Spektrum RX internal "glitch buster" cap mod - RC-Monster Forums

simplechamp · 09:25 PM

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.

bdebde · 03.01.2011, 09:22 PM

Very nice, great idea, I like it!

simplechamp · 03.01.2011, 09:35 PM

Simple and effective, the way things should be! Spektrum should build them like this from the factory given how much current today's servos draw. They did put a cap on the board across the + and - pins, but it's only 100uF. Probably more for noise reduction than stabilizing voltage.

simplechamp · 03.01.2011, 11:32 PM

Here's the finished SR300. You can see the cap on the left side. Added the antenna tube holder, and swapped the green LED for a red one to match the accents/hardware on my Jammin GT.

snellemin · 03.02.2011, 11:58 AM

Nice mod.

Shonen · 03.02.2011, 03:29 PM

looking good, but I would recommend using an adhesive that isn't CA based when it's that close to electronics.

http://www.teamnovak.com/products/in...ca_warning.htm

Tintman · 03.02.2011, 05:39 PM

Very nice, great idea..

What's_nitro? · 06:02 PM

I like it. I think I'll copy you and change the LED color on my Rx, too.

Edit: I'm gonna use one of those crazy RGB cycling LEDs.

BrianG · 03.02.2011, 06:16 PM

This is a neat mod! Unfortunately, almost all my Spekky receivers are the older opaque gray box style where there are two PCBs inside, so no extra room for a cap.

For future reference, those empty solder holes on the edge may be an alternate place to solder the cap. I can see there is at least a ground point, and I imagine there is a power point there too (would have to do some circuit tracing to be sure).

lincpimp · 03.02.2011, 06:16 PM

Quote:

Originally Posted by What's_nitro?

I'm gonna use one of those crazy RGB cycling LEDs.

Hope you do not get near an epileptic kid, those things are like time bombs!!!

simplechamp · 06:30 PM

Quote:

Originally Posted by BrianG

For future reference, those empty solder holes on the edge may be an alternate place to solder the cap. I can see there is at least a ground point, and I imagine there is a power point there too (would have to do some circuit tracing to be sure).

I was actually just about to ask what those were for. Might have to open it back up and do some more snooping around.

Quote:

Originally Posted by Shonen

looking good, but I would recommend using an adhesive that isn't CA based when it's that close to electronics.

http://www.teamnovak.com/products/in...ca_warning.htm

That's good to know for next time. I really only used like 2 drops, so hopefully it will be OK.

What's_nitro? · 03.02.2011, 06:38 PM

Quote:

Originally Posted by lincpimp

Hope you do not get near an epileptic kid, those things are like time bombs!!!

The LED or the kid?

BrianG · 03.02.2011, 08:18 PM

Quote:

Originally Posted by simplechamp

....That's good to know for next time. I really only used like 2 drops, so hopefully it will be OK.

Hot glue works well...

Shonen · 03.02.2011, 09:19 PM

Quote:

Hot glue works well...

hot glue works very well (: it's what I use to mount LED's in body shells, and it can be pulled off if necessary. It's cheap, too.

ps. hot glue also 'carries' light very well if you shine an LED in it.

BrianG · 03.02.2011, 11:17 PM

I personally like it because it is translucent like you said, it is also somewhat flexible, and can be removed if needed. However, it is NOT nice when it gets on your fingers.