Hi guys,
3DR arducopter, APM2.5 :
during ESC calibration i noticed one of the fourth ESC (motor4) an extreme overheating. Three possibilities : ESC problem, motor problem or PDB problem on output motor 4.
I excluded ESC and motor problem by swapping the "hot" ESC by a nother ESC : this other ESC was also getting hot. Then I used PDB output n°3 on motor 4 and everyhting was fine -> this excluldes a short on motor n°4.
So obviously I have a problem with my PDB on output 4, that provokes extreme overheating of the ESC. I measured with an ohmeter the resistor between the + and - of PDB output 4. It is the same as all other outputs (so no short at that level). Plus the fact that even if the ESC overheats, the motor 4 still turns fine !
So what could be a cause on that PDB that makes the output 4 , thus the ESC4 overheat, but still driving the motor to turn fine ??? A short on the PDB ? Did I solder something wrong on the PDB ?
Please help because I have exhausted all I could test. Should I disassemble the whole thing to get a closer look at the PDB ? What other tests could I do on the PDB to detect an eventual issue ?
I want to avoid having to replace a PDB, not only is it more dollars to dish out, but further it is a pain to assemble and solder.
Thx,
Hugues
Replies
Hi.
I'm using an external BEC (non-lineal) with my octo. I think it is a must.
http://www.hobbyking.com/hobbyking/store/__767__766__UBEC_Regulator...
I disassembled the 3DR quadcopter to unmount the PDB. I then checked every single solder, they were fine. I checked if there were shorts but all was ok. I checked to be sure no bare cables or connectors were touching conductive parts of the PDB or connectors, all was ok.
I did the test described in my last post, the ESC number 4 was still overheating.
I then noticed that the 3DR PDB board has a specificity for its output number 4: this is also the output of the PDB where a black & red 5V servo cable is soldered to feed the APM output rail.
I then disconnected this cable from the APM and BINGO, problem is solved !
Conclusion and summary: for all of you out there who use a 3DR power board and 3DR power module, you must DISCONNECT the red&black servo cable between the PDB and the APM2.5 output rail.
If a moderator of the arducopter wiki manual reads this,could you please add this instruction to the 3DR assembly guide ?
thx,
Hugues
However i want to pinpoint the root cause(s) of this PDB output 4 causing ESC overheat.
I will disassemble the quad to recheck evey solder, to recheck there are no shorts. I will also try this test: i will power ESC 4 by PDB output 4, but using the signal wire of PDB output 3. This test will tell me if the problem is on the power/Dean circuit side or rather on the motor signal drive circuit.
Will keep you posted