Isolating an issue to TX or RX?
 

Greets! I recently swapped a bunch of gear around between my two cars and revealed what I think is a receiver issue but would like to be sure before I replace it.

The issue is with my kid's brushless Rustler. This car worked fine with my Flysky TX/RX but when I installed his AE XP3D (w/Spektrum module) and Spectrum SR3000 it glitches badly on hard acceleration from stop. It'll launch then die, no servo control or anything, and then launch again, then die.

I did recalibrate the ESC to the AE/Spektrum radio and verified that all batteries were adequately charged.

Last night I briefly swapped in an old Traxxas AM setup I had and the issue was resolved, so it's definitely an RX/TX issue IMO.

I don't have a spare Spektrum RX or TX to swap out; can anyone suggest a crafty way to determine where the issue lies? I'll buy a new receiver if that's the issue but I don't want to spring for that and discover that it isn't...

TIA!

Do you have a LHS that might let you "test" a different receiver? Is this the first time you've had this system in this car? Spektrum's receivers are known to sometimes brown-out and thus require a power cap/bec to work properly.

However, simply playing the odds, unless the Tx has been dropped, I'd assign about a 99.8% chance it is the receiver.

Thanks for that. My LHS is pretty good and they carry Spektrum but I'm new to the hobby and didn't know if it would be improper to ask to use a NIB receiver for test purposes.

This is the first time in this car, but the Slash has a setup that's really similar (same battery and ESC, different motor) and it never had an issue there so I wonder if I juked the RX when I moved it over... Took it apart and didn't see anything amiss, but those electrons are little.

Depends on the shop. Some will without hesitation, some might look at you like you're insane but it never hurts to ask.

I did some more testing....

1. No glitching with Traxxas AM setup.

2. No glitching with FlySky.

3. Glitching still present with AE/Spektrum setup but only on full-throttle launches. If I use my kid's profile (Throttle EPA about 25%) no issues.

4. During the glitch the green LED on the RX goes out, which could either mean a loss of power or a loss of connection to the TX.

5. While experimenting I tried multiple wire layouts, putting the RX as far forward (and away from the ESC) as possible; no change.

Any more input?

Band-aid or corrective surgery, you pick.

As mark said, this is a know issue with Spektrum and either of the two linked above should fix it, although, I'd highly suggest the BEC since it's programmable and will allow you to run HV servos, if you so choose. ;)

Brownout.... that fits the facts, actually. In the old install the car was running a brushed Reedy motor. The new install is brushless with some punch; quite probably it does draw way more juice on launch.

Being cheap I'll probably just get some servo extensions and add a cap myself. Thanks loads!

A 4700uF cap from Radio Shack wired to a servo extension solved my problem. Thanks for the help!