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Asked — Edited

Weak Thumper 4Wd

I'm trying to build a mid-size robot using the Thumper 4wd and two 2.5 Amp motor controllers and 12v/12Amp battery to run it but I don't have torque to turn it around (only to go forward/backwards).
Actually I can easily stop the wheels with my hands. However if I will connect the motor directly to the battery I can't stop it from turning.
So my guess is that the 2.5 amp is not enough or something is wrong.
There is any quick fix for that on the 2.5 amp controller or should I get a new motor controller? Or. I'm pushing the unit to the limits


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Yes.. Usually when you connect a new servo to a good ezb the servo will move slightly but now it will not do anything.. So I suspect it's something with power or something like that
Sounds like the LM1084 voltage regulator is dead. You will need to get an EZ-B PCB without chip and bluetooth. Just the board, and swap your components over. To get that, you'll need to Contact Us.
DJ, i think you are right. I also believe that it's the LM1084.
Can i just get a new LM1084 and replace it with the defective one? Also, what will make the LM1084 to fail? It was working fine for some time and then suddenly it failed during programming.
Could it be that the 12v 12ah battery was too much for the EZB?
Ok, so nothing has changed after replacing the LM1084 voltage regulator with a new one.
I can connect to the EZB board (even upgrade the firmware) but I cannot send any servo movements nor get any feedback from any of the sensors connected to it.
Any idea what else I should replace to make the EZB alive again?
By any chance do you have some LEDs sitting around? Connect your ezb and you should have solid led on the board and bluetooth status lights. A quick way to test your signal pins is to use a servo ext cable and solder long lead to pos and short to neg. Plug it into a port on ezb and then use the pwm slider. Choose that pin number and turn the slider up , if it blinks faster till it gets solid as you turn the slider up then that port is working properly. Test all your digital out pins this way.
Also I would delete the Bluetooth profile for the ezb and uninstall then reinstall ARC just in case the software interface had been corrupted by a bad sector on your hard drive just to be sure.
Thanks for your LED suggestion. I will give it a shot.
The EZB is connected directly to the computer with a USB TTL cable. I have tried different computers but got the same results.
I will remove it and connect the Bluetooth again to see if it changes anything.
So, after replacing the LM1084 a few times, checking every component and putting back the Bluetooth module, the EZB is still dead.
After tracing every part i realized that there was no voltage passing to any of the digital ports. So my conclusion is that there is a problem in the PCB connection somewhere between the layers.
By creating short-circuit and connecting the 5V directly I managed to successfully bring the EZB back to life.
Finally I can continue with the development. yahhhayy
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Well I'm glad to hear you got it back up and running!:)
United Kingdom
Great bit of fault finding I must say. However be careful as I would say you have burnt out a land somewhere on the EZ-B board and as DJ said it looks like the EZ-B was providing power to the motor controller not the batteries.

Can you post a diagram of your wiring?
Sure, I will make the wiring diagram.
I still want to make this monster turn on a carpet.
United Kingdom
Good in the meantime dont stall the motors with your hand you may overload something again. I take it they are geared motors on the wild thumper chassis?
This is my wiring diagram, I don't see how the EZB will be damaged by this setup unless I'm missing something here.
It is functional. However, it's very weak and cannot turn on carpet even with new indoor wheels.
If I will just connect the battery directly to the motors it will make it work very hard with plenty of torque, it's like the h bridge is not providing the required amps to the motors.

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I didnt realise you had 2 H bridges? others can comment if they are wired correctly I only have 2 motors on my H bridge

I would disconnect the 5Volt supply from the EZB but make sure there is a ground wire back to the board and see what happens then. If its taking power from the EZB and not the 12 Volt supply nothing will happen. Then you can check the setup of the H bridges.

Also try just one H bridge by completely disconnecting the other one
Hi Robotdude,

I have the Thumper 4WD and I am using the same setup as you with the 2 H-bridges from the EZ-Robot store. It works fine for me, but I don't have anything heavy loaded on mine. Just some sensors. I usually run the H-bridges at 50% of power to get a reasonable speed for indoor use. Did you make sure that your batteries both have a common ground?

Also, can you post a diagram of the other wires you are using for the digital connections from the EZ-B?

Finally, what "indoor wheels" did you buy? I am trying to find some for mine.

With the big outdoor wheels I found that turning on a carpet was very difficult. In order to execute a turn I had to use a custom Movement Panel and set the speed on one side equal to about 20% of the speed on the other. For example, to turn right, I set the right-side wheels to 10% power and the left-side wheels to 50% power. That seems to work best.

Hi Mike,
My robot weight around 9kg and everything is connected to the same 12v battery so there is a common ground.
I wired the digital ports similar to http://www.ez-robot.com/Community/Forum/posts.aspx?threadId=2745
So I combine the wires together to save ports on the EZB
I used a very simple kid's bicycle training wheels with some small modification to make it fit into the motors.
Are you sure that the 2.5 amp h bridge are enough for the Thumper 4wd? Why if I connect the battery directly I will get more torque? That shouldn't happen if the h bridge is strong enough no?
I think the main difference between my Thumper and yours is the 9kg of load on yours. I can assure you that I only need 50% power with the h-bridges to go pretty fast around my house. But I have almost zero load. So I haven't tried it with a large load .

What wheels did you buy for inside use?