Short circuit location with current

[fretless]

Hey guys,

I have a phone that has its Vbattery rail shorted somewhere. I was thinking if it is safe to try and locate the short using 1A, maybe 2A of current. The short measures 0.3 ohms.

[Rerouter]

and blow it up in the process with a 1.3W short on the 2A current, aim for 500mA, this gives you 150mV to trace it out with, while being a much smaller wattage

[SeanB]

Try 0.5A first, and limit the voltage to 3v so that if the failed capacitor ( most likely suspect) blows open you do not fry the whole board. Feel for something warm, or use a thermal imager if you have, or an IR thermometer.

[fretless]

I'v read somewhere that you can spray the entire board with freezer spray and the damaged component/trace will become apparent. However I'm worried that it may cause some damage because of thermal stress. Am I wrong?

[zapta]

A thermal camera may help.

[nctnico]

I usually set a PSU to 1V (or less) and push current into a circuit. The short is easy to find with a multimeter. The short has the least voltage across it.

[fretless]

If I were to spray parts of the board with freezer spray and then look for parts that defrost first to find the short, would 0,5 A be enough ( the short is 0.25 - 0.3 ohms) to spot the difference?

[Ghydda]

If I were to spray parts of the board with freezer spray and then look for parts that defrost first to find the short, would 0,5 A be enough ( the short is 0.25 - 0.3 ohms) to spot the difference?

A short answer: maybe, it pretty much depends on how uneven the thermal mass of the populated board is. If is very uniform chances are good. If no, then things will defrost very unevenly regardless of you feeding in a quarter of a watt or not.
But why not just try it anyways? Couldn't hurt.