Major(?) electronics issue with MambaX/Holmes PP2700kv/SHV500V2 on 4S - shorting out?

[jessedacri]

Alright, bear with me here, have an electrical gremlin that I'm hoping is not something expensive or is simply a defect - I recently bought the following brand new:

Mamba X
Holmes Hobbies Puller Pro 2700kV standard
Holmes SHV500V2 servo
Spektrum DX5C with SRS6000 receiver

Built a 10.2 raw builder's kit and fit everything to it and all has been well for about 3-4 packs. I've been running mostly 4S on 5-year-old 3300 packs which have already netted me hours of very, very slow crawling and some high speed trails.

Anyways, since I haven't finished my hilux body yet I found a way to fit my "clean" TRX4 bronco body on, stuck my "beater" bronco body on the TRX and went out with a friend to Vasquez Rocks on Saturday. I plugged the PowershiftRC LEDs into a traxxas JST splitter. Had a blast for 2+ hours and then the truck froze up completely and the Mamba rebooted. I pulled the body and checked connections, all was well and the truck was responding again. I gave it some throttle and it immediately rebooted again. Figured it was the old battery or a dying cell so I swapped another also old (but balanced and all cells at 4.20) 4S pack in, plugged it all up and ran again. 5 minutes later the truck rebooted again, and then shortly went into a full on flicker-fest. The LEDs flickered on and off and the Mamba was constantly boot-looping. Now I know my batteries are old but two different packs shouldn't do this. I managed to capture a quick video of it doing this before I unplugged everything and went home. Here's that video video of the truck frozen with the lights flickering:
https://www.youtube.com/watch?v=B5TN...ature=youtu.be One of the LEDs popped out in my haste to get the body off the first time the glitch happened. Should be unrelated.

Things I noticed so far:

- The reboot seemed to happen mostly when the steering servo is in motion, especially at full lock. The endpoints are set and it's not stressing hard against anything at either side of full lock. I'm using the outer hole on the Vanquish clamping horn. Not positive this was the culprit, just something I noticed.

- When I fiddle with the Mamba X ON/OFF switch, sometimes when turning it off the steering servo violently whips well past full-lock to the right, going wellllll past the limits of the link and steering assembly. When I turn it on again, it ends up resetting during the boot up process and is fine. I honestly wish the ON/OFF didn't exist.

- Powershift LEDs look to be rated up to 3S. Possible something got too hot here on 4S? They didn't seem warm during the drive and it was under 60F and cloudy with a drizzle. Still not sure if this is what could have caused symptoms like this.

- the problem persists with the LEDS not plugged in, and the JST splitter not in the picture either

- No binding in the drivetrain, Motor, Mamba X and SHV500 V2 were all lukewarm to the touch.

- The truck tipped over into a shallow creek once on a trail the day prior, with no body. Nothing got submerged, but everything did get splashed. Every component I bought is either water resistant or waterproof, so shouldn't be an issue? I grabbed it within two seconds of it happening. I'm not submarine commanding this thing, especially in its unfinished state. The truck has gotten a cleaning with WD-40 and a shop air compressor after every run.

- I'm running a TRX plug on the Mamba X with a pigtail JST accessory connector. Did this because I have a mix of TRX, XT60, and Deans packs and all my adapters go to TRX, so figured it was the most common one for now. Could it be a messy solder point causing this? I'm going over all that today to make sure, but the JST+Mamba X leads together were tough to fit into the TRX connector cleanly.

Any ideas here on where to start or has anyone had a similar issue in the past? I haven't had time to do a full inspection but will be later today once I get through some work. I plan on running a brand new 3S pack around the yard to rule out the old 4S packs.







And before all the drama we had a ton of fun with dueling TRX-4/SCX10.2 Broncos!

[Voodoobrew]

Did you try with steering servo unplugged, sitting in dentist chair so read really quickly.

[Voodoobrew]

The servo swing is an issue on battery powered servos, opposed to esc powered, happens when esc/rx is off but servo still has power.

[robert@castle]

Originally Posted by jessedacri

- When I fiddle with the Mamba X ON/OFF switch, sometimes when turning it off the steering servo violently whips well past full-lock to the right, going wellllll past the limits of the link and steering assembly. When I turn it on again, it ends up resetting during the boot up process and is fine. I honestly wish the ON/OFF didn't exist.

From the servo's page on Holmes' website.

If using an ESC with a power switch, the battery must be disconnected from the ESC and servo when not in use to prevent damage to the servo and/or battery.

