hotbed/extruder is not heated up(GT2560/GTM32/sanguinololu)

[Mark]

If your board is sanguinololu, check out this link:
http://www.geeetech.com/forum/viewtopic ... 13&t=17117

If your hotbed or extruder is not heated up(GT2560/GTM32), please refer to the informations below to check it:

1. Check the temperature first
If it shows “room temperature/0, room temperature/0”,Both extruder thermistor and hot bed thermistor are good. If either or none of them is room temperature, then the thermistor is bad contact. If one of them is good, you can swap them to see if the other one is dead or not.
2 Check the board is working or not
2.1 Check the board power
With the board powered on, the lower left LED lights will light up. If not, then check the fuse on the board. You can measure the voltage of the two sides of the fuse, if there is a big difference then the fuse is dead.
For GT2560, board power usually is 12V, and 5V for the mainchip.

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For GTM32 on M201, main power is 24V and 3.3V for mianchip.

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2.2 Check the mosfet
Manually heat up the hotbed and extruders, if the LED lights under the hotbed and extruder slots all lighted up, then the mosfet that controls the heating is good.

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If not, the mosfet might be dead. You can check the mosfet as follows:
For GT2560, use the multimeter to measure the voltage between pin 2 and pin 3 of the mosfet, when heated up it is 0V,and when not it is 12V.

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The type of fuse and mosfet are as follows:
name specific type parameter
fuse SMT 5*10 0154010.DRT 10A/125V
fuse SMT 5*10 0154015.DRT 15A/125V
mosfet TO-220 STP55NF06LTO 　

For GTM32, measure the voltage between the pin1 and any of the other pins(GND), when heated up it is 0V and when not it is 24V.

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2.3 Check the resistance of the heating cartridge and hotbed
Measure the resistance of the heating cartridge and hotbed.
For GT2560:
The resistance of the hotbed ranges from 1-2ohms. When shorted out it is less than 1ohms and when open circuit it is infinite.
The resistance of the heating cartridge is about 3.6ohms. Also when shorted out it is less than 2ohms and when open circuit it is infinite. If there is a short circuit or open circuit, check the wiring or the component itself. You can also use a good one to verify it. Measure the resistance as follows.

Note: For GTM32, cause the mainpower is 24V, so the resistance of the heatbed should be about 5ohms and 12.1ohms for the heating cartridge.

Measure the resistance of heater.
1)unplug heating wire from mainboard.
2)turn the multimeter to Ω.
3)put the red probe of multimeter on one end of heating wire ,put black probe on another end.please let probe tips touch metal carbonyl conducting layer inside insulation material.

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Measure the resistance of hotbed.

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3. When heating up the hotbed, the temp cannot reach 85℃ or it takes a long time to reach 100℃
Generally, the hotbed can be heated up to 70 ℃ in about 2-3mins, and it takes about 40mins to reach to the preset temperature. This is because compared to hotend, the hot bed area is too big and dissipates quickly, while a fan or air conditioner will also enhance the heat dissipation. The role of the hot bed is to keep the printings from bending. If you use ABS, with a temperature of 75-85 degrees and use some sprays on the hotbed, you’ll also get it work.

[ADVALL]

The cold resistance of the 12 V bed should be between 1.00 and 1.20 ohms (NOT 1-2 Ohms) beds with higher ohms are not to specification and will not heat to 110 deg or take a long time with a required overhead 120 deg Max.

To get a accurate measure of resistance of the bed's element both Voltage and Current readings should be taken across the element directly and at the same time using two meters whilst the element temperature is low as resistance rises (ie current falls) with increasing temperature.

A simple multimeter direct reading will be low for such a low ohms components as this.

For easy handling of ABS filament a watts rating of at room temperature 120 is required.

[Yinosization]

Hello mark,

When i mesured my resistance of the heater i haven't 3.8 ohm, but an OL mesure. My hotend is defect ?

[sambam1973]

I have the issue and it seems to be the mosfet.

Can someone confirm that this is the correct replacement please?

http://uk.rs-online.com/web/p/products/ ... oCc07w_wcB

It is the mosfet TO-220 STP55NF06L (without the 'TO' at the end). My knowledge of electronics is not sufficient for me to make the decision.

Much appreciated.

Neil

[comppoly3d]

Hi, thanks for this thread, it's been a great help, but my heatbed for the i3 pro b stop working after no problems for the first month. I noticed that the LED light for the heatbed on the control board doesn't turn on anymore. I checked the heatbed itself at the hotend-in and it works fine. The fuses for the heatbed and hotend also seem to be fine bcause I switched them with each other. Also the control board in for the heatbed gives about 11.7 volts and the red LED lights up when the heatbed is unplugged. As soon as I plug in the heatbed or hotend ( I checked with both) is plugged in the red LED turns of and the control board seems to stop giving power to the user. Do you have a solution idea for the problem? I thought about reprogramming the control board so that I can use the free input for the second hotend as the heatbed input, would that be possible? Alternatively I would like to check the MOSFET by replacing the MOSFET for the second hotend with the heatbed MOSFET. Any ideas about that? Greetings

[William]

Hi,
I think you can replace the heatbed MOSFET with the MOSFET for the second hotend.

[comppoly3d]

thanks for your help, I found the source of the problem: one of the power supply cables burned right at the control board power input, but the board itself seems to be fine, just the input is a total mess on the inside. I wonder about what caused this problem, i guess a manufacturing error or a power oversupply...
I am thinking about removing the plastic covers of the input in order to solder the cables directly to the input pins. Any suggestions?

[William]

thanks for your help, I found the source of the problem: one of the power supply cables burned right at the control board power input, but the board itself seems to be fine, just the input is a total mess on the inside. I wonder about what caused this problem, i guess a manufacturing error or a power oversupply...
I am thinking about removing the plastic covers of the input in order to solder the cables directly to the input pins. Any suggestions?

Sure,you can solder it,but watch out the electrodes.
As for the reason,maybe its a overloading.You can check as the post shows to see if there are some problems on components.

[comppoly3d]

I checked again and noticed that a component on the chip is damaged (see pic).I checked the gt2560 circuit diagram, but couldn´t find anything labeled Q4. Might be a circuit breaker? Any idea´s? Also i don´t know if this component cuaused the overload or the overload caused this thing to fail... Anyway, if anybody knows what kind of component this is and if it´s fixable, I will be thankfull for any help. Meanwhile i think I better order a new gt2560

[comppoly3d]

here is a link to the pic´s of the burned input and component:

https://www.dropbox.com/s/k1sol39b21lx9 ... 4.jpg?dl=0

https://www.dropbox.com/s/hw7w532n0924e ... 8.jpg?dl=0