The circuit board where the wires enter looks like at least a dual layer board. And, the traces are kinda big and act as a heatsink when you are trying to solder. You have to be careful not to put heat on the solder joint for too long or the heat will travel along the traces and heat up whatever is nearby possibly damaging it. It's better to use a hotter iron for a few seconds than to hold a cooler iron on there longer.
Negatory - I have a big hot tip on it and have no problems soldering most things. I have never ran across solder such as this is all I am saying - it was a bio*tch lol
Ok its doing the same thing with the MM ESC - I did find a back connector on one of the motor wires so I am going to redo the connectors and try again.
Is there a way to replace the motor wires oneself?
I haven't taken apart the Mamba Max motors, but in the manual it says you can cut as much as you want (within reason). They must attach wires to the coil ends within the motor. I, and others, have tried taking off the end bell and couldn't undo one or more screws.
Well, you can't cut much wire off those. When they made the motor, they wound the coils, and brought the ends out to attach connectors to. They had to scrape the insulating varnish off the individual conductors so the solder would stick. If you cut the wires, you'll have to do the same thing. It's not fun. If anything, you could replace the connector. Just heat up the solder joint and slide it off.
Ok, update. I re-soldered the connector onto the wire after cleaning it and the wire end. Got it all hooked up and it runs perfect! I will try the 9920 again as I suspect the motor wire was the culprit on it as well.