Geeetech

Hello,

I have minimally used this printer due to problems with the x-axis jumping around. I have been able to print some small pieces. But now, both of my fans have stopped working. This means the board fan and the extruder fan.

It seems it happened in the middle of a print. I have tried manually setting the speed on the PWM fan to 255, and nothing.

I did some measurements:

Open voltage: 8.9V
Voltage with fan connected: 3.2V

The fans work fine when I hook up a battery to them, so they are Ok.

I looked at the board and nothing seems burnt out. The bed and the extruders heat up normally. The 3rd MOSFET, the one closer to the center of board, heats up quite a bit when the bed is heating.

Any ideas?

The voltage on common "FAN" connector should be 12V,and only the fan connected to "PWM_fan" socket could be controlled.

The voltage on common "FAN" connector should be 12V,and only the fan connected to "PWM_fan" socket could be controlled.

Yes, I know.

But neither fan is giving out more than 9V on open circuit and 3V when hooked up to a load. So there is something wrong. I am trying to figure out if it is the board or the power supply.

If you have any other ideas please let me know so I can figure out how to fix it.

Thank you Bang.

Did you fix it?
And did you test if your DC output was normal?

I have not fixed it. But I did test the power-supply and it is providing 12V properly. This is not surprising since only the fans went out, while the motors and heating elements work perfectly.

Is there a schematic of the GT2560 board? My guess is that a power transistor failed or something like that.

I have one of the early boards (it even seems to have an extra resistor soldered directly between two components, not surface mounted on the PCB... probably fixing an error with the design).