Heatbed not heating again
Yesterday I printed the default gear gcode included in 1.7.1. The entire print took a bit over 6 hours to finish. After about 4 hours the heatbed turned off. Today I checked and reseated the 15 blue fuse and the heatbed power connector which are clean and seemed fine and it still doesn't turn on. Previously I had an issue where the 3mm filament from the rambo box got loose ( http://shop.prusa3d.com/forum/original-prusa-i3-mk2-f23/heatbed-question-t953.html ) but I checked and it's still inserted correctly, and the zipties are tight and in the proper position.
Why would it work for several hours and stop if the heatbed connectors remain in place along with the 3mm filament? What else can I check? The printer is connected to this UPS (in case it matters):
http://www.amazon.com/CyberPower-CP1000PFCLCD-Sinewave-Compatible-Mini-Tower/dp/B00429N192
Re: Heatbed not heating again
Hi
From what I understand, the heater is now not working at all?
Did you confirm the fuse is OK? Do you have a multimeter?
The problem here is that there are several places where something could go wrong and you will need to troubleshoot from the fuse onwards and for that you will need a multimeter (a cheapie will suffice as you will be checking for 12V and continuity).
Check continuity of the fuse and the heated bed and then turn the printer and heater on and check for 12V across the heater connectors at the RAMBO and then the connectors at the bed.
Peter
P.S. the other option is to contact support - use the "Live Chat" on the shop pages and give them a link to this thread.
Please note: I do not have any affiliation with Prusa Research. Any advices given are offered in good faith. It is your responsibility to ensure that by following my advice you do not suffer or cause injury, damage…
Re: Heatbed not heating again
From what I understand, the heater is now not working at all?
Yes.
Did you confirm the fuse is OK?
I took the blue 15 fuse out and it looked clean and seated well. I also check for continuity and it beeped so it's ok.
Do you have a multimeter?
Yes.
Check continuity of the fuse and the heated bed
I checked that with a multimeter and it beeped so it has continuity. Sometimes the heated bed continuity check didn't beep but if I turned off/on the multimeter and tried again it beeped. For the heated bed test I put one probe on GND and one on VCC.
turn the printer and heater on and check for 12V across the heater connectors at the RAMBO and then the connectors at the bed.
The connectors at the bed are GND and VCC correct? Is the "heater connectors at the RAMBO" the power cable? How do I check for 12V using a multimeter? I use this multimeter: http://innova.com/en-US/Product/Detail/3320?r=0.6878525306348608
Do I place one probe on the black power cable near the rambo and one on the VCC connection at the bed? With the power plugged in is this safe?
P.S. the other option is to contact support - use the "Live Chat" on the shop pages and give them a link to this thread.
I was told by a chat person not to use chat anymore but to email directly which I have done with a link to this thread. Thanks for your help.
Re: Heatbed not heating again
OK, great
The heated bed should show continuity as it is only just over 1 Ohm. To measure the voltages:
Set the DMM to DC volts, at a scale above 12V and turn on the heated bed.
On the heater put the black probe on GND and the red probe on VCC The meter should read about 11.3 Volts with the heater turned on. If it shows less than 11 Volts then the problem is most likely closer to the RAMBo so at the RAMBo end, put the probes across the screw terminals of the heater connector. Again the voltage should be about 11.3 Volts.
Post your results and we will go to the next step.
NOTE: ensure that you don't let the probes touch when taking the voltage readings; that would definitely blow something...
Peter
Please note: I do not have any affiliation with Prusa Research. Any advices given are offered in good faith. It is your responsibility to ensure that by following my advice you do not suffer or cause injury, damage…
Re: Heatbed not heating again
The heated bed should show continuity as it is only just over 1 Ohm. To measure the voltages:
Set the DMM to DC volts, at a scale above 12V and turn on the heated bed.
The multimeter is auto only but I chose DC voltage.
On the heater put the black probe on GND and the red probe on VCC The meter should read about 11.3 Volts with the heater turned on.
It's close to 0, like 50mV. Since the temperature on lcd shows 0 and red led light doesn't come on this makes sense.
If it shows less than 11 Volts then the problem is most likely closer to the RAMBo so at the RAMBo end, put the probes across the screw terminals of the heater connector. Again the voltage should be about 11.3 Volts.
It's close to 0. I touched one probe to one screw terminal and another probe to the other one. I put it onto the heated bed connector like the one attached below. Just to check I tried the same for the extruder power and it was about 5V. Thanks.
Re: Heatbed not heating again
I disconnected the 2 psu cables, turned the power on, and multimeter showed both cables have 12V each. So if the fuse is good, how could it be that the power is not reaching the heatbed power connector?
Re: Heatbed not heating again
Yeah, good question.
You should see 12V on the extruder heater, but as it's working and you did get a reading then I don't think that's a clue.
