[Dave Holmes]

I'm still messing with my PBY Catalina that had me buffaloed in an earlier thread. (https://www.rccanada.ca/rccforum/showthread.php?t=137969).

This time, I got to fooling with it on a test stand and the starboard motor was acting really strange. Sometimes it would act like it wanted to start backwards, but most of the time it would kick in properly. However, when I throttled up it would wind up to about 2/3 and then just spin down and stop. At this point the ESC would often go through its beep sequence indicating it was booting up.

I had myself convinced the ESC had gone sour, but to be certain, I swapped the two ESCs; left to right and right to left. Same thing with the 'good' ESC.

OK, it must be the motor, but what the heck, let's go all the way. I pulled the starboard prop, cowling, etc to get at the motor and plugged the ESC directly into the motor, bypassing the extension wires provided by Great Planes.

Voila! Works perfectly!

How can the wires go bad? If they were shorting I would have smoked the ESC for sure, but it was OK. Out with my V.O.M. and sure enough, two of the wires register .4 Ohms resistance. The third was variable but the lowest I got was 54 Ohms. Checking found the female end (at the motor) had a bad solder joint and it had corroded and arced badly. Replaced the connector, put fresh heat shrink on it and now both motors wind up together like they did last year.

The symptoms were really confusing on the surface, but once I kicked into proper troubleshooting mode it was simple enough, and the repair was easy.

[CdnFlyer]

Way to go

[Cougar429]

Glad you finally found it. I've found many bad solder joints at the ESC/motor connectors and simply resolder them at the beginning just to be sure.