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Hi there,

I own a Rostock max v2, which I've upgraded with a HE280 hotend
I've run into a problem that appeared out of nowhere, well.., with small warnings.

For some time my printer wouldn't reach the right temperatures in the first few layers, slowing down the layer fans helped, but I thought that wasn't a lasting solution. So I insulated the heater block with kapton tape and noticed air was leaking from the barrel fan down towards the heaterblock, so I closed it off with more tape. Then I looked up the problem and found that this was a known problem and thus I applied the known fixes, Since I also encountered the problem of the whip plug disconnecting I also printed and installed a Whip clip. Before I encountered some mid print or preheating Def's replugging the whip and rebooting the printer helped.

Then I successfully printed some nice prints, all worked well and I was really happy, since I also reached perfect bed lvl calibration. Then I thought, since I've executed all of these fixes and calibrations, lets recalibrate the PID's while we're at it. But even before I started this process while pre-heating for a print, I got another "def" on temperatures. Replugging the whip and rebooting the printer didn't help this time. I tried all simple fixes I could come up with, and rebooted a lot of times and replugged the whip quite often, even waited a few days to retry, nothing works.

So I'm thinking my heating resistor is broken, since the thermisistor works fine (when I hold the heaterblok for a few minutes the temperature goes up).
The Bed heats up fine, so it must be the heating resistor or the fuse? or the writing of either.

So three questions:
1. What do you think?
2. How do I go about finding the exact problem?
3. Can I replace the heating resistor by one that is locally (Europe) available but 23mm long instead of 15mm?

I found one with the following specifications:
Lengte: 160 cm
Voltage: 12 V
Power: 40 W
Cartridge length: 23 mm
Cartridge diameter: 6 mm

Does the hot end heat properly before the thermistor conks out ("def" on the display)?

g.

Nope, when I for example start the standard PLA preheating sequence from the menu, the bed starts to heat, but the nozzle doesn't. It's not that the temperature sensor doesn't register, it stays cold to the touch.

To make sure it's the heater (which it's not too likely to be, since it worked in the first place), use a multimeter to check the voltage drop from one side of the fuse to the other. If it's near zero, it's the heater. Anything else, and the fuse needs replaced. If it is near zero, check the voltage across the heater. If it's ~12V, then replace the heater, since it's not heating. If it's not, check the rest of the heater wiring.

Thx for the help!

I checked the voltage drop and up till the heater, 12.8 V is supplied, but after the thermal fuse it drops to 0. So that would mean the fuse needs replacing. As final check I Bypassed the fuse and that solved the problem. I removed the fuse to get a better look at it, so I could determine the right replacement. But wile doing so, I noticed that the clamping tube that connects the heater to the fuse, wasn't holding the wires together that well. I measured the resistance of the fuse which was 0, indicating that it should still work.
Replacing the metal sheeting and clamping it better solved everything!! for now at least

Thx for the help again!