Extrusion Heater is on unexpectedly and heats up at power on.
22 views
Skip to first unread message
kidNeutrino
May 19, 2011, 12:42:17 PM5/19/11
to MakerBot Operators
Extrusion Heater is on as soon as the ToM powered up. We disconnected
the wires on the EC and the readings went to normal. I fear that the
thermocouple has lost insulation and is connecting to the block. I
read 2.8ohm on the disconnected heater wire. I tried to read a short
by metering the heater wires to the thermocouple wire to confirm the
short. I get a reading of 1.2 ohm from touching the thermocouple
yellow and red heater wire.
Whadddya think?
Will the blankets survive me dissecting the head?
thanks,
the wires on the EC and the readings went to normal. I fear that the
thermocouple has lost insulation and is connecting to the block. I
read 2.8ohm on the disconnected heater wire. I tried to read a short
by metering the heater wires to the thermocouple wire to confirm the
short. I get a reading of 1.2 ohm from touching the thermocouple
yellow and red heater wire.
Whadddya think?
Will the blankets survive me dissecting the head?
thanks,
B Stott
May 19, 2011, 3:41:21 PM5/19/11
to make...@googlegroups.com
Yes, doctor - the patient will live. Cut carefully and re-tape gently.
--
You received this message because you are subscribed to the Google Groups "MakerBot Operators" group.
To post to this group, send email to make...@googlegroups.com.
To unsubscribe from this group, send email to makerbot+u...@googlegroups.com.
For more options, visit this group at http://groups.google.com/group/makerbot?hl=en.
kidNeutrino
May 19, 2011, 4:20:30 PM5/19/11
to MakerBot Operators
LOL, there _is_ a reason I didn't go into surgery.
kN aka Shakey McShakes
On May 19, 2:41 pm, B Stott <sto...@gmail.com> wrote:
> Yes, doctor - the patient will live. Cut carefully and re-tape gently.
>
kN aka Shakey McShakes
On May 19, 2:41 pm, B Stott <sto...@gmail.com> wrote:
> Yes, doctor - the patient will live. Cut carefully and re-tape gently.
>
Ed Nisley
May 19, 2011, 4:32:55 PM5/19/11
to make...@googlegroups.com
Extrusion Heater is on as soon as the ToM powered up
That suggests there's a problem with the MOSFET on the Extruder Controller or your connections to it. Check the connection diagram (in the wiki) and make sure you've got the proper wires secured in the proper screw terminals, with no loose wire ends connecting to other random spots.
If that's so and the heater goes on anyway, then check the green LED corresponding to that MOSFET on the board. If it's off and the heater is on, then the MOSFET may be shorted and that calls for a new EC...
If that's so and the heater goes on anyway, then check the green LED corresponding to that MOSFET on the board. If it's off and the heater is on, then the MOSFET may be shorted and that calls for a new EC...
kidNeutrino
May 19, 2011, 5:30:50 PM5/19/11
to MakerBot Operators
If the Mosfet is bad, does it rule out a short with the thermocouple?
On May 19, 3:32 pm, Ed Nisley <ed.nis...@gmail.com> wrote:
> Extrusion Heater is on as soon as the ToM powered up
>
> That suggests there's a problem with the MOSFET on the Extruder Controller
> or your connections to it. Check the connection diagram (in the wiki) and
> make sure you've got the proper wires secured in the proper screw terminals,
> with no loose wire ends connecting to other random spots.
>
> If that's so *and* the heater goes on anyway, then check the green LED
On May 19, 3:32 pm, Ed Nisley <ed.nis...@gmail.com> wrote:
> Extrusion Heater is on as soon as the ToM powered up
>
> That suggests there's a problem with the MOSFET on the Extruder Controller
> or your connections to it. Check the connection diagram (in the wiki) and
> make sure you've got the proper wires secured in the proper screw terminals,
> with no loose wire ends connecting to other random spots.
>
> corresponding to that MOSFET on the board. If it's off and the heater is on,
> then the MOSFET may be shorted and *that* calls for a new EC...Ed Nisley
May 19, 2011, 6:23:00 PM5/19/11
to make...@googlegroups.com
If the Mosfet is bad, does it rule out a short with the thermocouple?
All things are possible (except skiing through a revolving door), but I doubt that the thermocouple will be involved in this one: if it was carrying the extruder current, a trace on the Extruder Controller would burn out...
I also doubt that there's anything horrible happening at the Thermal Core, because the resistance readings you're getting seem to be about right: the nominal value is 2.5 ohm and you're seeing 2.8, which is close enough.
The fact that you're getting 1.2 ohm across the thermocouple means that it's intact. You can also check for shorts by measuring the resistance from either thermocouple wire to either extruder heater wire: an open circuit means everything's fine. Measure from both of them to the Thermal Core itself and, again, you should get an open circuit.
Happy hunting!
I also doubt that there's anything horrible happening at the Thermal Core, because the resistance readings you're getting seem to be about right: the nominal value is 2.5 ohm and you're seeing 2.8, which is close enough.
The fact that you're getting 1.2 ohm across the thermocouple means that it's intact. You can also check for shorts by measuring the resistance from either thermocouple wire to either extruder heater wire: an open circuit means everything's fine. Measure from both of them to the Thermal Core itself and, again, you should get an open circuit.
Happy hunting!
kidNeutrino
May 19, 2011, 6:36:08 PM5/19/11
to MakerBot Operators
OK so after reading up on the issue and the helpful advice from Ed
Nisley and B Stott I think I can be more descriptive:
As I said before I get a wonky error with the Extrusion Head and it
heats up at power on. I am triple-sure that all connections to the EC
are in the right polarity.
