simplechamp

iTrader: (73)

Today I had one of my SR300 open because I wanted to add an antenna tube mount directly to the case. While it was open I noticed on one side of the circuit board there was quite a bit of room open. I, like many others, have found the internal BEC on the MMP can struggle with high torque, amp hungry servos, causing glitching and brown outs at the RX. Usually a cap is enough to fix the problem, and up until now I had always just used an external cap. But I figured if there is room in the RX case, why not put it inside?

I looked in my box of electronic components and found a 1500uF, 10V cap that fit perfectly. From there it was just a little CA glue to attach the cap to the board, and soldering up some spare servo wire to make the connections. Note that you can solder to any of the + pins and any of - pins. Also, it's hard to see, but there is a little slot on the side of the board next to the cap that the wires fit through perfectly (not sure if other Spektrum boards like SR3000, SR3100 have that too?)

Closed the case back up, everything fit snugly, and now I don't have to use up a port with an external cap. Still works just like when I had the external cap, no glitching or brown-outs.

EDIT: Someone pointed out to me that Novak has a warning about using CA glue on electronics. I only used 2 drops, so it should be fine, but if you decide to do this maybe use a dab of Shoe Goo or other adhesive.

Mr. Revo

iTrader: (1)

nice job, way to think outside the box. Also would save space inside the reciever box.

simplechamp

iTrader: (73)

Simple and effective, the best type of mod. Spektrum should make them like this from the factory, given how much current today's servos draw. They did put one cap on the board across the + and - pins, but it's only 100uF. Probably more for noise reduction than stabilizing voltage.

Derry

iTrader: (27)

Yes very cool mod! Thanks for sharing...With pics to!

simplechamp

iTrader: (73)

Here's the finished SR300. You can see the cap in the lower left corner. I also added the antenna tube holder, and swapped the green LED to a red one, since the car it's going in has red accents and hardware.

snoopyrc

iTrader: (2)

This is a work of art. Thanks for posting.

Speedytech7

That is a great mod, I think I might do this with my Futaba reciever. I haven't decided if my glitches are worth $5 though. We'll see.

1101

the RX's are good down to around 3v ish ?? so more likely The glitch buster cap also works by reducing noise,
Thats what it was doing for mine anyway
I checked what was happening with a scope, nasty brand servo putting lots of hash/noise into the rx, making it restart.

Artikbot

Off to mod mine...


Great job


Edit: Just finished, I didn't have any 1500 10V, so I ended up using three 470 25V (they also fit, but take up a lot more of space). Tested it, and works like a charm!! Did very fast 120º sweeps, like 50, and it had absolutely zero brownouts/restarts.

Btw, newer SR300 (RevA 2008) don't have that PCB gap, so you have to slot either the case or the board. I slotted the case with the solder, so the wires could go down to the traces.

twoheadsbrewing

I've been having the same issue with the SR300, and even the Spektrum glitch buster cap did not solve the problem. Does anyone know what the SR300 draws in terms of power and amps?

ozzy-crawl

iTrader: (14)

technically its not the rx that's the problem as it uses very little power, its the bec from the esc not supplying enough power for over amp hungry servos.

whats your setup ?

twoheadsbrewing

The guys at the Amain shop were telling me that it's very common for people to have brownout issues right after switching to a Spektrum system. Not sure if this is true, but prior to switching from the stock AM setup I had no problems.

HPI Blitz
Spektrum DX3E w/ SR300 Rx
Spektrum Digital S200 servo
Hobbywing 60A ESC (6v/1.5A BEC)
Tacon 3650 3200kv brushless

ozzy-crawl

iTrader: (14)

yes it is a common problem, the spekky rx is not as forgiving of low voltage as some.but 1.5a bec is fairly inadequate these days.
see on another thread your going to use a ubec,that should fix it.

simplechamp. great idea. iam just doing a 1/10 buggy that has no room for a cap yet alone a ubec,i think you just solved my problem

GLwagon

iTrader: (22)

Honestly, with todays high draw servos, average output from ESC's...
I run 4700uF minimum, & usually 9400uF of cap.

When at the track I keep a couple on hand just for the Spektrum guys.
Don't know why Futaba, Airtonics, & KO guys never need help

I'm an Airtronics guy & just run a but load of caps to make my servo super snappy & balance the chassis.

twoheadsbrewing

Sorry to derail the thread, just wanted to post back that it was actually a bad servo (S200). I guess it was failing and drawing so much power it was overcoming the BEC and therefore glitching and also causing the Rx to have issues. Amainhobbies swapped me out for a new servo and all is well!