power on).
karimwassef
Active member
I actually like having the reverse water flow through the pump. It flushes any debri back out. It's not the only drain, of course. But how can I tell if I'm stressing the controller?
A middle path option here would be to let it run in reverse for a minute & then brake or run in very low output mode.
A middle path option here would be to let it run in reverse for a minute & then brake or run in very low output mode.
theatrus
100-mile-commuter
Stalling the impeller shouldn't dramatically change the reverse flow.
I need to trace out some more of the circuit to determine what else is powering up or if it's only looping back through the main power rail (the back EMF circuit is all high enough impedance from the looks of it). There is a ceramic cap and a big electrolytic on the rails so transients shouldn't be an issue.
If you check the voltage on the DC jack when it's in this mode, how high does it get? Probably at least 6+V to power up the main controller MCU (which I still suspect is a PIC, but haven't checked the header next to it).
If there is no real load, I don't think you're causing much damage. The FET body diodes aren't very robust usually.
I need to trace out some more of the circuit to determine what else is powering up or if it's only looping back through the main power rail (the back EMF circuit is all high enough impedance from the looks of it). There is a ceramic cap and a big electrolytic on the rails so transients shouldn't be an issue.
If you check the voltage on the DC jack when it's in this mode, how high does it get? Probably at least 6+V to power up the main controller MCU (which I still suspect is a PIC, but haven't checked the header next to it).
If there is no real load, I don't think you're causing much damage. The FET body diodes aren't very robust usually.
d0ughb0y
Active member
I think the stock controller has more flow than the green controller with the mod.
It looks like the ebay board controller does not do any kind of filtering of the bemf signal, unlike the stock controller where it knows to ignore the narrower pulses (probably a cpu program). It is still usable and viable option, with or without the mod, just less flow and if you only need the variable speed controllability without the bells and whistles.
I'm going to use the controller as it is for now. Once I finish my diy controller, I'll try to build a pump controller.
It looks like the ebay board controller does not do any kind of filtering of the bemf signal, unlike the stock controller where it knows to ignore the narrower pulses (probably a cpu program). It is still usable and viable option, with or without the mod, just less flow and if you only need the variable speed controllability without the bells and whistles.
I'm going to use the controller as it is for now. Once I finish my diy controller, I'll try to build a pump controller.
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