Duet 2 maestro keep resetting power supply

Cecil

Hi,

I have just recently changed my hotend/extruder combo and I've started to have an issue on my Duet 2 Meastro. After turning on hotend heater my power supply keep restarting when hotend heater is driven by 100% duty cycle. Is there anything coming to your mind what can be causing this issue?
What I've found yet:

when I turn on bed heater everything is good and stable (without hotend heater). Bed heater is drawing ±8A
when I drive hotend heater max 50% duty cycle is almost without issues (didn't tried long print but ±30 minutes turned on and everything fine)
hotend connection OK, normal resistance, no short between wires, no short to heat block / thermistor
when try to disconnect hotend heater and turn on output of that heater it keeps resetting (time is not stable but between 2-5 second on and then 2 sec off)
use second heater output instead - same issue
current draw measured from power supply - 1.7A when turn on hotend heater that's perfectly normal
disconnected everything else from board (including extruder stepper, just bed heater, LCD, hotend thermistor (another one not from hotend) and XYZ steppers kept connected - same issue
visual check of board - no issue found

I have no idea what other to try, I think I have eliminated everything already

Phaedrux

@cecil said in Duet 2 maestro keep resetting power supply:

when try to disconnect hotend heater and turn on output of that heater it keeps resetting (time is not stable but between 2-5 second on and then 2 sec off)
use second heater output instead - same issue

So even with no hotend heater connected at all the board is resetting as soon as you try to enable the heater?

When you say the power supply is resetting, what do you mean?

Do the LEDs on the board go out?

Does it come right back up?

If you put your previous hotend and extruder combo back on, does it do the same?

After it reboots, can you send M122 and post the results?

Cecil

@phaedrux
Yes, exactly. When no heater is connected and I turn on heating power supply reset. It looks like over current protection triggered, but on the other hand, it's not immediately, it took 5-10 seconds, sometimes 2-3. When I connect multimeter and check current I cannot see any abnormality. Of course I cannot see short current spike but why would that happen? After 2 seconds power supply "protection circuit" reset and it start to deliver power again.
I haven't tried to install previous extruder/hotend combo because I reused some parts, but after disconnecting current hotend/extruder combo I got same results = power supply resetting.
I'm currently not using RRF, I'm using Klipper, but I'll try to get back to RRF and see if problem persist.

dc42

@cecil, my guess is that your heater cartridge has an intermittent short circuit, either across the element or between the element and the casing, that occurs when the element is hot. Try a new heater cartridge.

Cecil

@dc42 But it keeps doing also with disconnected heater. So it's switching power to open circuit and also it's failing.

dc42

@cecil said in Duet 2 maestro keep resetting power supply:

@dc42 But it keeps doing also with disconnected heater. So it's switching power to open circuit and also it's failing.

OK. Are you sure there is nothing conductive underneath the Duet that could be shorting the heater output pins together? Or some metallic swarf landed on top of the Duet?

The Maestro has two connectors per hot end heater output: a 2-pin Molex KK connector, and a 2-pin terminal block. Are you sure you have nothing connected to either of them?

Cecil

I really don't see anything what could cause the issue. And as I say it is strange because when I connect multimeter it shows me just 1.7A, only thing what could be causing it is some kind of current spike, but why?

Phaedrux

Are the heat sinks on the bottom shorting something?

Cecil

@phaedrux No, but I'll try o take them down. I haven't tried it yet. But they are there for a longer time than I have the issue.

Yesterday I put back RRF, I made some minor adjustment from last setting (for new extruder/hotend) and tried to calibrate PID on hotend. It made a good test because it's heating on full power. And it passed! 🥳 No issue at all!

Then without touching board I tried to heat hotend to change filament and crap! In like 5 seconds power down again!

Phaedrux

Might be a good idea to disconnect everything, take it out entirely and give everything a cleaning. Then test it on the bench.

Cecil

@phaedrux
I'll give it another try tomorrow. I thought it was fixed somehow, it worked now 2 days without issues, but today I came and again nothing was possible to print. It is really strange because first hour it was doing pre-heating fine but after that when homing and Z was triggered it shut down power supply. Then it become in a state i wasn't able to preheat. I disconnected everything keeping just power in, heater and thermistor connected and I still cannot preheat. I'll disassembly tomorrow also power supply and put it to bench and test there. Video from today here: youtube

Cecil

@phaedrux
Took the board out, cleaned with IPA, tried several heat cycles on bench without issue, assembled back, taking care every connection is good, printed for 4 hours without issues. Today after one 0.5 hour print it's back again.

Phaedrux

Do you have a different power supply to test with?