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I'm trying to get the E3D V6 hotend to 228 and the bed to 90. It won't happen. Hotend stops at 225.6 and bed around 80.

Playing around, I took the bed to 90 with the hotend set at 150. Bed got to temp. Then set the hot end to go to 228. It wouldn't go past 225.6 (actually bounces between that and 226.1). Then I turned the bed heat off and the hot-end immediately jumped to 228. Just playing, I then set the hot end to 260 with the bed temp off and it got to 258.6. Finally, I tried 255 and that went to 253.3.

Story of my upgrade.
Did something amazingly stupid and cut the wires to the stock hotend without powering down (at least I assume that is what happened). Anyway, when I cut the wires, a bunch of sparks flew and I blew fuse F3. Got a replacement fuse and everything seems to be working fine other than this temp issue. I did the PID calibration and I'm unsure if that is the problem. On the one hand I can get the hotend to lock on 228 as long as the bed isn't being heated, on the other, I couldn't quite get to lock on at 255 or 260 (I did the PID tuning at 240). One other thing to note, it seems like the power supply fan is now louder than it was before (I don't remember noticing it before, now it is very present (wouldn't miss the noise now and try to cut wires while powered on:( )

Setup.
Mostly stock Rostock Max V2 kit from October 2015. I don't have the newer power supply. E3D hotend installed with fan blowing at 100%. Set EXT0_TEMPSENSOR_TYPE 8 and MAXTEMP to 300 in configure.h and uploaded. I do have tricklaser LED light ring installed in parallel with the fan, but that has been there for a long time with no problems. At the same time as I installed the hotend, I upgraded to 0.92.2 of the firmware (from https://github.com/seemecnc/Firmware) (next thing I think I'll try is downgrading the firmware back to 0.91)

So I'm thinking I've done something to the power supply. Couple questions.
1) With the stock power supply, should I be able to power and E3D to 228 and bed to 90? (assuming yes since I could with stock hotend)
2) I've not heard of partially reducing a power supplies max capacity from a short. Is that a thing that can happen?
3) If I need to replace the power supply, I might go to 24V. Any good write-ups on how to do that for the Max V2? What are the advantages?
4) Any other suggestions on what could be wrong?
5) Any suggested diagnostics I could do on the power supply?

Thanks for your time
John

1) Yes.

2) yes, but that's probably not the problem (and with these supplies, you would more likely kill it than reduce capacity)

3) There are a couple of write ups. The advantage is a lot faster bed heating and smaller wires needed to supply other things, as well as potentially faster stepper motion (Only starts mattering with .9 steppers in most cases, as hotend speed is your limit most of the time). It has some disadvantages, namely a worse selection of fans, few accesories will accept it, and you lose the auxilary voltages an ATX supply offers.

4) I suspect what you're encountering is voltage droop. Tune the hotend at ~245, 250, while the bed is running. If it won't tune, crank the "EXT_1_PID_Drive_Max" or something to that effect to the maximum and try again.

5) you can get an ATX supply tester and use that. Another possibility is to use a voltmeter or multimeter to check what the voltage is at the hotend while at temperature, as well as at the screw terminals.

Let me know how it goes. And please, unplug the machine before doing electrical work in the future (or keep a hand behind your back). I'd rather not hear that you've ended up dead (12V is in theory not enough to kill you, unless you jam it into your fingers enough to bleed, but DC is unfun to touch)

Xenocrates wrote: Let me know how it goes. And please, unplug the machine before doing electrical work in the future (or keep a hand behind your back). I'd rather not hear that you've ended up dead (12V is in theory not enough to kill you, unless you jam it into your fingers enough to bleed, but DC is unfun to touch)

just as a warning for anyone reading- it's not the voltage that kills, it's the amperage.

TwoTone wrote:

Xenocrates wrote: Let me know how it goes. And please, unplug the machine before doing electrical work in the future (or keep a hand behind your back). I'd rather not hear that you've ended up dead (12V is in theory not enough to kill you, unless you jam it into your fingers enough to bleed, but DC is unfun to touch)

just as a warning for anyone reading- it's not the voltage that kills, it's the amperage.

And amperage is largely a function of voltage and resistance, thus why 12V (or 9) can be lethal if you end up with it making contact with the bloodstream, as that is much lower resistance than skin. I am informed the navy has an internal incident report on such a thing happening. The supplies involved here are not current limited, and with lethal amperage being ~100 mA, and the cannot let go range being 10 mA, one shouldn't be permanently by touching it given normal human skin resistances, or even really feel it. However, one should build good habits, especially as sloppiness can blow fuses, components, or if you extend it to other wiring, kill you. I tend towards encouraging people to be more cautious than strictly needed, and if they take the time to become more educated and realize that that little HV supply can only do a few microamps, and so should be mostly safe, or that even 48VDC shouldn't kill them, but would mess up their day if they had wet skin, then they have learned something and I don't feel like I may have encouraged people to do something unsafe

Thanks!

So looking at the code, all heaters are turned off before auto-tune starts, so it seems like it shouldn't matter what the bed temperature is. Having said that, I did run the bed up to 90 and then run auto-tune at 245. The D value was much larger than I'm used to and watching the extruder temperature as it settled, there was more oscillation in the temperature than I like, but at least now I can get to 228/90.

Of course the whole point of upgrading to an E3D was to move to PET-G which wants 220-260/80-100 from my reading, so still need to play, but at least now I'm where I was before the upgrade.

And yeah, cutting wires without pulling the plug is a dumb-ass move that I'm still shaking my head at. I've had a soldering gun in hand for more than 30 years. I know better. The dangers of "unconscious competence" strike again.

One last follow-up. It looks like the real magic was bumping the Extr1. PID drive max in the EEPROM to 255. Did that while the printer was struggling to achieve the correct temperature and it then bounced up like I wanted.