Hotted not maintaining temperature April 01, 2016 09:27PM |
Registered: 7 years ago Posts: 8 |
Re: Hotted not maintaining temperature April 01, 2016 10:09PM |
Registered: 8 years ago Posts: 1,873 |
Re: Hotted not maintaining temperature April 02, 2016 12:08AM |
Registered: 7 years ago Posts: 8 |
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JamesK
You have 40W 12V heater cartridges? Trying to maintain a 210 degree temp. It'll drop down to 200 or so recover to about 205 and then usually starts dropping below 200. I've temporaly disable the thermal_protection_hotends so it wouldn't fault out on Thermal runawy alarms. At least I can see it seems to recover a bit.
Resistance should be about 3.6 Ohms. What temperature are you trying to maintain? Assuming it's not something ridiculous, if you have 3.6 Ohms for the heater and 12V at the ramps the only logical explanation is a broken wire. I would suggest the crimps where the wires are connected to the solid cores coming out of the cartridge - I had a loose one that behaved very much as you describe. But if you changed the cartridge you'd have to be very unlucky to have both of them be loose. You could check the screw terminals at the ramps end and any connectors between them and the heater. If nothing is obvious, run a new cable between ramps and heater and see if that solves the problem.
Re: Hotted not maintaining temperature April 02, 2016 02:51AM |
Registered: 7 years ago Posts: 8 |
Re: Hotted not maintaining temperature April 02, 2016 08:14AM |
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Re: Hotted not maintaining temperature April 02, 2016 08:22AM |
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Re: Hotted not maintaining temperature April 02, 2016 01:15PM |
Registered: 7 years ago Posts: 8 |
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JamesK
Yes, the straw supply is starting to get a bit short. When you measure the voltage, where exactly are you measuring between? The mosfet heater circuits are switched on the negative side, so people occasionally get confused by measuring between supply 0V and the heater + terminal on the ramps, but that will always read the supply +V value (unless the poly fuse is cutting out). If you measure between supply 0 and the heater - terminal on the ramps it should show 12V when off and close to 0V when on.
How is your setup wired up? Are you using the 'normal' connections for heatbed, extruder and part fan or have you swapped anything around? And you have both sets of 12V inputs connected, and those connections are solid and not overheating?
I've had problems with poor thermal conductivity between the heater cartridge and the heater block, using a cheap one with an oversized hole and the cartridge held in place with a set-screw. That was improved hugely with some Z5 thermal grease, but it also showed up as an inability to autotune the pid, and you've said that works ok.
Do you use a heated bed? If so, your power supply must be capable of way more than the hotend needs, but if not, maybe the psu is struggling. Definitely clutching at straws now...
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JamesK
Given that we're running out of hardware possibilities, you might want to consider throwing Repetier firmware on the board for a quick test. One of the things I feel Repetier does better is thermal control, but the main point would be to try a completely different firmware and see if it behaves the same way or not. There's a relatively easy to use online configuration tool which provides a download link as the final step: [www.repetier.com]
If you can get past the ugly home screen and unfamiliar menu structure you might even find you like it
Re: Hotted not maintaining temperature April 02, 2016 01:28PM |
Registered: 8 years ago Posts: 1,873 |
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I'm measuring across the +/- terminals where the heater is connected at D10 I get 0vdc when it's idle up to 11.7vdc when it's driving the hot end hard, I've never seen a full 12v measuring at that point.
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I'm only using the 5
Re: Hotted not maintaining temperature April 02, 2016 02:07PM |
Registered: 7 years ago Posts: 8 |
Re: Hotted not maintaining temperature April 02, 2016 03:39PM |
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Re: Hotted not maintaining temperature April 03, 2016 02:05PM |
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Re: Hotted not maintaining temperature April 03, 2016 02:11PM |
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Re: Hotted not maintaining temperature April 03, 2016 03:57PM |
Registered: 7 years ago Posts: 8 |
'Quote
JamesK
I've had a problem or two like that. It's unsettling to say the least. I must admit, when sigxcpu suggested the fan I thought that was it, and I'd over-looked the obvious. Not sure if it's good or bad that it turned out not to be the problem!
Re: Hotted not maintaining temperature April 03, 2016 08:56PM |
Registered: 8 years ago Posts: 778 |
Re: Hotted not maintaining temperature April 08, 2016 01:29PM |
Registered: 7 years ago Posts: 8 |
Re: Hotted not maintaining temperature April 08, 2016 01:51PM |
Registered: 8 years ago Posts: 1,873 |