SOLVED: Still PWM Fan problems on GT2560 V3.0?

[Chris81]

Hi all,

sorry for beeing a newby on 3D Printing, many things to learn about.... Got my A10 with GT2560 V3.0 Board and after printing some more or less nice "dogs" (and some other stuff) i realized that the fan on the hot end cannot be controlled. I did some prints where the fan is set to 0% at the beginning and then goes up to 80% while printing. On the LCD both settings are displayed, but the fan is at 100% all the time.

I already read some topics about replacing a MOSFET (Q5 for example), but these topics are always about older GT2560 boards. Does anyone have some experience with the Version 3.0 and fan problems? On my board only E0 is in use. The only 3-Pin MOSFET on E0 is Q2, which looks okay. It´s difficult to reach with soldering iron, so i would prefer "other ways" before i will start soldering. Is there any documentation on the pinout? I already spent some ours of searching the forum without success.

Thank you
Chris

[axiom]

http://www.geeetech.com/forum/viewtopic ... 98&t=61646

Check out the link in the first post.

[Chris81]

Thank you for the link. I tried to modify the firmware as mentioned, but it didn´t solve the problem. The fan is getting 24V all the time, no matter which configuration is active. And i also tried different settings on the LCD->Temp->Fan Speed from 0-255. No change here.

[Chris81]

By the way: Is it possible that there is a mistake in the GT2560 V3.0 schematic, "Fan Connectors" section? Parts like Q5, R15, R20 are all belonging to E0 in the schematic, on my board they are placed in the E2 area.

[Chris81]

Made some more measurements on the board. PWM-Output is working. Transistor Input (Q2) is 0V at Fan=0 and 5V at Fan=255 (and of course ~3V in the middle position). But the fan voltage stays 24V all the time. So Q2 seems to be damaged. Will come back when i got a spare part.

[Chris81]

Problem nearly solved:
I changed the Q2 from AP2306AGN to a new one (IRLML6344TRPBF) without success. Fan is still running on 100%.

I measured all cables from GT2560board to the hot end incl. the Geeetech extruder Extension Board. I found a short circuit from the left "air blower" connector of the expansion board to GND caused by switched cables on the GT2560 H6! This forces Q2s drain to GND all the time, which leads to 100% fan (air blower) all the time. I switched the blue and black cable of H6 on the GT2560 and now the fan goes down to around 50% when fan is set to FanSpeed=0. Not satisfying, but i´m getting more and more to a normal fan behavior.

Next step: I disconnected H6 (something to do with 3DTouch, Pin PC7 of the Mega2560) and now the air blower fan is behaving normal (FanSpeed=0 => no rotation, FanSpeed=0 => 100% rotation). I will go on searching the problem. Because one day i want to switch to autoleveling via 3DTouch and i have to connect H6 again.

Doas anyone know what Z_Min (Pin PC7) in the schematic is used for? Maybe it´s a kind of firmware problem. I´m using Marlin 1.1.8 without 3DTouch.

[Chris81]

I am in contact with geetech. They suggest a replacement board which did not arrived yet. As i went on printing without the H6 connector i also bought a 3DTouch sensor. When i connect the black/white cable to the extruder pcb board, my fan problems came back again . H6 is still disconnected from the GT2560V3.

Still searching for short circuit on the extruder pcb or cabling....

[Chris81]

Because there came no solution from geeetech i went on measuring the wiring from GT2560 to the extruder PCB board. I found a short circuit on the CON2X6 connector (Pin 3 and 5) of the extruder PCB board, caused by a unclean solder joint (solder leftovers) at the CON2X6 connector . I disassembled the extruder pcb and cleaned evereything up. Now everything is fine. Seems like there is bit more quality control needed.....