Capacitors help[PCB]

[Squish4058]

No idea where this goes on the forum, this was the best place I could find

 

I have a circuit board infront of me, suspected faulty capacitor in which the dielectric insulation has failed

 

I cannot confirm this, I have a multimeter? if its as simple as measuring resistance or something let me know

My current fix idea is to solder a Can based capacitor replacement above the surface mount (which I think is dead)
Wiring them in parallel

 

Now from what I understand, Wiring a good capacitor in parallel with a broken one renders them both useless right?

The broken one actually needs to be de-soldered?

[Mira Yurizaki]

17 minutes ago, kris2340k said:

I cannot confirm this, I have a multimeter? if its as simple as measuring resistance or something let me know

Capacitors can either fail to open or short circuit. However, I wouldn't really trust this 100% and if you can find something to measure capacitance that would be better.

17 minutes ago, kris2340k said:

My current fix idea is to solder a Can based capacitor replacement above the surface mount (which I think is dead)
Wiring them in parallel

This is not a good idea. Capacitor types behave differently and connecting capacitors in parallel adds to the capacitor already there. So if the suspected dead capacitor isn't really dead, just not operating to spec, that will also change the behavior of the circuit.

 

17 minutes ago, kris2340k said:

Now from what I understand, Wiring a good capacitor in parallel with a broken one renders them both useless right?

I don't think it would make the good one useless. Either one of three things will happen:

• If the bad capacitor failed to short circuit mode, then the new one won't be affected (electricity takes the path of least resistance, you can't beat short circuits)
• If the bad capacitor failed to open circuit mode, then the new one will be used.
• If the bad capacitor hasn't quite failed, then the capacitance of the new and old ones will combine, causing a possible issue if the circuit was designed with a specific capacitance in mind, plus a small amount of tolerance.

17 minutes ago, kris2340k said:

The broken one actually needs to be de-soldered?

Yes. You should remove dead components and replace them.

[Squish4058]

9 minutes ago, Mira Yurizaki said:

 

Yes. You should remove dead components and replace them.

Thanks
Its just a very fragile board and I wanted some way on confirming its this specific cap before I destroy a board
I might probe it with a voltmeter whilst its running (only a 12v board) and decide if its failing to short or open as its definatley still storing just not as well.

Thanks!

[Mira Yurizaki]

4 minutes ago, kris2340k said:

Thanks
Its just a very fragile board and I wanted some way on confirming its this specific cap before I destroy a board
I might probe it with a voltmeter whilst its running (only a 12v board) and decide if its failing to short or open as its definatley still storing just not as well.

Thanks!

This should help