If you don't get a reading across the screw terminals of the heater connector with the heater turned on, there are five possibilities that I can think of:
1. The heater is not turning on
2. The heater connector is not connecting
3. The solder joints of the heater connector are bad
4. The output MOSFET or other component has broken.
5. Some other issue
You say that the temp on the LCD shows zero. That should not be the case. The heater temperature should show RoomTemp/RequiredTemp
Which value is showing zero? If it's the room temp value, then the printer will not work as the minimum temp is 15 degrees (thermistor issue). If it's the required temp, then the heater has not been turned on.
Peter
Please note: I do not have any affiliation with Prusa Research. Any advices given are offered in good faith. It is your responsibility to ensure that by following my advice you do not suffer or cause injury, damage…
Re: Heatbed not heating again
1. The heater is not turning on
2. The heater connector is not connecting
3. The solder joints of the heater connector are bad
4. The output MOSFET or other component has broken.
5. Some other issue
Is there anything else I can do with a multimeter to check these potential issues?
You say that the temp on the LCD shows zero. That should not be the case. The heater temperature should show RoomTemp/RequiredTemp
Which value is showing zero?
I mixed up the voltage I was seeing which was near 0. As you note, the LCD was showing 25-29 degrees, room temperature, which is correct if the heater isn't heating.
When printing I noticed quite a bit of noise when it got to the top right section for some reason. Is that normal? Could that have caused something in the board to come loose?
Video of sound when printing from a few days ago: https://sendvid.com/8zuha7ob
What are my next steps? Thanks.
Re: Heatbed not heating again
Next steps...
Well we have to go through the list and eliminate each one in turn.
So just to confirm:
The thermistor is working and showing a bed temp of 25 degrees (or thereabouts) and when you set the bed temp to (say) 50 degrees, the LCD shows 25/50 but the heater light is not turning on.
The 15Amp fuse has been checked and is firmly in place in the socket.
Unplug the heated bed from the RAMBo, turn the printer on and set the bed to 50 degrees. Confirm the LCD is displaying BED: 25/50
with the DMM set to DC voltage put the probes into the heater plug on the RAMBo and note the voltage.
If the voltage is less than 11, probe the solder pads the back of the RAMBo where the heater connector is soldered. Again, note the voltage.
Turn the printer off, set the DMM to ohms (resistance) and put the probes on the heater connector. Wait for 5 seconds with the probes in place and note the reading.
Touch the probes of the DMM together, wait for 5 seconds with the probes touching and note the reading.
Post the 3 or 4 readings just to ensure they make sense and then we can go to the next step.
Incidentally, while the printer is turned on, can you just confirm the firmware version and variant. It may be a good idea to reload the firmware in case there is a problem.
Peter
Please note: I do not have any affiliation with Prusa Research. Any advices given are offered in good faith. It is your responsibility to ensure that by following my advice you do not suffer or cause injury, damage…
Re: Heatbed not heating again
So just to confirm:
The thermistor is working and showing a bed temp of 25 degrees (or thereabouts) and when you set the bed temp to (say) 50 degrees, the LCD shows 25/50 but the heater light is not turning on.
Correct.
The 15Amp fuse has been checked and is firmly in place in the socket.
Correct.
Unplug the heated bed from the RAMBo, turn the printer on and set the bed to 50 degrees. Confirm the LCD is displaying BED: 25/50
with the DMM set to DC voltage put the probes into the heater plug on the RAMBo and note the voltage.
12V
If the voltage is less than 11, probe the solder pads the back of the RAMBo where the heater connector is soldered. Again, note the voltage.
Turn the printer off, set the DMM to ohms (resistance) and put the probes on the heater connector. Wait for 5 seconds with the probes in place and note the reading.
Touch the probes of the DMM together, wait for 5 seconds with the probes touching and note the reading.
Post the 3 or 4 readings just to ensure they make sense and then we can go to the next step.
Since the heater plug on board gets 12V I assume I don't need to do this? When I plug back the heater connector into the board and check the screw terminals I see 0 volts so it looks like that is where the problem lies. However, when I view the connector it looks good, nicely screwed on etc. it does show I tiny black protrusion, not sure whether that's an issue. I didn't even notice until I looked at the photo.
Incidentally, while the printer is turned on, can you just confirm the firmware version and variant. It may be a good idea to reload the firmware in case there is a problem.
The support lcd section indicates: Firmware 3.0.0 (this was the default included automatically.)
RAMBo 13a
Re: Heatbed not heating again
Just my penny's worth, have you checked that the wire from the Rambo to the heatbed is not snapped inside? disconnect the connector at the rambo end and check the continuity (using either a continuity mode or resistance on the MM)... Hold one probe to the GND on the heatbed the other on the plug that would go in the GND socket on the Rambo normally... then repeat with the Vcc wire... It's fairly rare for a cable to break but it does happen...
