Fans slow down when extruder or hotbed activated

[JustinSB]

Are both fans supposed to noticeably slow down when either the hotbed or the hotend are turned on & warming up? If I turn the hotend off, I can hear them instantly speed up too...?

It's really quite noticeable, & makes me wonder about my PSU? Is this normal?

[William]

The speed of the fan up to max and when the printer power on?

[_kaktus_]

I will say this:
a similar effect I once noticed in my model.
For me, this is due to a shortcoming in the design phase.
A small linear stabilizer must work hard. The result is its overheating.
Therefore, the element begins to limit its output power to prevent burning.

I will soon finish the new description: kaktus' guide - fans - appendix

It will be clearly exposed there what I am talking about now.
You have a different printer model (whose design I do not know), but I think the problem may have remained.
Wait patiently ;-)
I will present a simple solution. (workaround).

for me it is not a mistake but a simple oversight because of the lack of proper tests.
I warmly greet the entire Geeetech team. ;-D

[_kaktus_]

Now I can advise you
Do not turn on all fans if it is not necessary. And if it is, turn it on for a short time.

[JohnDeere630]

Sounds like a weak power supply. I had the replace the PS on my I3 right off the bat; it only put out 8 volts.

[JustinSB]

I only have the stock motherboard fan on my Pro W, along with the 30mm fan on my E3D Lite6 hotend, as the E3D Titan extruder doesn't have a fan. They are both TWO wire fans, ie there's no speed controller, they are either full on, or off, & I can't work out how to turn them off.

I can't get them to stop when not in use in the firmware, as I just can't figure what settings to change in Marlin 1.1.7 stable Configuration_adv.h - I looked up the pins in pins_GT2560_REV_A_PLUS.h and pins_GT2560_REV_A.h where it said:

//
// Heaters / Fans
//
#define HEATER_0_PIN 2 // I assume this is Hotend 0
#define HEATER_1_PIN 3 // I assume this is Hotend 1 (unused)
#define HEATER_BED_PIN 4 // I assume this is Hotbed
#define FAN_PIN 7 // I assume this is the PWM that I should use for my part cooling fan, when I get one

so, in Configuration_adv.h, I changed this section to use the Hotend 0 pin

#define E0_AUTO_FAN_PIN 2 // (was originally -1)

But alas, it did nothing. Do you know what I did wrong?

[JohnDeere630]

Pin 2 is a PWM pin on the chip. If your 2-pin fan connectors are connected to VCC and GND, they will be on when the motherboard is powered on, irrespective of the firmware settings. A fan draws too much to be powered by an I/O pin from the microprocessor, which tops out at 40 milliamps. It seems that a 3-wire fan may solve your issue.

[JustinSB]

Ah, sorry, I just found

https://www.geeetech.com/forum/viewtopi ... 821#p82779

and

https://www.geeetech.com/forum/viewtopi ... 38&p=82880

which have all of your notes on this. Thanks.

[JustinSB]

William,

on the GT2560 Rev A+ board, it has Fan1, Fan2 & Fan3, along with a PWM port that is generally used for a part cooling fan. All of Fan ports have 3 connector pins, although both of the Geeetech fans that are plugged into them only have the two power cables (that's the hotend fan & the circuit board cooling fan). They all have a control pin though.

Do you know what the pin numbers for each fan are so I can use them in Marlin?

[William]

William,

on the GT2560 Rev A+ board, it has Fan1, Fan2 & Fan3, along with a PWM port that is generally used for a part cooling fan. All of Fan ports have 3 connector pins, although both of the Geeetech fans that are plugged into them only have the two power cables (that's the hotend fan & the circuit board cooling fan). They all have a control pin though.

Do you know what the pin numbers for each fan are so I can use them in Marlin?

The pin number of PWM fan is "7"
Others fan interface are no define