2 heater faults, temp rising 2 slow, Temp excursion exceeded

nightpoison

I picked up a new to me D300VS recently. I've been trying to figure things out on it, but keep coming back to some heater faults.

I've done PID tests several times, always from room temperature. Heated bed heated up to operating temp, 60%. And the hot end close to the plate, fans on.

I will do a test print, just a simple first layer print, and I'll get a heater fault as its coming up to temp. Its always a temperature rising too slowly fault.

I can reset the fault and continue the print, and it will start to print. However, I also get a temperature excursion exceeded 15C (target 225, actual 245).

I'm getting a little frustrated with the heating operations.

My question is thus. What should I be looking at to correct this issue. Should I look at replacing the heater cartridge or the thermistor?

Here is my heater charts.

The first chart is the heater scaling up and then it appears to go crazy. Doesn't seem to be stable.

The second is the print over time, and then finally the spike I see when it throws the error.

here is my config file.

config.g

engikeneer

@nightpoison it would be unrealistic to expect those rapid fluctuations in temperature to be real (some of them are 50 degrees in half a second!), so the issue is on you're measurements.

I'd started by checking all your thermistor wiring & crimps from cartridge all the way back to the board. Most likely you have a partly broken wire or a dodgy crimp somewhere.

Looking at your temp plot at ~16:32, you are also getting some realistic instability at temperature. This is likely because your auto tune result was influenced by the connection issue.

nightpoison

@engikeneer

Ok, First step, recheck all wiring. Thanks for the first step. I'll check all the wiring, verify all connections. Hopefully I find something, I'll retest, and get back and repost my results.

nightpoison

@engikeneer Yea, so I found the thermistor wire and checked wiring and it looks good. Threw my multimeter on it, checked continuity and resistance. Resistance was lower than what my cheap multimeter could read. So I don't think there's any issues with the wires. I'm going to order a new thermistor, just to be on the safe side.

The hot end is using the standard thermistor cartridge. Is it worth it to grab the Pt100 thermistor upgrade?

engikeneer

@nightpoison PT100's are more accurate (you also get less piece-to-piece coefficient variation), and can go to higher temperatures. I've only ever used the normal thermistors though (mostly E3D thermistor cartridges) and never had a problem.

On the resistance/continuity measurements, did the value change at all when you flexed the cables? Can you see the rapid changes in DWC if you flex the cable in different places?

Another possibility is that the thermistor cables are picking up interference (e.g. from a stepper motor cable). You could try separating them from each other if they run next to each other for long lengths.

dc42

@nightpoison, from those temperature plots I suspect there is a problem with failing insulation in the heater cartridge and/or the thermistor cartridge. If it's not a cartridge thermistor, then a short between the thermistor wire and the hot end metalwork is a likely contributor.

nightpoison

@dc42 Hey, thanks for the input. The good news is that I have already ordered a new cartridge thermistor. The old one was also a cartridge, so I'll just be updating with all new wiring to be on the safe side.

@engikeneer had the notion that there might be some interference with the the stepper motor cables, I've actually picked up some shielding sleeves I'll wrap the wire in as well. Its probably overkill as there are 1k's of people running the wire without, but I figured what the hell.

The new Thermistor should be here today, so I'm hoping to have it wired up and testing today or tomorrow. I'll update as soon as I see some results.

nightpoison

@dc42 and @engikeneer,

Hello, thanks for the input and suggestions. I finally got the thermistor back in, and the hotend assembled. I kept running into issues, broke the heat break, the heater cartridge looked a little frayed and ended up getting the precision cartridge. So I replaced more than just the thermistor. Here is the new graph for the autotune this time around.

On to the next issues. Again thank you.