The best would be to have a thermal imaging camera. Thia will show defective component as a hot spot. Overall the method is to power up the board from regulated power supply with control on max current. Question is whether you have such power supply available

I have a bench power supply. I haven't tried out if it automatically shuts down if a short is deteced by it though.
I don't have a thermal imaging camera.

Like @zami555 said, a thermal camera would make quick work of a short in the board... They are getting cheap these days and you might find a good deal somewhere. 😋 I have a "basic" one, but it's been extremely useful.

If you have a bench supply you can make do but it will take longer. A simple way would be to use either isopropyl alcohol (ISO) or canned air. Curious, how do you know it's a short? Is there continuity from 5V to ground?

The idea is to give the board very low current (assuming it's a short) on the 5V rail. I'd set the current limit to something small and this will depend on whether it's a trace short or a failed component that's shorting to ground. Maybe enough to get the spot warm but not hot! (<50-150ma) You can set a current limit but you can also just turn up the voltage until you hit about 100ma. If this is a true short to ground this will be only a few 100 millivolts.

Connect the bench supply to the 5V rail and ground to ground. With low current going to short, start wiping ISO around in small areas at a time and watch for a spot that evaporates faster. If you're passing enough current to heat up the spot but not burn things, you should eventually find a spot or part that's shorting to ground. Canned air also works in this manner. Spray small areas at a time and let frost over. Then apply the low current and watch for quick evaporation.

These aren't the best examples, but you can get the idea. Hope that helps. Update if you find the short!

https://youtu.be/aMoknD2cK98?si=ZggBAdfUwyL944Aj&t=14

https://youtu.be/HGaSVDi4pt4?si=UmY7faCaQCKcfMR8&t=26

https://youtu.be/cWQo-Fk4f24?si=_KHnerZmpFzwKtsj&t=37

I found out that the board doesn't actually have a short.
I measured 16 ohms between the 5V and GND power pins, which I (and my multimeter) thought are a short, but it turned out that that's normal.
The board is working fine.

naujoks wrote on 2024-06-23, 07:41:

I found out that the board doesn't actually have a short.
I measured 16 ohms between the 5V and GND power pins, which I (and my multimeter) thought are a short, but it turned out that that's normal.
The board is working fine.

👍 That's great! I was curious how you knew it was a short. Like, was the PSU shutting off rapidly or did you smell smoke... 😬 🤣 Glad it's all working.

I watched many Youtube videos of guys repairing old boards and before firing it up, they measure for shorts between the power pins. Every time when the MM was beeping they found a shorted cap.
All the boards I was working on never beeped, this board was the first one. I measured other boards for comparison, and they were all above 80 ohms, which wouldn't have set off my MM.
I now learned that 16 ohms can be normal.

Wait... So you removed a bunch of good parts by mistake? 😬 Oh well. Lesson learned.

Let's say I tested every tantal cap for functionality, mkay? 😀