I think I may have made an accidental electrical connection to the
block when I tightened down the bolt holding the themocouple (not
putting enough Kapton tape to insulate it). The Control Panel was
reading 1023C for the current temp. That suspiciously looks like a
analog signal limit and the ToM didn't spontaneously combust... ;)
If I disconnect the heater wires the head cools but also the temp
reading gives me something believable and it shows a steady drop as it
cools. I can certainly rebuild the head easily enough, but I am _very
worried_ that I may have fried the mosfet from all the reading I have
done today.
I was working on troubleshooting the axis drives on the machine when I
rediscovered the worrisome warnings on the Testing Your Bot page:
"To repeat, NEVER OPERATE THE HEATER if the reported temperature is
anything other than room temperature, usually around 20°C." DOH!
The ToM had been on power for quite some time as I was assisting
others intermittently. I have already suggested that they move this
procedure to the top of that page.
Nisley and B Stott I think I can be more descriptive:
As I said before I get a wonky error with the Extrusion Head and it
heats up at power on. I am triple-sure that all connections to the EC
are in the right polarity.
I think I may have made an accidental electrical connection to the
block when I tightened down the bolt holding the themocouple (not
putting enough Kapton tape to insulate it). The Control Panel was
reading 1023C for the current temp. That suspiciously looks like a
analog signal limit and the ToM didn't spontaneously combust... ;)
If I disconnect the heater wires the head cools but also the temp
reading gives me something believable and it shows a steady drop as it
cools. I can certainly rebuild the head easily enough, but I am _very
worried_ that I may have fried the mosfet from all the reading I have
done today.
I was working on troubleshooting the axis drives on the machine when I
rediscovered the worrisome warnings on the Testing Your Bot page:
"To repeat, NEVER OPERATE THE HEATER if the reported temperature is
anything other than room temperature, usually around 20°C." DOH!
The ToM had been on power for quite some time as I was assisting
others intermittently. I have already suggested that they move this
procedure to the top of that page.
kidNeutrino
May 19, 2011, 6:37:40 PM5/19/11
to MakerBot Operators
Thanks again Ed. Will try those tomorrow morning.
Z LeHericy
May 19, 2011, 10:41:04 PM5/19/11
to make...@googlegroups.com
Sounds to me like you're right about the short to the block, but it would also mean there's a short to the power resistors (unless you're running mk6+...
PS. You can ski through a revolving door: they're all required to fold like this http://www.internationalrevolvingdoors.com/images/WingCollps01.jpg in case of a fire :-)
-Z
Ed Nisley
May 20, 2011, 6:29:07 AM5/20/11
to make...@googlegroups.com
they're all required to fold like this
I'd end up with one ski on each side of that center post...
Robie
May 20, 2011, 8:34:41 AM5/20/11
to MakerBot Operators
That sounds suspiciously like an issue I've been having. In my case I
have traced much of my trouble back to the setting in Toolhead Onboard
Settings getting corrupted. When things get wonky I can usually count
on having very wrong random numbers in the PID as well as the heater
set up.
have traced much of my trouble back to the setting in Toolhead Onboard
Settings getting corrupted. When things get wonky I can usually count
on having very wrong random numbers in the PID as well as the heater
set up.
kidNeutrino
May 22, 2011, 6:49:11 PM5/22/11
to MakerBot Operators
My suspicions appear to be true the thermocouple was shorted to the
block. Now I am getting correct readings and behaivor. Thank you all
for your observations and advice.
-kN
block. Now I am getting correct readings and behaivor. Thank you all
for your observations and advice.
-kN
B Stott
May 22, 2011, 7:05:36 PM5/22/11
to make...@googlegroups.com
So - it is again proof that a short will not blow the whole bot's electronics. But, it will cause strange readings.
Don't forget to do what E.Nisley outlines on his blog and many others attest to (myself included) - electrically ground all.... Sorry, I lost the link and it did not magically appear when I Googled....
I've ground all to the PSU.
Don't forget to do what E.Nisley outlines on his blog and many others attest to (myself included) - electrically ground all.... Sorry, I lost the link and it did not magically appear when I Googled....
I've ground all to the PSU.
Rift
May 22, 2011, 10:06:06 PM5/22/11
to MakerBot Operators
I had something similar happen with my HBP last night. Somehow my
toolhead settings got corrupt and were spitting out all sorts of silly
numbers. But whenever I turned the TOM on the HBP would turn on.
toolhead settings got corrupt and were spitting out all sorts of silly
numbers. But whenever I turned the TOM on the HBP would turn on.
kidNeutrino
May 22, 2011, 10:08:02 PM5/22/11
to MakerBot Operators
Brian Stott
May 22, 2011, 11:20:42 PM5/22/11
to make...@googlegroups.com
Say, a tip on the Thermocouple (TC)attachment.
I drilled a 1/8" ?ish hole about 1/8" ish deep near the TC bolt hole. Then I bent my TC tip (<1/8") 90 degrees, wound Kapton to cover the tip and woven fibergass sheath to extend about 2" beyond the eventually ceramic and taped heater block. I then stuffed the TC tip into the hole. Getting a bigger small washer I captered the TC wire to keep the tip in the hole rather than struggling to keep the slippery tip under the washer. I can now pull the assembly out - move, bend, place and hang it without having the tip squeeze loose.
--
Reply all
Reply to author
Forward
0 new messages