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DC Motor Driver Problem

endoramax

Jul 9, 2021
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Hi Everyone,

I am using this DC motor driver for my tennis ball launcher. When I was testing the machine on the outside one dc motor stopped after a while. I checked two motors that they worked as well. I tested the DC motor driver then I realized that there are no voltages in output. Also, I checked the DC motor driver there is no burn or damaged component on it.

I need to find a problem but I don't have enough experience in electronics troubleshooting. How can I check this card step by step?


WIN_20210708_09_16_48_Pro (2).jpg WIN_20210708_09_16_55_Pro (2).jpg

Best Regards.
 

Minder

Apr 24, 2015
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That appears to be one of those $2 - $3 version off ebay, usually a 555 PWM, You would need to do a little reverse-engineering of the circuit, i.e. draw it out on paper and go from there.
 

WHONOES

May 20, 2017
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I notice that it has a fuse on board. Is it intact?
 

endoramax

Jul 9, 2021
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That appears to be one of those $2 - $3 version off ebay, usually a 555 PWM, You would need to do a little reverse-engineering of the circuit, i.e. draw it out on paper and go from there.
Yes it is so cheap and I replaced them with a new one but I want to know why driver stoppped immediately. For example, problem is related to high power consumption (ampere) I need to change some components also I need to decrease the friction level so on.
 

Bluejets

Oct 5, 2014
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Only you will be able to check the current draw but I'm guessing it's more than the so-called rated current of 10 amp.
Probably popped the output element whatever that is.
More than likely a mosfet and again, more than likely the one on the large heatsink.
It's a wonder the fuse is intact, that sort of blows my idea out of the water.
 

Martaine2005

May 12, 2015
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I remember reading an ebay listing about a similar speed controller.
Something like "2A continuous with supplied heatsink and 10A with a larger separate heatsink". Not those exact words.
Also, to switch on with the lowest setting and slowly ramp it up.

What motor are you using? A 775 - 795 type? Even these small types can have a stall current higher than your rated controller.
And remember, each time a ball goes through your machine, it loads the motor heavily.

Martin
 

Minder

Apr 24, 2015
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What rating/value is the fuse?
You could try a fast-blow type if it does not cause nuisance blowing.
Or just drop the value.
 

bertus

Moderator
Nov 8, 2019
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Hello,

Sounds like the heatsinks are way too small.
Or it could be that the mosfets are not switched fast enough.
The time a mosfet stays in the linear region causes the mosfet to heat-up.
Also when mosfets are not driven all open (gate voltage to low) , heat will be the result.

@endoramax , Does the board have a voltage regulator for the 555?
If so, what voltage does it supply?

Next to the 555 pwm circuits, you will find circuits using the LM339.
Here is an example:
https://www.masinaelectrica.com/dc-motor-speed-controller-pwm-0-100-400hz-3khz-freq/

Bertus
 

endoramax

Jul 9, 2021
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Hello,


Or it could be that the mosfets are not switched fast enough.
The time a mosfet stays in the linear region causes the mosfet to heat-up.
Also when mosfets are not driven all open (gate voltage to low) , heat will be the result.

@endoramax , Does the board have a voltage regulator for the 555?
If so, what voltage does it supply?

Next to the 555 pwm circuits, you will find circuits using the LM339.
Here is an example:
https://www.masinaelectrica.com/dc-motor-speed-controller-pwm-0-100-400hz-3khz-freq/

Bertus

Hi

I am not sure the board has a voltage regulator vice versa. I supplied 24V but this time I supplied 27.4V (with lipo) for a short time. Could it be affected?

Thank you
 

Martaine2005

May 12, 2015
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I supplied 27.4V (with lipo) for a short time.
Did it work before with 24V? and now after 27.4V, it failed?

The item description says 12V - 40V input, so it 'shouldn't' be a problem. But I bought some 12V - 24V motors which exploded at 18V.

Martin
 
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