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I've seen a couple possible solutions to this that I honestly haven't tried yet. Thought I could hopefully save some putzing around and a few hours of my life by asking here first.

Last night the HE280 showed up at my door and like a little kid at Christmas I started building it that instant and installed it later that night. As per the instructions I also upgraded the repetier firmware upgrade to 0.92.

The auto calibration worked flawlessly.
(Well, aside from my bowden getting caught up between an axis and an end stop every time it homes from the platform. Anyone have any suggestions for keeping that from happening?)

The next thing I tried was running some PLA through it, I used repetier-host to set the hot-end temp and squirt some goo through it. Worked fine.

It wasn't until I I was trying to figure out why I couldn't control the extruder w/ repetier-host that I encountered this issue. (I figured out that it doesn't turn on until it's at temp). I discovered that if I choose 'Preheat PLA' from the front panel the printer shuts off. Consistently, at anywhere from 15-20 seconds into heating up at which point I have to cycle the power switch to get it turn on again. Basically it's when it starts to heat up the build-platform + the hot-end.

This issue didn't exist until after the repetier upgrade / he280 install.

I'm running an original v2 built from kit w/ the 'stock' generic modded ATX power supply, stock cheapskates, stock arms, stock rambo board, etc, etc...

Are there some undocumented features/firmware settings/installation steps I need to know about?

Thanks!

My suspicion:
The ATX power supply is marginal, and when asked to not only power the slightly more powerful hotend heater, but also the PCB and additional fans, when it gets hit with the load of the bed suddenly it goes into over current protection mode, and shuts off. Have you tried warming the bed on it's own, and once it's up to temperature, then heating the hotend?

Nope, not yet... I can try that though.
I used to have a pico3d on there which uses a 40w cartridge heater, didn't have any problems... and I actually had more fans when I was running that... I have the original platform and stuff, so there was no room for that stack of fans.

Like you I have the new hot end but not ready to fire it up just yet, I am waiting for some more parts to remove some other mods before I can do some more!

I notice the xenocrates has a 760 power supply so maybe he is on to something....

Just watching to see how you go...

crocky wrote:Like you I have the new hot end but not ready to fire it up just yet, I am waiting for some more parts to remove some other mods before I can do some more!

I notice the xenocrates has a 760 power supply so maybe he is on to something....

Just watching to see how you go...

It was a notable problem that the ATX power supplies were sometimes flaky, and support would often replace them. Me being a computer geek, I had ATX supplies around. After I cooked the fuse in a lower end 750W (Heated chamber killed air circulation, it's not an issue of insufficient capacity or poor design on Seeme's part), I replaced it with a rather high end 760W, which should give you an idea as to how much strain is on these things, since the rambo can only pull 350W.

There is a reason most of the new printers have both a 29A supply and an additional fan in the side of the base. If heating the bed first works, that suggests it's not a Rambo problem, but a power supply issue, which can either be worked around like that longer term, as the amperage drawn by the rambo will fall as the temperature increases, as it has a positive temperature co-efficient, freeing up more power for the hotend, which heats much faster than the heated bed can in any case, or you can replace the power supply with either another ATX one (I personally use a Corsair AX760, which is a very solid unit, but somewhat expensive. It also doesn't fit hugely well, as it is a good bit longer than stock), or you can use something like the industrial supply SeemeCNC provides nowadays, and get their upgrade kit for it. If you don't want something like USB power jacks on your printer, and don't have something on say, 3.3 or 5V, then you probably want to switch to an industrial supply.

Yeah, so I happened to have a 625W supply sitting around so I wired it up and it fixed the issue with the shut offs.
Now I'm having issues with the firmware/rambo.
Also I noticed that nothing in the new firmware is configured for my version of the rostock with the oldschool carriages and arms... which includes the delta calibration stuff. Which seems important???????
So yeah, now I've had to scour through the configuration.h and replace all the stuff with the old values, which thankfully are still mentioned in the comments in the old v2 firmware, but the screen keeps going all wonky and garbled... so, yeah. This is going super well so far I think between last night and tonight it will be over 8 hours building, fixing, and dicking around to get this new hot end installed. And I'm still not done... Awesome.
So to the dude sitting back and watching this post, save yourself some hassle and just buy the power supply, arms & carriages along with your hot end...

Just for posterity & TLDR; the shutdowns were resolved with a new 625W power supply