Reprap Forum - RAMPS Electronics

Re: Anet A8+ resurrection - Ramps1.6 on Mega2560

ctroyer26 — Tue, 28 Apr 2026 09:14:45 -0400

Thanks much.
That's exactly the clarification I needed. I have already purchased the new mosfets for 5V input to control the 24V circuits, so I'll stick with that approach for now.
I'll post results as I get them.
Thanks, C.

Re: Anet A8+ resurrection - Ramps1.6 on Mega2560

Dust — Sun, 26 Apr 2026 22:11:48 -0400

Note: Most people use a mosfet on the current mosfet

ie you plug a mosfet into the bed connector, the mosfet gets 12v and switchess the 24v so you don't need to make any firmware changes

But to answer your question.

These defines are used for RAMPS

#ifndef MOSFET_A_PIN
  #define MOSFET_A_PIN                        10
#endif
#ifndef MOSFET_B_PIN
  #define MOSFET_B_PIN                         9
#endif
#ifndef MOSFET_C_PIN
  #define MOSFET_C_PIN                         8
#endif

They get rearranged depending on what motherboard you select
For BOARD_RAMPS_14_EFB it says you need a mosfet for the extruder, fan and bed
default being

    #define HEATER_0_PIN               MOSFET_A_PIN
    #define HEATER_BED_PIN          MOSFET_C_PIN
    #define FAN0_PIN                        MOSFET_B_PIN

All of these are in "#ifndef" blocks so you can over ride them in Configuration.h by simply adding

#define HEATER_0_PIN {logical pin number you want to use}
#define HEATER_BED_PIN {logical pin number you want to use}

The Marlin/src/pins/ramps/pins_RAMPS.h file contains documentation on all connectors

//
// AUX1    5V  GND D1  D0
//          2   4   6   8
//          1   3   5   7
//         5V  GND A3  A4
//
#define AUX1_05                               57  // (A3)
#define AUX1_06                                1  // TX0
#define AUX1_07                               58  // (A4)
#define AUX1_08                                0  // RX0

//
// AUX2    GND A9 D40 D42 A11
//          2   4   6   8  10
//          1   3   5   7   9
//         VCC A5 A10 D44 A12
//
#define AUX2_03                               59  // (A5)
#define AUX2_04                               63  // (A9)
#define AUX2_05                               64  // (A10)
#define AUX2_06                               40
#define AUX2_07                               44
#define AUX2_08                               42
#define AUX2_09                               66  // (A12)
#define AUX2_10                               65  // (A11)

Pins 55 and 56 are not on aux2 and are used as follows.

#define X_DIR_PIN                             55  // (A1)
#define Y_ENABLE_PIN                     56  // (A2)

Changing pins

You noticed how some pins are A and others D, D is digital and all pins can do this, A is analog in, only pins with a A prefix can do analog in
In code you just use the number, you want the digital function you use the digital pin number.

Eg if you add this to you configuration.h

#define HEATER_0_PIN 57
#define HEATER_BED_PIN 58

the hotend with use pin 57 to control its heater
and the heated bed will use pin 58

alternatively you could set

#define MOSFET_A_PIN 57
#define MOSFET_C_PIN 58

The result is the same

Note these pins are not physical pins numbers as on the chip. they are Mapped logical pin numbers as defined by arduino

