mk3 problem. I need advice!
History: I just received the mk3 and assembled it 2 weeks ago. It was working perfectly. No problems. 1 week ago I started a print and went to bed. I awoke to a machine that had stopped printing and stated thermal runaway on the LCD. It would not heat. I replaced the Hot end assembly which included the extruder and hot end cartridge and thermiresistor wiring. The 5 amp fuse was blown so I replaced it.
The problem I need help with is that now the extruder heats up beyond set temperature and keeps going. I blew another fuse before I realized it. Now I have gone over the placement of where I plugged everything into the board. It is correct. Is there circuitry on the board I need to examine?
Re: mk3 problem. I need advice!
Hi Jacob,
if your printer has been overheating, it is possible that the extruder housing plastic parts have been damaged already.
during these checks, make sure that your left hand fan is running whenever the temperature is at or above 50 degrees
there are three active parts to the heating of the extruder...
one is the heater, the others are the thermistor and the einsy control board. your extruder is getting hot, so that suggests the heater was working.
if you turn the printer on (from cold) do you still get a temperature display on the LCD?. (beware of the heater temperature running uncontrollably higher)...
currently mine is showing 17 degrees for both the extruder and the heatbed. this is reasonable because there is no central heating on at the moment.
if the extruder temperature reads low it is possible that your thermister is faulty, or incorrectly plugged in... my printer reads about 11 centigrade if the thermistor is open circuit! but other folk have reported higher temperatures...
if the extruder temperature starts climbing uncontrollably, it's likely that you have a wiring fault or your einsy is faulty(if this happens, turn the printer off, and investigate fully... perhaps with help from Prusa echat!)
if you use a hair drier or hot air gun, to heat the extruder heat block GENTLY(you don't want to melt the plastics)... you should see the extruder temperature start to climb...
this is showing that your thermistor is connected and working to a degree.. let the extruder cool again...
if the temperature for the extruder does not increase you have a fault either on the thermistor or the Einsy board
if I use the LCD Menu to select settings, then temperature, then nozzle, and set the temperature to 50 within about 10 seconds the extruder temperature had climbed to 40 degrees. at about 15 seconds the temperature reached 50 degrees and the left hand fan turned on, the extruder temperature did overshoot to 57 degrees and then settled down back to 50 degrees, this showed that the einsey was controlling the heater temperature.
does yours do this?
if this works, it suggests that your einsy, heater and thermistor are working...
let us know how you get on.
regards Joan
I try to make safe suggestions,You should understand the context and ensure you are happy that they are safe before attempting to apply my suggestions, what you do, is YOUR responsibility. Location Halifax UK
Re: mk3 problem. I need advice!
Ok! I think I'm getting somewhere! Thank you for the input! It got me going.
Here are my tests and findings:
To start, the extruder and bed were the same temp 22c
I applied my soldering iron to the extruder to see if the temp changed. Success, it did.
test 2: I went to settings and temperature and set the nozzles to 25c. The temp increased and over shot by 3 degrees and slowly came down.
- I then set temp at 30c and the temp increased and over shot to 3c and slowly came down.
-I then set temp at 50c and the temp increased and over shot to 84c. The fan came on and brought temp back down more quickly.
-I then set temp at 120c and the temp increased and over shot to 167c. The fan was on and temp came down
Observation- When I initially fired up the MK3 after assembly, the bed and extruder increased at about the same rate... maybe the extruder moderately faster. Now, the temp shoots up on the extruder almost as fast as I can change screens back to the info screen.
thoughts?
Re: mk3 problem. I need advice!
Run PID tuning on it (in the menu someplace). and the bed is always slower. also they won't heat at the same time depending on the temps... bed first then nozzle usually.