abrupt temperature failure at same postion?!

[rabbit]

Me again...
I am so frustrated!
Now I have an new issue:
When I try to print a big model each time the print reaches something around layer 4 the temperature of the hotend dropps till the LCD shows "def" like the whip was disconnected. But it isn't the wiring. When I switch off and on everything is ok again.
I used Mattercontrol and Cura out of Mattercontrol to slice.
Both with the same result.
Has anybody an idea what could cause this?

By now I regret installing the upgrades on my Rostock.
It ran so smooth... now there is trouble after trouble.
Maybe I switch back to the old hotend

[geneb]

If you have a problem like that at a specific height, it's a wiring issue.

g.

[rabbit]

Thank you for your answer geneb,

I know what you have in mind. But I don't think that is the reason here.
The calibration box prints out perfect. And there are some more layers to reach...
I am so under time pressure that I threw out the H280 and installed the old hotend back in.
With the old whip...
Guess what! Same thing happend here!!!
Could it be a problem with the rambo? When I switch off and on everything seems fine again.
so frustrating...

[Polygonhell]

It's very unlikely the issue is with the RAMBO.
When the A/D pins on the arduino get damaged they usually just stop working altogether, it's a really simple circuit, just a simple voltage divider running into an A/D pin, I can't think of a failure mode where it would be intermittent.
The fact that when you power cycle it stops reading def isn't really informative, and doesn't rule out wiring, once it faults it will read def indefinitely until the power is cycled.
Most likely something is straining in the wiring during some move, which is resulting in the thermistor faulting for a very small window.
One reasonably common thing I've seen happen is the wiring gets caught round one of the carriages during a move.
In line connectors can also fault this way, especially the JR style dupont connectors, I had one inline on a stepper that took me hours to find was at fault.

[rabbit]

solution seems to be found:
it is the power supply! I have still the old ATX installed and it seems to be giving less power.
jj from seemecnc gave me the great advise to change PID settings: PID Drive Max to 255 and the PID Max Value to 255
till now my rossi is running again.
strange thing is have no extras installed to consume more power