**Arduino Mega 2560 PIN mapping table**

| Pin Number | Pin Name                 | Mapped Pin Name                |
| ---------- | ------------------------ | ------------------------------ |
| 1          | PG5 ( OC0B )             | Digital pin 4 (PWM)            |
| 2          | PE0 ( RXD0/PCINT8 )      | Digital pin 0 (RX0)            |
| 3          | PE1 ( TXD0 )             | Digital pin 1 (TX0)            |
| 4          | PE2 ( XCK0/AIN0 )        |                                |
| 5          | PE3 ( OC3A/AIN1 )        | Digital pin 5 (PWM)            |
| 6          | PE4 ( OC3B/INT4 )        | Digital pin 2 (PWM)            |
| 7          | PE5 ( OC3C/INT5 )        | Digital pin 3 (PWM)            |
| 8          | PE6 ( T3/INT6 )          |                                |
| 9          | PE7 ( CLKO/ICP3/INT7 )   |                                |
| 10         | VCC                      | VCC                            |
| 11         | GND                      | GND                            |
| 12         | PH0 ( RXD2 )             | Digital pin 17 (RX2)           |
| 13         | PH1 ( TXD2 )             | Digital pin 16 (TX2)           |
| 14         | PH2 ( XCK2 )             |                                |
| 15         | PH3 ( OC4A )             | Digital pin 6 (PWM)            |
| 16         | PH4 ( OC4B )             | Digital pin 7 (PWM)            |
| 17         | PH5 ( OC4C )             | Digital pin 8 (PWM)            |
| 18         | PH6 ( OC2B )             | Digital pin 9 (PWM)            |
| 19         | PB0 ( SS/PCINT0 )        | Digital pin 53 (SS)            |
| 20         | PB1 ( SCK/PCINT1 )       | Digital pin 52 (SCK)           |
| 21         | PB2 ( MOSI/PCINT2 )      | Digital pin 51 (MOSI)          |
| 22         | PB3 ( MISO/PCINT3 )      | Digital pin 50 (MISO)          |
| 23         | PB4 ( OC2A/PCINT4 )      | Digital pin 10 (PWM)           |
| 24         | PB5 ( OC1A/PCINT5 )      | Digital pin 11 (PWM)           |
| 25         | PB6 ( OC1B/PCINT6 )      | Digital pin 12 (PWM)           |
| 26         | PB7 ( OC0A/OC1C/PCINT7 ) | Digital pin 13 (PWM)           |
| 27         | PH7 ( T4 )               |                                |
| 28         | PG3 ( TOSC2 )            |                                |
| 29         | PG4 ( TOSC1 )            |                                |
| 30         | RESET                    | RESET                          |
| 31         | VCC                      | VCC                            |
| 32         | GND                      | GND                            |
| 33         | XTAL2                    | XTAL2                          |
| 34         | XTAL1                    | XTAL1                          |
| 35         | PL0 ( ICP4 )             | Digital pin 49                 |
| 36         | PL1 ( ICP5 )             | Digital pin 48                 |
| 37         | PL2 ( T5 )               | Digital pin 47                 |
| 38         | PL3 ( OC5A )             | Digital pin 46 (PWM)           |
| 39         | PL4 ( OC5B )             | Digital pin 45 (PWM)           |
| 40         | PL5 ( OC5C )             | Digital pin 44 (PWM)           |
| 41         | PL6                      | Digital pin 43                 |
| 42         | PL7                      | Digital pin 42                 |
| 43         | PD0 ( SCL/INT0 )         | Digital pin 21 (SCL)           |
| 44         | PD1 ( SDA/INT1 )         | Digital pin 20 (SDA)           |
| 45         | PD2 ( RXDI/INT2 )        | Digital pin 19 (RX1)           |
| 46         | PD3 ( TXD1/INT3 )        | Digital pin 18 (TX1)           |
| 47         | PD4 ( ICP1 )             |                                |
| 48         | PD5 ( XCK1 )             |                                |
| 49         | PD6 ( T1 )               |                                |
| 50         | PD7 ( T0 )               | Digital pin 38                 |
| 51         | PG0 ( WR )               | Digital pin 41                 |
| 52         | PG1 ( RD )               | Digital pin 40                 |
| 53         | PC0 ( A8 )               | Digital pin 37                 |
| 54         | PC1 ( A9 )               | Digital pin 36                 |
| 55         | PC2 ( A10 )              | Digital pin 35                 |
| 56         | PC3 ( A11 )              | Digital pin 34                 |
| 57         | PC4 ( A12 )              | Digital pin 33                 |
| 58         | PC5 ( A13 )              | Digital pin 32                 |
| 59         | PC6 ( A14 )              | Digital pin 31                 |
| 60         | PC7 ( A15 )              | Digital pin 30                 |
| 61         | VCC                      | VCC                            |
| 62         | GND                      | GND                            |
| 63         | PJ0 ( RXD3/PCINT9 )      | Digital pin 15 (RX3)           |
| 64         | PJ1 ( TXD3/PCINT10 )     | Digital pin 14 (TX3)           |
| 65         | PJ2 ( XCK3/PCINT11 )     |                                |
| 66         | PJ3 ( PCINT12 )          |                                |
| 67         | PJ4 ( PCINT13 )          |                                |
| 68         | PJ5 ( PCINT14 )          |                                |
| 69         | PJ6 ( PCINT 15 )         |                                |
| 70         | PG2 ( ALE )              | Digital pin 39                 |
| 71         | PA7 ( AD7 )              | Digital pin 29                 |
| 72         | PA6 ( AD6 )              | Digital pin 28                 |
| 73         | PA5 ( AD5 )              | Digital pin 27                 |
| 74         | PA4 ( AD4 )              | Digital pin 26                 |
| 75         | PA3 ( AD3 )              | Digital pin 25                 |
| 76         | PA2 ( AD2 )              | Digital pin 24                 |
| 77         | PA1 ( AD1 )              | Digital pin 23                 |
| 78         | PA0 ( AD0 )              | Digital pin 22                 |
| 79         | PJ7                      |                                |
| 80         | VCC                      | VCC                            |
| 81         | GND                      | GND                            |
| 82         | PK7 ( ADC15/PCINT23 )    | Analog pin 15 / Digital pin 69 |
| 83         | PK6 ( ADC14/PCINT22 )    | Analog pin 14 / Digital pin 68 |
| 84         | PK5 ( ADC13/PCINT21 )    | Analog pin 13 / Digital pin 67 |
| 85         | PK4 ( ADC12/PCINT20 )    | Analog pin 12 / Digital pin 66 |
| 86         | PK3 ( ADC11/PCINT19 )    | Analog pin 11 / Digital pin 65 |
| 87         | PK2 ( ADC10/PCINT18 )    | Analog pin 10 / Digital pin 64 |
| 88         | PK1 ( ADC9/PCINT17 )     | Analog pin 9  / Digital pin 63 |
| 89         | PK0 ( ADC8/PCINT16 )     | Analog pin 8  / Digital pin 62 |
| 90         | PF7 ( ADC7/TDI )         | Analog pin 7  / Digital pin 61 |
| 91         | PF6 ( ADC6/TDO )         | Analog pin 6  / Digital pin 60 |
| 92         | PF5 ( ADC5/TMS )         | Analog pin 5  / Digital pin 59 |
| 93         | PF4 ( ADC4/TCK )         | Analog pin 4  / Digital pin 58 |
| 94         | PF3 ( ADC3 )             | Analog pin 3  / Digital pin 57 |
| 95         | PF2 ( ADC2 )             | Analog pin 2  / Digital pin 56 |
| 96         | PF1 ( ADC1 )             | Analog pin 1  / Digital pin 55 |
| 97         | PF0 ( ADC0 )             | Analog pin 0  / Digital pin 54 |
| 98         | AREF                     | Analog Reference               |
| 99         | GND                      | GND                            |
| 100        | AVCC                     | VCC                            |

