FC not getting power from ESC?

[Gnarlock]

Hey there pilots!
Noob problem, but this is my 2nd attempt at building an acrobrat. First stack I tried was a Magnum mini w/out the vtx on stack. This time its a LUX micro f4 stack. I have had the same issue with both stacks, so I know it must be me that is the problem. After I get everything soldered up and connected, I plug into Betaflight and get the standard sets of beeps. I update FC firmware, test the motor directions, and all the other new board things. Then I go into BLHeli and it doesn't connect. I plug in a battery to the quad and only get the first set of beeps. No lights on the FC, VTX, or RX light up. Both times I have checked the physical connections between the boards, and it looked fine. I'm hoping I'm just doing some little thing wrong. Am I forgetting to bridge some jumpers? Or could it be the type of solder I'm using? Any help would be much appreciated!

 

[HighTechPauper]

Hi @Gnarlock, welcome!

With no USB and a battery you should definitely get all 5 tones, the first 3 are the ESC's booting up, the second set is the when the FC checks in (talks to) the ESC's. With no power indication on anything besides your ESC's it sounds like a wire harness between the ESC and FC is either missing or pinned out incorrectly. Normally in a stack the battery pigtail goes to the ESC, which either makes and feeds 5 volts to the FC, or passes battery voltage to the FC and it makes it's own 5 volts out of that battery voltage (all connected through that wire harness I was talking about, all FC logic needs 5 volts to run). Take a look at what you have and let us know what type of setup it is. I can look up the stack in the long run if needed, but it is a good idea for you to think about what you have and how it works.

 

[Gnarlock]

@HighTechPauper Thanks for the help and the warm welcome!
It's the Lumenier Micro Lux v3 stack. It has a stacking pin connector between the boards. I thought it might not be seated all the way, and tried out different spacers on the stack screws. It is seated flush for sure now, but still no power getting to the FC. I'm not sure if this information helps, but when I plug into Betaflight I get all 5 beeps. That means when the FC has power it can talk to the ESCs, right?

 

[coyote_dc5]

ESCs shouldn't beep at all in BF as this is usually just a 5v input into FC board. They should only power on with LIPO connected. Can you see spin motors from BF motors tab with LIPO connected?

 

[HighTechPauper]

@HighTechPauper Thanks for the help and the warm welcome!
It's the Lumenier Micro Lux v3 stack. It has a stacking pin connector between the boards. I thought it might not be seated all the way, and tried out different spacers on the stack screws. It is seated flush for sure now, but still no power getting to the FC. I'm not sure if this information helps, but when I plug into Betaflight I get all 5 beeps. That means when the FC has power it can talk to the ESCs, right?

It was late last night so I wasn't thinking as clearly, yes the FC and ESC are talking to each other since you tested the motors during config. Your issue is all about power to the FC, since it is a header pin connection we know the "harness" between the 2 boards should be good. It looks like you have a bad voltage regulator used to step down the battery voltage to run the 5v rail. You will need a voltmeter to try and prove that but there really isn't much that can be done but to replace the faulty board or add a separate VReg to the build. It does seem strange to have 2 different stacks with apparently the same issue (based on your description), and you shouldn't have had to bridge anything to get that voltage, that would usually only be done for a peripheral attached, like cam/vTX or RX may have choices between 3.3v, 5v (for RX) or 9v or 12v for cams and vTX's etc.

 

[okw]

You might try disconnecting everything from your FC (camera, VTX, receiver, etc). It's possible that something is shorted and pulling the 5V supply down to a level that the FC doesn't like. This would explain why you've seen issues with multiple FCs.

With only the FC and ESC connected, see if you get the correct beeps. If you do, start reconnecting things one at a time until it stops working. If you connect something and it stops working again, that last thing you connected is likely the problem. It may also help to use a voltmeter to check the 5V supply each time you connect something.

ETA: And don't forget to use a Smoke Stopper when connecting the battery until you get this figured out.

 

[Gnarlock]

ESCs shouldn't beep at all in BF as this is usually just a 5v input into FC board. They should only power on with LIPO connected. Can you see spin motors from BF motors tab with LIPO connected?

You are right. I meant to say connected in BF and LIPO when I was testing the motors.

 

[Gnarlock]

You might try disconnecting everything from your FC (camera, VTX, receiver, etc). It's possible that something is shorted and pulling the 5V supply down to a level that the FC doesn't like. This would explain why you've seen issues with multiple FCs.

With only the FC and ESC connected, see if you get the correct beeps. If you do, start reconnecting things one at a time until it stops working. If you connect something and it stops working again, that last thing you connected is likely the problem. It may also help to use a voltmeter to check the 5V supply each time you connect something.

ETA: And don't forget to use a Smoke Stopper when connecting the battery until you get this figured out.

I will try that. On the 2nd build I ran the Runcam Split straight off the battery lead, because I was thinking it was drawing power away from the FC. So now it's just the VTX and RX

 

[Gnarlock]

It was late last night so I wasn't thinking as clearly, yes the FC and ESC are talking to each other since you tested the motors during config. Your issue is all about power to the FC, since it is a header pin connection we know the "harness" between the 2 boards should be good. It looks like you have a bad voltage regulator used to step down the battery voltage to run the 5v rail. You will need a voltmeter to try and prove that but there really isn't much that can be done but to replace the faulty board or add a separate VReg to the build. It does seem strange to have 2 different stacks with apparently the same issue (based on your description), and you shouldn't have had to bridge anything to get that voltage, that would usually only be done for a peripheral attached, like cam/vTX or RX may have choices between 3.3v, 5v (for RX) or 9v or 12v for cams and vTX's etc.

I have a multimeter that I will use to check once I get home. I ran the Runcam Split off the battery lead to see if that helps (thinking it was drawing too much power). So now it's just a VTX and RX running off of the FC. It is weird that two stacks both had the same problem. I thought for sure it was something I was doing lol. I'll update after I test the board

 

[Gnarlock]

You might try disconnecting everything from your FC (camera, VTX, receiver, etc). It's possible that something is shorted and pulling the 5V supply down to a level that the FC doesn't like. This would explain why you've seen issues with multiple FCs.

With only the FC and ESC connected, see if you get the correct beeps. If you do, start reconnecting things one at a time until it stops working. If you connect something and it stops working again, that last thing you connected is likely the problem. It may also help to use a voltmeter to check the 5V supply each time you connect something.

ETA: And don't forget to use a Smoke Stopper when connecting the battery until you get this figured out.

Luckily I got my Viply smoke stopper in the mail the other day!