how to troubleshoot when Sanguinololu not heating

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Joined: Wed Jul 01, 2015 12:52 pm

how to troubleshoot when Sanguinololu not heating

Post by Sherry » Fri Oct 30, 2015 11:01 am

1.Extruder/Hotbed is not heating
This is the SCH of extruder & hot bed heater
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Q1 is hot end mosfet,Q2 is hot bed mosfet.
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1. Firstly, let us check power supply outputs. Some people use host power supply whose one of output is 5V which can’t support hotend/hotbed to heat obviously.
QQ图片20151030103013.png (2.2 KiB) Viewed 10828 times
Then checking whether the 12V DC could power up the mainboard or not.
①Only plug USB without 12V DC, the power LED is lighted.
②Only turn on 12V DC without USB. The LED is lighted as well.
If not,The 12V DC is not turn on or broken;
Or L7805 is broken.
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power led.jpg
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2. Secondly, checking if the mainboard temp reading and thermistors are good. Sometimes the LCD is not sensitive, please reset the LCD panel before reading LCD every time.
1) Make the both thermistor slots open circuit. The LCD will display 0/0, 0/0, MIN TEMP.
open circuit.png
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2) Make the both thermistor slots short circuit by plugging jumper caps. The LCD will display 358/0,358/0 , MAXTEMP.
short circuit.png
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3) Plug will display room temperature/0, room temperature/0.
thermistor.png (579.52 KiB) Viewed 10828 times
3. Thirdly, let us check whether the resistance of hot bed and hot end are normal.
Tip:Please short out the red and black probe at first, you can read a internal resistance. To get a more accurate resistance. The internal resistance should be subtracted from the resistance you measure next.
internal resistance.png
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Hot end: it’s resistance is 3.8ohms. 3.8 minus 0.3 is 3.5ohms.
Tip: please let probe tips touch metal carbonyl conducting layer inside insulation material.
hot end resistance.jpg
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Hot bed: it’s resistance is 1-2ohms.
Here is two type of hot bed: MK2A&MK2B
hot bed(MK2A).png
hot bed(MK2A).png (610.39 KiB) Viewed 10827 times
hot bed(MK2B).png
hot bed(MK2B).png (830.33 KiB) Viewed 10827 times
4. Finally, let us check their MOSFETS.
Please plug both hot end heating wire and hot bed’s.
Tip: Make the metal carbonyl conducting layer of heat cables be in good contact with slots. Otherwise the following test will be fail.
MOSFETS.png (290.05 KiB) Viewed 10827 times
When not heating
hot bed mosfet(no heating).jpg
hot bed mosfet(no heating).jpg (130.27 KiB) Viewed 10827 times
When heating, MOSFET are breakover.
hot end mosfet.jpg
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hot bed mosfet.png
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Extruder is overheat
1. Checking if the outputs of power supply are over 12V.
2. Checking if mainboard can read correct temperature and the both thermistor are good.
3. Maybe MOSFET is out of control. In other words, the MOSFET is always on even if it reach the temperature you have set.
In this case, please check if there is short circuit in mainboard.
over heat.jpg
over heat.jpg (168.02 KiB) Viewed 9013 times

Posts: 1
Joined: Wed Jan 16, 2019 7:59 pm

Re: how to troubleshoot when Sanguinololu not heating

Post by soniyasheelu7738 » Wed Jan 16, 2019 8:08 pm

That's a definitely bad, as this will short the output from the transistors, it shouldn't damage them though.

It is possible to get insulation washers, to put between the transistors and the hotend, but the easy solution is to just detach the hotend transistor from the heatsink (it shouldnt really get hot), and make sure it doesn't touch the heatsink. Use some tape, to isolate it.

But you really should isolate the transistor from the heatsink, to minimize the risk for shorting the output.

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Re: how to troubleshoot when Sanguinololu not heating

Post by William » Wed Jan 16, 2019 11:42 pm

Your point is correct and clear!
-Keep your mind and try to test it. :)
-Everything will be fun!-Support all Getech printer.
-You can ask me the questions and I will kindly reply.
-Respect others is the best way you can get help!

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Joined: Tue Jan 29, 2019 5:30 am

Re: how to troubleshoot when Sanguinololu not heating

Post by hakkubaba » Tue Jan 29, 2019 5:34 am

I am an electrical engineer and thats a complicated problem that you have it is looking worst from my point of view for your system. Make the help of epople who you thing a trend expert in the meidum to undo some things that will make it ease for the people who are going to face it.

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