Cold end fan troubleshooting  

Re: Cold end fan troubleshooting

I'm not an expert but if it was me I would just replace the fan. From what I've read in this forum so far they fail often anyway.

Re: Cold end fan troubleshooting

I just started having this problem yesterday. I believe it has to do with a connection in the wire harness.

Do the following.

-Take note of the X,Y,Z position when the fan turns off.
-After you print is finish, unload the filament
-Heat the hot end so the fan just come on, I think the temp is 60C
-Move the print head to the X,Y,Z position when the fan was cutting out

If you can get the fan to cut out, wiggle the wires harness going into the print head. Does than fan come back on?

If you discover anything post back to this thread. I've started a thread on possible resolutions to this issue:
http://shop.prusa3d.com/forum/prusa-i3-kit-building-calibrating-first-print-main-f6/after-45-days-of-continous-printing-1st-maint-need-t3107.html

Re: Cold end fan troubleshooting

I found the problem and Fixed it!

Sorry, I couldn't take pictures...

I found that the problem was that the black fan cable was internally cut where the zip tie that attaches to the back of the extruders and the cable bundle first comes out.

I have a picture of this from the Extruder Assembly step 35

I soldered the wire put some new shrink wrap moved the wire so it doesn't happen again and put new zip ties

Realistically it will happen again with this or even worse with a different wire. Maybe I am doing something wrong but you can see the stress point when you move the wire or the extruder to one side to the other. Now I am really contemplating cable chains but I really would like to avoid them.

Re: Cold end fan troubleshooting

I too had cold end fan problems... this may be related to the layer shifts I suffered on my last big print,

I am so glad that it didn't happen earlier.

it would have made a mess of the 30+ hour print that I was doing...

In my case, the fan speed was up and down like a fiddlers elbow, and I noticed the Hot End temperature was also up and down like crazy.

I thought it was a faulty thermistor, and when I dug in, the hot end was a mess of burned filament and what have you.

as My second Prusa kit has recently arrived, I decided to swap out the hot end for the more up to date heatsink version.

I have also fitted the silicone boot in the hopes of keeping things, cleaner and getting away from Thermal Runaway...

so. whilst I was at it, I upgraded from 3.0.8 to 3.0.9 re calibrated and started a test print... all was well a couple of minutes ago, so I will let it move along. whilst I investigate how to tune the PID...

regards Joan

Oh, and I have ordered a new hot end, boot, heater and thermistor, to sort the second printer...

Re: Cold end fan troubleshooting

What heatsink version hotend are you talking about?

I have been using the silicon sock since day one and I haven't had issues with thermal runaway. What did you end up doing with your fan?

Also, I am envious of the fact that you have 2 Prusa MK2's

Re: Cold end fan troubleshooting

Same for me. My printer had been working great until this week! More times than not now, I am getting a THERMAL RUNAWAY shutdown now, while it is printing out the BRIM on the parts. I've got the cable chains, and am about to switch back to the original cable looms. I will inspect my wiring as you suggest...

Chris

Re: Cold end fan troubleshooting

Before you change out your cable chains, consider running your prints with a lower part fan speed...

on my printer the part fan was occasionally causing the hot end to cool faster than the heater could heat it.

net result the printer tries to maintain the temperature, the thermistor records the temperature dropping, software thinks there is a problem, and issues a thremal runaway error, and stops the print.

Regards Joan

Re: Cold end fan troubleshooting

I have a silicon sock over my hotend and I have never had thermal runaway. Not sure that this is the sole reason as to why but it can't hurt