Anet A8+ resurrection - Ramps1.6 on Mega2560

ctroyer26 — Sun, 26 Apr 2026 09:50:38 -0400

All,
I am repairing/upgrading my antique Anet A8Plus. I burned out the extruder motor driver on the original Anet board by pulling jammed TPU filament out of the hot end. That generated enough voltage and current to fry the poor motor controller. As the original Anet board uses surface mount components, I opted to upgrade to the Ramps 1.6, with individual A4988 motor controllers. I realized too late that the original Anet A8+ uses 24V for the extruder and bed heaters, and set up a new 12V power supply for the mega2560 and Ramps.
At this point, everything is wired, adjusted and working, and it is time to get the heaters working. My plan is to use the Ramps1.6 AUX1 and AUX2 outputs to control external mosfets that will switch the 24V power for those two heating circuits. I have not been able to find clear instruction as to how to name the outputs in the pins_RAMPS.h. According to one schematic, they are labelled A3,D57 and A4,D58 (for AUX1) and A11,D55, A12,D56 (for AUX2). I'm assuming that the A and D differentiate between using these as analog or digital outputs.
Unless someone can tell me different, I guess I'll just make those changes in the pins file, recompile, upload and see what the oscilloscope shows when I send a command to heat the bed or the extruder.
Cheers and thanks, C.

Re: MKS gen2Z v1.1 Marlin configuration SOLUTION

maxr — Thu, 22 May 2025 11:11:22 -0400

Hello I have a solution! The Author of this post is probably not looking for the solution anymore but who ever is reading this most likely still is.

