Ramps 1.4 cuts off when servo moves

ok here goes nothing

i start the print no usb plugged in and everything heats up great, steppers move fine, but when auto leveling starts and the servo goes to move in to place the printer shuts off then back on.

when the usb is plugged in everything is working fine.

anyone have thoughts on this? before this happened it was running fine then started running off to one side randomly in a print. not sure if this has to do with this problem.

Don't use the +5V from the Arduino to power the servo. This is explained in the wiki.

i'll check that out thank you

i looked in the wiki and did not see anything on it am i looking past it? please help

[reprap.org]

Specifically (emphasis added):

The 5V pin in that connector on RAMPS only supplies the 5V to the auxiliary servo connectors. It is designed so that you can jumper it to the VCC pin and use the Arduino's power supply to supply 5V for extra servos if you are only powered from USB or 5V. Since there is not a lot of extra power from the Arduino's power supply you can connect it directly to your 5V power supply if you have one. You can also leave this pin not connected if you have no plan to add extra servos.

i found it...

due to me using a LED strip power supply i need to get a 12v dc to 6v dc converter to run the servo off of. at least this is what i'm reading on another page. this will also stop the servo chatter that a get wile printing. just not sure if this is the best way to go still looking around.

Or you could get a good quality atx pc power supply to run the lot.
The servo's will happily run of the 5v supply from there.
Apart from one duff power supply i salvaged from an old pc case ive had no problems running my machine with a hested bed.
So buy new.
Modern supplies have two 12v rails so you can use one for the bed and one for the nozzle and electronics.
Youve then got a stack of 12v and 5v supplies for other uses.
Read the reprap wiki, follow the instructions and make sure you put a resistor on one of the 5v rails to regulate the power.
All in the wiki.

Gordon

Keep your existing LED power supply. There's no reason to pay the extra for a decent ATX power supply that you may have to jump through hoops to output it's rated power just to get a few hundred mA of 5V. Just get a buck-boost power supply to efficiently regulate the voltage down to 5V. Search "LM2596" on Amazon or Ebay for a bunch of options for a couple of bucks.

I got the impression he was on the limits of his existing supply.
With the 2 12v rails on modern atx supplies your effectively getting 2 power supplies plus the other power rails..
The only fiddling is sticking a cheap chunky resistor on the 5v rajl and attach it to the case to disipate heat.
I bought some cheap extension cables for the atx plugs and extended them to the printer.
No hacking of cables either. Its not a messy solution anymore.

Gordon

i found a 12v to 6v converter on amazon i went ahead and got 2. i'm going to run the power off it to the servo and bypass the board. think i paid about 5$ for these not too bad and i think this will fix all the problems on the servo end

i can get a link to the converter i got if anyone need

Connecting a 6V powered servo to the 5V logic from the Arduino can eventually damage the Mega chip, fyi.

its a 4v-6v servo

[www.ruggedcircuits.com]

Method #3

Quote
AndrewBCN
[www.ruggedcircuits.com]

Method #3

This presumes that the signal has the chance to backfeed the microcontroller via the signal line. Depending on the servo, the signal wire may be effectively isolated electrically so that the servo's supply voltage can't backfeed the pin.

Quote
gordonendersby
I got the impression he was on the limits of his existing supply.

No, he's using the Arduino's regulator to produce the 5V to power the servo which can produce the results he's experiencing. When he plugs in the USB cable, the 5V is pulled from the USB connection bypassng the regulator. My guess is that he's right at a threshold where the regulator struggles, but the USB connection doesn't for whatever reason.

Quote

With the 2 12v rails on modern atx supplies your effectively getting 2 power supplies plus the other power rails..
The only fiddling is sticking a cheap chunky resistor on the 5v rajl and attach it to the case to disipate heat.
I bought some cheap extension cables for the atx plugs and extended them to the printer.
No hacking of cables either. Its not a messy solution anymore.

Many power supplies still need the resistors though. A 4.7 ohm power resistor on the 5V rail to provide the power regulation is using about an amp of current and needs to dissipate 5 watts unnecessarily. It's not going to break the bank, but it's an unnecessary loss. And if you don't happen to have the resistor laying around, buying one online probably is going to cost as much as just getting a cheap buck-boost power supply.