Re: Heatbed not heating again
I just checked and continuity for both VCC and GND are fine. So based on my previous message I understand the issue some how has to do with the black connector piece that plugs into the rambo board. I get 12V testing the board directly. When I plugin the heatbed cable and test the screw terminals I get 0V. The kit included 2 extra black pieces should I just replace it? It looks fine to me based on the photo I previously attached. Except possibly for that tiny black protrusion. It's minuscule though.
Just my penny's worth, have you checked that the wire from the Rambo to the heatbed is not snapped inside? disconnect the connector at the rambo end and check the continuity (using either a continuity mode or resistance on the MM)... Hold one probe to the GND on the heatbed the other on the plug that would go in the GND socket on the Rambo normally... then repeat with the Vcc wire... It's fairly rare for a cable to break but it does happen...
Re: Heatbed not heating again
Yeah, that black but looks suspiciously like melted plastic.
However, what you can do is to put one probe in the end of the connector and the other on the screw; DMM set to resistance.
If you have Zero Ohms then it is simply a matter of plugging in and then push harder to ensure the connector is properly seated. If you have a reading over 1 Ohm, then best to swap out the connector if you have a spare.
Better still (and if you are feeling brave), you could solder the cables directly onto the solder pads on the underside of the RAMBo.
Peter
Please note: I do not have any affiliation with Prusa Research. Any advices given are offered in good faith. It is your responsibility to ensure that by following my advice you do not suffer or cause injury, damage…
Re: Heatbed not heating again
Yeah, that black but looks suspiciously like melted plastic.
However, what you can do is to put one probe in the end of the connector and the other on the screw; DMM set to resistance.
If you have Zero Ohms then it is simply a matter of plugging in and then push harder to ensure the connector is properly seated. If you have a reading over 1 Ohm, then best to swap out the connector if you have a spare.
It says 0.L which I believe is 0hms. However, I tried on the extruder connector and it is also 0.L so I must not be checking correctly. Do I need to forcefully push the probe into the connector? The power was off and the connector was disconnected of course.
Better still (and if you are feeling brave), you could solder the cables directly onto the solder pads on the underside of the RAMBo.
I have almost no experience soldering and would not be comfortable doing that.
Re: Heatbed not heating again
0.L means Open Loop or as you say 0 Ohms, which is what it should say. I agree that if you have spare connectors then swap one for this one and see if it fixes it, it may just be one of those weird quirks! That tiny little bump could in theory push the plug out of place and then sparks can form that cause residue that blocks the connections... So yeah, give swapping it for a new plug a try and tell us if it helps...
Re: Heatbed not heating again
0L usually means infinite; the opposite of zero and therefore the connector is not working; however, I don't think you have measured the right thing as you have the same on the extruder connector.
You need to probe the connector, one side at a time, between the screw and the point which plugs into the socket on the RAMBo.
Peter
Please note: I do not have any affiliation with Prusa Research. Any advices given are offered in good faith. It is your responsibility to ensure that by following my advice you do not suffer or cause injury, damage…
Re: Heatbed not heating again
It turns out that little black connector was the culprit. After swapping in a replacement it works fine now. I'm curious if, given this bad black connector, is there anything I can test with the multimeter that would show it doesn't work? Other than that tiny black dot it looks perfectly fine. Thank you very much for your help on this, what a relief!
Re: Heatbed not heating again
0L usually means infinite; the opposite of zero and therefore the connector is not working; however, I don't think you have measured the right thing as you have the same on the extruder connector.
You need to probe the connector, one side at a time, between the screw and the point which plugs into the socket on the RAMBo.
Peter
Hmm, it seems different meters use different terminology... handy to know, thanks Peter!
It turns out that little black connector was the culprit. After swapping in a replacement it works fine now. I'm curious if, given this bad black connector, is there anything I can test with the multimeter that would show it doesn't work? Other than that tiny black dot it looks perfectly fine. Thank you very much for your help on this, what a relief!
Glad you're up and running! Enjoy your printing!
Re: Heatbed not heating again
Yeah pleased you are back printing.
I guess you now understand what poor cable management can do...
Always ensure the connector screws are really tight, that the connectors are really firm in the sockets and that the cables are tied tightly at the support end points.
Peter
Please note: I do not have any affiliation with Prusa Research. Any advices given are offered in good faith. It is your responsibility to ensure that by following my advice you do not suffer or cause injury, damage…
Re: Heatbed not heating again
Hi,
my heatbed was failing last night during an 18 hour print. Nothing bad happend, print was successful. I followed the checklist in this thread, checked the screws on the connector at the rambo and it had voltage. checked the heatbed, no voltage. Then i pulled the cable at the heatbed and it fell off. Turned out it wiggled itself to death. Anyway, i soldered it back to the board and it worked fine. I checked the rambo and it seems we forgot to reattach one of the zipties after we rearranged the cables, that might have caused it.
Regards,
Constantin