The MKS 2Z boards are named "2Z" because the Z1 and Z2 are hardwired to the same Z stepper signal. So basically where other RAMPS boards would have had a E1 axis is just a second pinout to the same exact signal as on the Z1.

The solution to changing to a dual Y-axis you ask? I found two:

Solution 1 (both Y-axis will have the same signal)
In the pins_RAMPS.h file of marlin change the variable names (or pins) between Z and Y. This will then change your mirrored Z1 and Z2 port into Y1 and Y2 and the Y port will be your new Z

#define Z_STEP_PIN 60
#define Z_DIR_PIN 61
#define Z_ENABLE_PIN 56
#define Z_CS_PIN 49

#define Y_STEP_PIN 46
#define Y_DIR_PIN 48
#define Y_ENABLE_PIN 62
#define Y_CS_PIN 40

Solution 2 (this will let you control the Y axis individually and put Y2 on the extruder port)
Change the pins for E1 to E0 and vice versa. As the 2Z boards only has 4 individual stepper outputs this will remove the possibility to have an extruder but for a CNC you don't need one.
Your E0 port will now be Y2 after commenting and uncommenting the corresponding lines in the configuration_adv.h file

pins_RAMPS.h code to change to:

#define E1_STEP_PIN 26
#define E1_DIR_PIN 28
#define E1_ENABLE_PIN 24
#define E1_CS_PIN 42

#define E0_STEP_PIN 36
#define E0_DIR_PIN 34
#define E0_ENABLE_PIN 30
#define E0_CS_PIN 44

configuration_adv.h code to change to:

#define Y_DUAL_STEPPER_DRIVERS
#if ENABLED(Y_DUAL_STEPPER_DRIVERS)
// Set true if the two Y motors need to rotate in opposite directions
#define INVERT_Y2_VS_Y_DIR true
#endif

As I'm old school and of no interest in any other garbage like sensors and or end stops I made a modified version of marlin 1.1.6 with all of the 3D printer settings removed from the UI and only a move axis, set 0,0,0 and start machining operation from SD card.

well... it does have some tuning features like speed acc jerk and steps per mm still but those come in handy.

Ramps 1.4 > 1.6 "No data"

marc.r — Sun, 19 Jan 2025 12:53:40 -0500

Hello
On a printer I just changed the ramps 1.4 > 1.6 under marlin 1.8.
Everything works fine except the card which is well inserted but message "no data" (tested with 2 displays).
SD card ok and tested with several SD cards.
I suspect a change to be made in the marlin conf files.
Any idea?
Thanks.

Re: Ramps 1.4 fuses

RobinBonl — Sun, 01 Dec 2024 08:06:10 -0500

Thank you for your response (aswell on the other topic).

I'm planning on only using the board to drive stepper motors for a robot arm I'm designing.

Re: Ramps 1.4 fuses

Dust — Sun, 01 Dec 2024 08:01:11 -0500

The 5A power in provides power to:
fans
hotends
vin (atmega2560 power supply)
and stepper motors

If you remove D1 then the mega is safe from getting to much voltage.
but what of the fans or the hotend?

You don't have to replace the 11A fuse if your not putting any power into that circuit.

You may want to take look at [reprap.org]

Ramps 1.4 fuses

RobinBonl — Sat, 30 Nov 2024 14:31:09 -0500

Dear all,

I want power a Ranps 1.4 board with 24V. I read that I have to remove the D1 diode, check all capacitor ratings and replace the fuses.

In my case, I only want to drive the stepper motor's with the ramps board (no heating bed). I saw there was a 30V fuse connected to the 5A line and a 16V connected to the 11A line. If I were to remove the D1 diode and only use the stepper motor 5A power line, can I then just leave the fuses that are already on the board?
Or is it still recommended to replace the fuses?

