Electrical gremlins, need help!

[cjthing]

Hopefully someone with some more experience can provide some insight because I'm stumped. At a local comp a couple nights ago the XR10 started "stalling" and not functioning properly. The steering will momentarily stop working, the rear motor will "jump", but within a couple seconds it will go back to normal, then repeat.

I have noticed that when the stalling happens the RX light goes red, obviously not normal.

So far I have tried three different receivers, replaced TX batteries, tried a different TX, checked voltage with Castle Link, and last night shortened all the wiring and resoldered the deans plug on the ESC side of the battery. Yes my power wires from the esc's are taped off going into the receiver.

specs...
stock chassis
Hitec 7980
HH Crawlmaster Motors
HH BRXL x 2
Castle BEC

I have a feeling I need a new BEC or another Hitec servo needs to be sent in for repair.

Thanks for any insight

[OFFROADRCKOREA]

Whats your BEC voltage set too? Sounds like the Servos pulling more power than available.

LIK

[cjthing]

BEC is set at 7V, never had a problem over the past couple months until two nights ago.

[T3rry]

Sounds like whatever is powering your rx us starving it... how is your bec wired?

[OFFROADRCKOREA]

Do you have another BEC to try? If so id recommend doing that. How your servo working? Some times they start to bind and can cause issues like this as well, but ive never seen the hopping haha.

LIK

[Krawler Kev]

Check the signal wire on the BEC. I had the same thing happen to me and thats what it was.

[cjthing]

All of my wiring is done just as Harley shows in his electronics guide for the 4PL, battery to BEC to receiver, red wires are pulled from ESC's to receiver.

I am probably going to pick up another BEC and try that, having a spare wouldn't hurt. I have heard of people using micro deans so they can be swapped easier, is this an OK idea? I don't see it hurting anything.

Servo does seem to get warm, not sure if its too warm though. Probably pick up a spare as well as I hate being down.

My main question is that the light on the receiver goes red when it "stalls", when I searched I saw someone ask if this was the case but never heard what it means.

At this point, with all the spares we collect its no wonder people end up with 2 or 3 XR's after a couple years

[Robbob]

What kind of Radio?

Guys at my lhs running Spektrum radios have to run a capacitor plugged into the RX most of the time. If they dont they same exact thing happens, you brown the rx and it drops.

[ROWDY RACING]

This may help?

Receiver bypass adapter

[cjthing]

Using a Futaba 4PL, tried 3 receivers and another 4PL as well, all without any change.

Rowdy thanks for the tip, since I am a newb this changes the BEC to power the servo only correct? From what I understand the receiver that came with the 4PL can handle the power the BEC puts into it.

I have had several people who I consider experts look at my set-up, tried a y-harness etc and everyone is stumped.

I hate the buy and replace parts until the problem is gone but that looks like the road I am going down.

[ROWDY RACING]

1 esc will power the rx with the adapter.

The bypass adapter is $5 plus shipping, could be a cheap fix?

[treys1]

Originally Posted by ROWDY RACING

This may help?

Receiver bypass adapter

Use the receiver bypass to power the servo, and put the red wire back in one of the ESC plugs so it can power the receiver. That way the servo drawing on the BEC will not brown out the receiver.

With two BRXL's there you have 10amps worth of 6v not being used that could power the receiver..

[cjthing]

I am open to anything to get this thing working again, and maybe even working better. Is the bypass adapter Rowdy shows function the same as a y-harness? I understand the packaging benefit for sure.

I have tried a y-harness and it made no change, and since the truck worked for two months I wonder what changed....

thanks for all the help guys, it is greatly appreciated!

[T3rry]

Originally Posted by cjthing

I am open to anything to get this thing working again, and maybe even working better. Is the bypass adapter Rowdy shows function the same as a y-harness? I understand the packaging benefit for sure.

I have tried a y-harness and it made no change, and since the truck worked for two months I wonder what changed....

thanks for all the help guys, it is greatly appreciated!

it's the same as a Y just with a wire removed...

if you have a Y you can modify it like this

[cjthing]

Just looked at the XR again and it definitely seems to be steering related, with the servo disconnected from the rx the motors function fine, no glitching.

So I am thinking I need a new servo, but could it still be the BEC?

[treys1]

Originally Posted by cjthing

Just looked at the XR again and it definitely seems to be steering related, with the servo disconnected from the rx the motors function fine, no glitching.

So I am thinking I need a new servo, but could it still be the BEC?

It could be brownout with the servo pulling power, which that modded Y Harness or the RX bypass plug + powering the RX off one of your BRXL's would fix.

Before you worry about spending $ on a new BEC or even servo I would suggest spending the $ on the RX bypass. I have bought several of those from Chris_The_Battery_Man and they go into anything I build for me OR my friends!

[TSK]

Definitely pick up a bypass adapter and run one red from a esc.

Also, check for binding in your steering linkage, and make sure your epas are set properly. I know some times it's easy to inadvertently hit a trim switch and add epa to your steering. That will cause the servo to draw high amps as it tries to push the steering past it's physical limits rsulting in the brown out to the rx.

[cjthing]

Thanks again guys, I will try the wiring changes tonight. I have a y-harness I can modify so if that works then I will order up the bypass adapter as its a lot cleaner. Will also check the epa's as well.

If nothing else I better understand the electronics side of the XR and was able to clean up a lot of wiring in the process.

[treys1]

One thing I would recommend if making your own bypass. That picture shows only the signal going to the RX, I would run signal and ground to the RX.

[TSK]

Originally Posted by treys1

One thing I would recommend if making your own bypass. That picture shows only the signal going to the RX, I would run signal and ground to the RX.

+1