I would say you should never use the switch on the ESC because it seems like the servo doesn't like it when the receiver turns off. You can cut the switch off and solder the two wires together to keep the ESC always on.

As far as the reboots: Check all solder joints and make sure nothing is loose. Constant reboots sounds like a loose power wire somewhere, maybe a bad connection in the battery plug. Wiggle each wires while holding the plug and see if it ever reboots. I'm betting one of the contacts in the ESC side of the plug is loose and losing connection.

The LED's or servo shouldn't be able to pull the battery voltage down enough to cause the ESC to reboot.

And before all the drama we had a ton of fun with dueling TRX-4/SCX10.2 Broncos!
Image
Image

Good look truck.

[jessedacri]

Originally Posted by Voodoobrew

The servo swing is an issue on battery powered servos, opposed to esc powered, happens when esc/rx is off but servo still has power.

Originally Posted by robert@castle

From the servo's page on Holmes' website.


I would say you should never use the switch on the ESC because it seems like the servo doesn't like it when the receiver turns off. You can cut the switch off and solder the two wires together to keep the ESC always on.

As far as the reboots: Check all solder joints and make sure nothing is loose. Constant reboots sounds like a loose power wire somewhere, maybe a bad connection in the battery plug. Wiggle each wires while holding the plug and see if it ever reboots. I'm betting one of the contacts in the ESC side of the plug is loose and losing connection.

The LED's or servo shouldn't be able to pull the battery voltage down enough to cause the ESC to reboot.


Good look truck.

Thanks for the info! Sat down with the truck and went over everything carefully. I am almost completely sure it's my connector - it's a generic TRX one that seems to be made of flimsy plastic. Got it to reboot a couple times with a few firm wiggles, so I resoldered it and slid some electric tape under the contact (where it seats in the plastic bed of the male prongs) to hopefully make things a bit tighter for now. It's holding now.

On that note, I think I'm going to move this build off of TRX connectors and go with something larger and better built. Are y'all using XT-90s these days? I find it awfully hard to make a compact solder job with the JST pigtail and the the thick power wires coming off the Mamba. The XT-90 looks nice and easy with the "cup" that the wire sits in. Feels like I could jam both my pigtail lead and the larger awg cable in and keep things tidy for the solder.


Glad this is a minor issue! I'm going to delete the on/off switch as well while I'm at it. Thanks all.

[DRTMI]

Originally Posted by jessedacri

On that note, I think I'm going to move this build off of TRX connectors and go with something larger and better built. Are y'all using XT-90s these days? I find it awfully hard to make a compact solder job with the JST pigtail and the the thick power wires coming off the Mamba. The XT-90 looks nice and easy with the "cup" that the wire sits in. Feels like I could jam both my pigtail lead and the larger awg cable in and keep things tidy for the solder.


Glad this is a minor issue! I'm going to delete the on/off switch as well while I'm at it. Thanks all.

XT90's are too big. XT60's will be fine, and before you say those are too small to solder the X wires and the JST pigtail into, I am running XT30's on my X. The trick is to solder the JST wire in first and follow it up with the ESC wires.

[Voodoobrew]

If I had to pick a new plug for all my systems it would be XT60, currently using the older deans without much problems but I started using adapters to XT60 instead of changing plugs where it's convenient.

[KV242]

I used to use trx, ec3, xt60 and xt90 depending upon model, but I got tired of endless adapter cables and different charge leads. Got to be a real pain in the a$$! So I went with my most demanding model (6s power boat) which had the xt90's, and went with xt90's on everything across the board. I now have sufficient current capacity on every battery and esc connection. Gone are the many adapter cables (which will add resistance) and I only use one type of charge lead now. Life is much simplified, and I can now use any battery on any model quickly and easily. And as a bonus the xt90s are easier to handle with larger hands, and easy to solder too.

[HumboldtEF]

Yeah I'd say theres nothing wrong with using an XT90 if thats what you want to use, its bigger than needed for a crawler but theres nothing wrong with that. I do use XT60's and adding in some wires for a JST lead is do-able but it is a little bit tighter, I find all it requires is a slightly larger diameter heat shrink than usual. I'll usually solder the battery wire first and then add the smaller JST leads on top of that, just make sure you get a good solder joint and wait for the whole solder joint to flow as its easy to cold solder the smaller wires.

[sappy96]

Is the AVC on? That will crank servos and the strain might be too much.

As far as xt60 cs xt90. I ran 90s but swapped to 60s to save space in some of the tighter rigs.

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