Greetings, Robin

Re: Wrong Axis is moving:(

Dust — Thu, 19 Sep 2024 18:22:47 -0400

[attachment 121118 Screenshotfrom2024-09-2010-22-10.png]

Re: Wrong Axis is moving:(

Roberts_Clif — Thu, 19 Sep 2024 12:30:19 -0400

Using the basic Marlin, Marlin 2 is a little different but similar

You can look at the pin numbers in
pins_RAMPS.h

Using Arduino IDE

//
// Steppers
//
#define X_STEP_PIN         54
#define X_DIR_PIN          55
#define X_ENABLE_PIN       38
#ifndef X_CS_PIN
  #define X_CS_PIN         53
#endif

#define Y_STEP_PIN         60
#define Y_DIR_PIN          61
#define Y_ENABLE_PIN       56
#ifndef Y_CS_PIN
  #define Y_CS_PIN         49
#endif

#define Z_STEP_PIN         46
#define Z_DIR_PIN          48
#define Z_ENABLE_PIN       62
#ifndef Z_CS_PIN
  #define Z_CS_PIN         40
#endif

#define E0_STEP_PIN        26
#define E0_DIR_PIN         28
#define E0_ENABLE_PIN      24
#ifndef E0_CS_PIN
  #define E0_CS_PIN        42
#endif

#define E1_STEP_PIN        36
#define E1_DIR_PIN         34
#define E1_ENABLE_PIN      30
#ifndef E1_CS_PIN
  #define E1_CS_PIN        44
#endif

/**

I then swapped E0 to E1 pin numbers because my E0 driver died did not have current funds to purchase another.
And wanted to see if it would work. It did.

Re: Wrong Axis is moving:(

paul_schenker — Thu, 19 Sep 2024 09:59:33 -0400

But to define the pins I need to know their numbers and I can`t find them.
Right ? :(
And I don´t know their number.

so wat should I do.

Re: Wrong Axis is moving:(

Dust — Tue, 17 Sep 2024 23:19:15 -0400

The 2B, 2A, 1A 1B four pin ports are the output of the stepper drivers. This has nothing to do with board pins.

The board pins are well documented

[reprap.org] Top left

Re: Wrong Axis is moving:(

paul_schenker — Tue, 17 Sep 2024 15:18:12 -0400

Everything is plugged in correctly, but I'm a bit stuck on how to define the port. ecause there are multiple 2A, 2B, etc. So I can't define them like that, and I can't find the raw number of those.

does anny boddy know something about that
thanks for the answer paul anton schenker

Re: Problem with output D10

Roberts_Clif — Sat, 14 Sep 2024 12:34:43 -0400

Thank you Dust did remember that one.

Re: Problem with output D10

Dust — Sat, 14 Sep 2024 11:24:14 -0400

Also the mosfet switches gnd. If there is another path to gnd it will stay on

I have seen this many time where the hotend heater cartage is not insulated so the heater block is now at 12v all the time, Current doesn't flow due to not having a gnd path. Then the thermistor is screwed to the heater block, if you break the insulation on the leg it forms a gnd connection. Now the hotend is always on.

To test this unplug the thermistor form the controller and turn on the controller. If the hotend now stops heating, that is your issue. (Printer may error and beep at you due to unplugged thermistor)

Note this is actually lucky, if you pinched the other thermistor leg you send 12v into the ADC and kill the pin (or the entire 2560 chip)

Re: Problem with output D10

Roberts_Clif — Sat, 14 Sep 2024 10:56:10 -0400

Do not know if this will help, though I had a problems similar this this.
With the power turned off and the heat bead disconnected measure the resistance from the positive voltage to the hotbed heater if the resistance is very low or zero then you have a short somewhere.

I have purchased many different circuit boards where a solder blob was the problem, have also had traces that do not make the trip from point a to point b without an open trace.

Example this one was an open trace. Have had others where the two traces are connected together shorting trace to power.
[attachment 121106 Trace.jpg]

Searching the logic of the Marlin Code I found this line of code

#define HEATER_BED_INVERTING true

Re: Problem with output D10

nnnooo — Sat, 14 Sep 2024 09:50:08 -0400

Hi @magflip,

Have you found a solution to your problem?
I am having exactly the same problem, as soon as I turn on my homemade printer using ramps 1.4 the hotend starts to heat up and doesn't stop till the whole printer shuts down with overheat protection error.
Any help would be appreciated.
Cheers

Re: Wrong Axis is moving:(

Dust — Fri, 13 Sep 2024 22:08:47 -0400

You would have to edit the boards pins file to have this fault, or perhaps setting the wrong MOTHERBOARD

Or plug the steppers in wrong location.

