Ramps 1.4 Heat Problems

Hey everyone.

I have a FLSUN i3 Prusa clone that I had to replace the board on a while back. I don't use it much these days so I dug it out to resurrect it. The problem I'm having is that since hooking it up with a Ramps 1.4 board the hotend and bed (mostly hotend) get a lot of temp drops. While printing it starts fine, but after maybe 5 minutes it will start to get these little sudden drops, then back to normal temp, then a drop, then normal. They're very sudden and not a smooth return to temp, it's like it thinks for a moment it's a lower temp, then it jump back up. Eventually the temp graph starts to look like a rapid heart beat with it dropping, then jumping back to normal for a moment.

I've used two different Ramps boards and arduinos, same problem. I've added a separate mosfet for the bed, a fan for the board, etc. Nothing seems to make a difference.

If anyone has seen this before any info would be appreciated. I'm to the point that I'm just going to savage this printer for parts if I can't rely on it to get through a print without quitting.

Thanks!

A broken or failing wire, thermistor or thermo couple springs to my mind first. Or you need to do auto pid tuning on the hot bed, possibly on the bed as well. Did you try replacing the temperature sensor?

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Kind regards
Imqqmi

NFAN CoreXY printer:
[reprap.org]

Hey,

I've replaced the thermistor a couple times (was using an authetic E3Dv6 thermistor, then a knockoff that was very broken, then a standard one). First and second both had the same results.

I've checked the wires over and over, I've had the board completely unplugged and replugged, two different boards, and still no luck. The auto PID I've run multiple times as well.

I'm very confused by it, haha. It started as soon as I went to a Ramps board.

Quote
imqqmi
A broken or failing wire, thermistor or thermo couple springs to my mind first. Or you need to do auto pid tuning on the hot bed, possibly on the bed as well. Did you try replacing the temperature sensor?

Just reporting back that I tried upgrading my firmware and so far so good. It's made it farther than it ever has without a blip so we'll see what happens. I was running 1.1.6 on there and realized I hadn't tried changing it out while swapping around all the hardware. If it doesn't fix the problem I'll be back but I'm hopeful!