Hi, some electrical engineer here? 
I have here HGLRC Zeus 10 AIO and once when I throttled up to take off, the quad just jump and fall dead silent. After some investigation, I found that the ESC works and beeps up when the battery is connected but nothing else powers up. Also when 5V over USB is plugged in, CPU and peripheries plugged on USB powered pads are working, with USB plugged in I was able to "take off" so the problem looks like only the 5V conversion. After stripping out the FC and some measuring, I found the nonworking 5V pads are shorted to the ground, so I would guess the 5V DC/DC converter burned off, I also tried to unsolder some components but no luck to remove the short, so I am not aware of what else could cause it.

  

I can also send detailed images with markings if needed.
Thanks for your ideas.

Burning out your 5v regulator wouldn’t typically result in a short between 5v and ground, but you definitely have an issue somewhere on your 5v rail.

It looks like you have something going on in the area of the board below, specifically the 6 pin IC and the capacitor next to it, possibly also whatever component is near the top to the right of the inductor (to the right and slightly above the inductor marked “6R8”):


But, I can’t see clearly enough from your photos.
If you can post clear up close photos of that section (please make sure top markings of things are legible), maybe we can get a better idea.

Hi, here is a link to album with detailed photos https://photos.app.goo.gl/oqiTktfbBPKtf9wX7.
Yesterday I've already tried unsolder the GbEAA and DE=A1D, which did not help.

I’d suggest starting with cleaning all of your pads with solder wick. Your photos show a ground pad potentially shorting to the cam pad, so I’m guessing perhaps other pads may have similar issues. Make sure you clean up the edges of the pads as well on any that wrap over/around the board.

After that, give it a good a scrub down with an old toothbrush and 91% or 99% isopropyl alcohol.

Check to see if there is still a short between a 5v pad and ground afterwards. If so, post close of pictures of both sides of the board as well as the edges.

(10-Aug-2023, 12:51 AM)Gify25 Wrote: Also when 5V over USB is plugged in, CPU and peripheries plugged on USB powered pads are working, with USB plugged in I was able to "take off" so the problem looks like only the 5V conversion. After stripping out the FC and some measuring, I found the nonworking 5V pads are shorted to the ground

The first sentence tells me the 5V bus is not shorted to ground, otherwise the USB supply would not work. Are you sure the shorts you found were not caused by stripping out the FC for testing? I'd do as Lemony mentioned and clean up all the pads to be sure.

Based on your initial observation, that it flew with USB, and 4in1 beeps with lipo... the 5V buck circuit is likely at fault. So I'd also be looking at replacing the switcher IC after looking over the rest of the circuit for soldering issues. That tantalium cap looks burned a bit... could be bad. Based on size and location, I might guess that cap is used for the 5V switcher. From your second round of good photos, I can clearly see a large trace running between the inductor and the GbEAA chip. This means that chip could be the 5V buck IC that needs to be replaced... if it's not just that cap. OTOH, that other IC with the SM mark on it could be a buck IC as well (just don't see a low R trace to inductor myself, but modern switchers often come in qfn packs like that).

So all pads reflowed and cleaned, no obvious shorts founded. Added new photos there.

(11-Aug-2023, 05:37 PM)truglodite Wrote: The first sentence tells me the 5V bus is not shorted to ground, otherwise the USB supply would not work. Are you sure the shorts you found were not caused by stripping out the FC for testing? I'd do as Lemony mentioned and clean up all the pads to be sure.

Based on your initial observation, that it flew with USB, and 4in1 beeps with lipo... the 5V buck circuit is likely at fault. So I'd also be looking at replacing the switcher IC after looking over the rest of the circuit for soldering issues. That tantalium cap looks burned a bit... could be bad. Based on size and location, I might guess that cap is used for the 5V switcher. From your second round of good photos, I can clearly see a large trace running between the inductor and the GbEAA chip. This means that chip could be the 5V buck IC that needs to be replaced... if it's not just that cap. OTOH, that other IC with the SM mark on it could be a buck IC as well (just don't see a low R trace to inductor myself, but modern switchers often come in qfn packs like that).

There is one pad that is powered of USB, that one is OK (in official wiring diagram is used for powering receiver and LED strip), other three are shorted and never were USB powered. Unfortunately, I measured the short even before and hoped the striping would reveal some faulty wiring but no luck.
The tantalum capacitor didn't look burned originally, but as I was desoldering parts by hot air around it got browned so I hope it isn't damaged by it if it wasn't. Btw I tried to remove these 5 parts, but no one of them removed the short.

Also, I have the controller twice and the 2nd has 5v working, so yes the GbEAA is giving 5V (on the bottom left, probably 6th pin) and that is going to the 6R8, which on the shorted one did not, but removing the 6R8 cause to increase to 2V, then I swapped the GbEAA on the 2nd one and 5V is working fine so that one is probably fine. Tomorrow I will look at the SN 1CM I think you meant.

If the short wasn’t eliminated by removing any of those components, then you know your short is somewhere past them.

You’re likely looking at a shorted capacitor. On your board that is working, follow your 5v rail from the inductor (the component marked 6R8). On the board with the short, remove any capacitors along that trace one at a time- remove it, test for a short, if the short is still there, replace it and move on.

Is anything getting hot when it’s powered up?

(14-Aug-2023, 02:31 AM)Lemonyleprosy Wrote: If the short wasn’t eliminated by removing any of those components, then you know your short is somewhere past them.

You’re likely looking at a shorted capacitor. On your board that is working, follow your 5v rail from the inductor (the component marked 6R8). On the board with the short, remove any capacitors along that trace one at a time- remove it, test for a short, if the short is still there, replace it and move on.

Is anything getting hot when it’s powered up?

Mostly the 6R8 get hot for touch wery quickly, on a board both it's pins had continuity to ground now when I have it off, only the other of the connection to GbEAA pin do, so that would support what you said, I will look at that.

Perhaps a good sign the inductor is heating... perhaps the buck regulator is working and delivering current, but it's near 0V due to short somewhere. I'm with Lemony on finishing up the search for that short first. Caps are pretty easy to pop on and off to check. Tantalium caps do tend to short when they fail... and it's brown so that's at least one good target:

https://iopscience.iop.org/article/10.11...777/abf728

Nice, foud him, seems it was this capacitor. Without it no short, replace it, and looks everything is working. Will see how long it last. Thanks for advice where to look.

Excellent! Congratulations on finding the issue.