[john-100]

Hi Lucas

looking at the IR2104 data sheet I agree with your comments

its a good idea to change the drivers as well as the FETs

HI Dave

I've added the component values to this diagram :-

Attachment 262734

John

[lucas]

I'm not sure that the driver chips will be bad, depends on the supply voltage used. Measuring the outputs with a DVM in diode setting might give an indication.
To be sure a scope is needed, replacing these SMD parts without the proper tools isnt' easy without damaging the PCB.

That big resistor is a wild guess, can't see the tracks and the colour code (black, brown, black, silver...) doesn't make sense, could be green, brown....

[john-100]

Hi Lucas

working from photos isn't ideal ,but after increasing the saturation the 1st & 3rd bands still look the same colour !

looking at the photo the resistor marking looks like black , brown , black , silver , brown
this decodes as 0.1 ohm 1% using this calculator :-
Resistor color code calculator - 3, 4 and 5 band resistors


the resistors I normally use conform to this :-
5 Band Resistor Color Code Calculator and Chart – Online Conversion Calculators | DigiKey Electronics

an easy check will be to measure the resistor in a working driver

with the KL 8056 motor current set to t maximum what do you expect the average supply current to be ?

if the resistor is 0.1 ohm resistor 0.6W , assuming I've estimated the size and read the resistance correctly
the maximum RMS current will be 2.45A (If the run it to its limit)



John

[skyguynca]

Ok, so now I need some help in what you said John and Lucas. I need to check the IR chips, but I am not really understanding how to check them.

[lucas]

This measurement will give a good indication but not a 100% good/bad one.
It's best to do this with all mosfets removed, the shorted ones MUST be removed or the measurement is useless.
To remove them easily without damaging the PCB: cut the pins and remove the remainder of the pin from the hole.

There are 8 measurements for each chip, set the DVM in diode mode and measure in 2 directions between the following pins: (similar to the mosfet measurement you did before).
One direction should read open and the other a low value, this should be the same between all 4 chips.
Pins: 1 - 5, 5 - 4, 8 - 7 and 7 - 6.
Example: red lead on 1, black on 5. Value for chip 1, Value for chip 2, Value for chip 3 , Value for chip 4.
Next: black lead on 1, red on 5. Value for chip 1, Value for chip 2, Value for chip 3 , Value for chip 4.
Next: red lead on 5, black on 4. Value for chip 1, Value for chip 2, Value for chip 3 , Value for chip 4.
etc..

OK, a little brainfart with the color codes mixing 2 and 3 band ones. That 2.45 Amp looks ok but with a fully loaded motor, it will be much lower on a bench test.
I would set the current to the minimum value (0.5 A) for testing and the supply current limit to 0.5 also.
In the absence of a lab supply: use a small DC adapter 24 - 30VDC 0.5 to 1 Amp max.

[skyguynca]

Got it, will do it tomorrow and post the results

[john-100]

Hi Dave

just to add to Lucas's post , a diagram of the driver chip function and pin out :-

Attachment 262830


John