HDBB2 breakout board dead?

[cncdrive]

Hi,

I'm attaching a picture to this post.
You should check the Voltage with a multimeter between (I've marked the test points with light green color):

GND - point 1. : If there is no voltage here then you DC power input connection do not get in at all, maybe a lost connection or burnt up track on the PCB.
GND - point 2. : If there is no voltage here then the ferrite bead component whose pin is marked with point 2. is burnt. It is used like a fuse, it fuses out on heavy overcurrent.
GND - point 3. : If there is no voltage here then the reverse polarity protection diode whose pin is marked with point 3. is burnt.
GND - point 4. : If there is no voltage here then the 78l05 5Volts LDO is burnt and so it is not creating the 5Volts from the 12V input.

[cncdrive]

- It seems that there was an excessive current on the power input terminal caused the ferrit bead badly burn out. This can happen if you overload the outputs or something else damaged on the board causing excessive current to flow in this area.
- I don't know what caused it, so I can't answer the question.
- That ferrit bead acts as a fuse which burnt out.
- I don't know, since I don't know what overloaded the power input. One possibility is if your power supply gave an overvoltage damaging other parts which finally resulted a short circuit and the ferrit bead fused out, but I can't determinate if this was the cause or not, but I bet it was something else, e.g. excessive current on the output Mosfets.
- I don't know, because I do not know what have caused the issue.
- Your board is more than 1.5years old, we give 1 years warranty period, warranty covers manufacturing defects, this does not looks to be that. We could try to repair it though if you want us to do that, but not in warranty.

To see if there anything else damaged on the board or if only this component damaged you can shunt the burnt component.
I would do that for a test with a multimeter if it has a current limit then it would be safe to set the multimeter to current measuring mode and connect the probes according to that, set it to e.g. 0.5Amps current limit first and shunt that track out for a short time with the multimeter to see if the board comes to life or not.
If your multimeter does not have current limiting then you may use some wires and a fuse is also a safe way.

[cncdrive]

OK. I think that probably the issue was not the power supply, but there is still a chance that it was, it is impossible for me to know that.
And I see a high possibility that the board will still work if you just shunt out the burnt ferrit bead,
if it was just a temporarily heavy overcurrent on an output then the board will probably still work without problems.
But it is also possible that something else damaged and in this case shunting out the ferrit bead will not help.
I think it worth at least a try, because that damaged ferrit bead basicly do nothing else than fusing the board, so your board may still work without issues if you shunt it out...

[A_Camera]

OK. I think that probably the issue was not the power supply, but there is still a chance that it was, it is impossible for me to know that.
And I see a high possibility that the board will still work if you just shunt out the burnt ferrit bead,
if it was just a temporarily heavy overcurrent on an output then the board will probably still work without problems.
But it is also possible that something else damaged and in this case shunting out the ferrit bead will not help.
I think it worth at least a try, because that damaged ferrit bead basicly do nothing else than fusing the board, so your board may still work without issues if you shunt it out...

Looks like even the diode above the capacitor and the voltage regulator (or transistor) below are burned. Perhaps the cause of the issue is the capacitor. Not very uncommon that electrolytic capacitors cause issues, I'd check that out as well.

[cncdrive]

Hi Josef,

Electrolit capacitors failure mode is open circuit, so probably not the capacitor caused the issue. It is an LDO and not a switcing regulator.
It is possible that the diode died and that caused the ferrite to fuse out, but maybe the diode only got some smoke from the burnt out ferrite, it is hard to decide it from the picture, but could be verified with a diode tester.
It is also possible that the 5V regulator damaged, but that would mean that something else is damaged on the board which is now shorted out.

[A_Camera]

Hi Josef,

Electrolit capacitors failure mode is open circuit, so probably not the capacitor caused the issue. It is an LDO and not a switcing regulator.
It is possible that the diode died and that caused the ferrite to fuse out, but maybe the diode only got some smoke from the burnt out ferrite, it is hard to decide it from the picture, but could be verified with a diode tester.
It is also possible that the 5V regulator damaged, but that would mean that something else is damaged on the board which is now shorted out.

Hi,

No, unfortunately I have seen quite a few electrolytic capacitors which did not open on failure... but yes, I have also seen quite a few which blew their hat and also literally opened.
I don't know what you mean that it is not a switching regulator. No, it does not look like one, the one I meant looks like a 7805 or similar. I can't see what it is, I am sure you know better, but on the picture it looks burned, though it is not possible to say 100% just by looking at the picture.

[cncdrive]

Hi Josef,

I ment that it is a fact which is even tought in school that electrolits' failure mode is open circuit, this is not an opinion from me.
And this is because one armor is electrolit.
Unlike it is with tantaluum caps which failure mode is short circuit.

Ofcourse it is possible that it breaks down in short, but very unlikely and then at least the capacitor should become fat and mechanically damaged which does not seems to be the case as I see on the photo ... so it's possible, just not likely.

What I ment by "it is not a switching regulator, but an LDO" is that an LDO does not stress the capacitor like how a switching regulator does, so there is no high stress on that capacitor and so it is not a weak link.
Electrolits failure is often in switching regulator circuits, because the regulators using a PWM, but an LDO dropping voltage in a linear way, so no stress on the output cap. This is one reason why that cap is a standard one and not a low ESR one as you can see from it's blue color, if it was a switching step down converter then that cap should be a low ESR one with green or black color.
And yes, it is a 78l05 LDO, I wrote it in my first post in this thread.

[cncdrive]

Answering your questions in order:

- Don't overload and don't short out the outputs of the HDBB2.
- As said before it is a clear indication of an overcurrent event. It can be that the output Mosfets were overloaded or it is also possible that something else damaged on the board which caused a short circuit which overloaded the input which fused that component out. It is impossible to determinate which is the case without having the board here and making measurements on it.
- It can if it shorts things our on the board, it has to be conductive though, so the wood swarf has to be wet for that to happen.

Basicly all switching power supplies have current limits.
If the current limit is value low enough then it may protect the HDBB2 circuit, a well sized fuse on the DC power input wire works better though.