Ok, so here's how it started...

The JST connector got stretched and finally the neg lead broke off, so I took the old connector off, and not having a replacement, direct wired the leads to the battery pack. not a problem, except for a split second, I had them reversed, and smoked the MOSFET controller. Not a problem... I went to www.digikey.com bought 3 mosfet controllers and replaced it, the other 2 chips I got to repair another fried 4N1 on another BCX, and the other chip as a spare. So, I replaced the MOSFET on the one BCX, and everything works fine.

Now, the one BCX 4N1 that I reversed the leads on...

I replaced the MOSFET that got smoked, and the motors work fine. While I was in there, I put a brand new longer plug for the battery in, soldered tot he board. Took teh old one out, soldered in a new one from hobbico. Motors work fine, but when I plug in the servos the green LED dims, and if I move the cyclic controls, the LED dims more, nothing happens with the servos, and it slows the motors down.

Why? What else coudl I have fried in there, that would cause this.

I want to add, that when in there, I noted that some of the components differed from the first 4N1 that I worked on. some of the components are in different locations, and the antenna is routed differently through the board.

I didn't see any other components that were visably toasty or discolored.
Anyone hazzard a guess as to the problem?

Thanks,
John

You could try checking whether there is a prob with your servos. I had that problem and tried 3 diff 4-in-1's and they all gave the same prob. I have the problem just on one servo so I assume there is a problem with the servo. You may need to repair or replace them.

Did the light dim on the 4N1 when you gave cyclic input to the servos?

I have the problem whittled down.

If I plug in a receiver battery into one of the servo slots, the other servo will work. This means I fried the component that limits the voltage for the servos, from 7.4 volts to whatever is safe for the servos. looking at the circuit board, the trace from the positive battery wire to the positive servo wire is almost a straight shot. There is only one component in line, in the trace. if I jumper over this component, the servos work but with too much voltage. so... I just have to identify this component and replace it. This is a pain. anyone know what component this is? no markings on it, just a brown box, face mounted...