800px-Mark2-assembly-RAMPS-WIRING.jpg

Wrong Axis is moving:(

paul_schenker — Fri, 13 Sep 2024 17:41:31 -0400

Hi there,

I have set up a custom built printer using Ramps 1.4 and Marlin.
My problem is that when i want to move z the x axis moves everything else is completely working and ok.

Thanks for any help.
Paul Anton Schenker (Newbie in software(:P))

Re: Mega's AMS 1117 5V Getting Hot with RAMPS 1.6 + 128*64 LCD

Roberts_Clif — Sat, 07 Sep 2024 20:31:56 -0400

I replaced the AMS 1117 5V Regulator with a higher current board

Buck Converter

I also replaced the Ramps regulator from another link on my post.

Re: Mega's AMS 1117 5V Getting Hot with RAMPS 1.6 + 128*64 LCD

dc42 — Sat, 07 Sep 2024 08:16:09 -0400

This is completely normal. See [reprap.org].

Faulty thermistor readings on RAMPS 1.4

3dby3d — Tue, 06 Aug 2024 05:46:22 -0400

Hi, I've got an MKS Gen-2Z v1.1 control board based on RAMPS 1.4 and recently after starting the printer the heated bed readings are fluctuating. If I try to heat the bed the LED is lighting up and the bed starts to heat but without reading the correct temperature from it. The thermistor is OK I've check it out, so my guess is that maybe the SMD capacitor might be damaged. Does anyone had this issue before, meaning trying to replace the SMD ? If this is the root cause what might be the range tolerance for it to be correct replaced, the actual on the board is RVT 35V 10uF ? Or, does it work replace with a simple electrolytic capacitor ?

My RAMPS1.4 doesn't work when controlled by Raspberry PI 5 via Python3

civil.shakeri — Sun, 17 Mar 2024 13:22:40 -0400

Hello,
When I use my Windows device to control ramps1.4 (mounted on mega Arduino) via Python3, by g code like this:
...
import serial
import time

myPort = serial.Serial('COM7', 250000, parity='N')
time.sleep(1)

myPort.write('M302 S0\n'.encode())
myPort.write('G1 Z-50 F1000000\n'.encode())
myPort.write('M84\n'.encode())
...
everything is good and my step motors work. Next, when I connect this board to my Raspberry Pi5 device and change the 'myPort' code to 'myPort = serial.Serial('/dev/ttyACM0', 250000, parity='N')' connection is established and RAMPS1.4 light flashing to tell us that port is connected but my g code does not work and step motors remain motionless (without any error). First I thought that's issue relates to the Baud rate. So, to solve this problem I tried to change the baud rate in Raspberry Pi 5 via this code 'stty -F /dev/ttyACM0 115200' and checked it again, but that did not work either. Also, I tried any other standard baud rate and failed at all of them. And now, I don't know how to solve it.

Re: RAMPS 1.4 and external mosfets

ChileMaker — Fri, 08 Mar 2024 17:02:25 -0500

I wanted to add that with the external mosfet board attached, I can't get the heated bed to go over 33c even if I set the target temperature to 60c.

With the setup without the mosfet board, I have no trouble reaching 60c. It is not fast but it does not time out.

Re: RAMPS 1.4 and external mosfets

ChileMaker — Fri, 08 Mar 2024 07:24:19 -0500

Hi Dust.

Here are some pictures of the wiring.

1. The wiring at the module
2. The wire going to the headbed
3. The connector for the sensor at D8.
4. The power connector at the Ramps for the 11a.
5. Alternative wiring. I went ahead and tried a pass through on the power wiring
where I go from the PS to the external mosfet board and then to the Ramps at the 11a.
This diagram isn't a Ramps board, but it best shows the pass through I am talking about.
I do have a power connection to the 5a side of the Ramps, I never removed that.
6. Close up of one of the Mosfet modules I have.

Re: RAMPS 1.4 and external mosfets

Dust — Fri, 08 Mar 2024 06:32:27 -0500

@ChileMaker

how about some pictures of the mosfet modules and where all the wires actually go?

the MK52 is about 1ohm so pulls about 12 amps, most external mosfets should be able to do that easily

This doesn't really make sense from the description...

The connection form D8 to the module is just the on/off signal, it has practically no current. It normally goes to a optocoupler so is just turning on two LEDs (the blue one and one you cant see)

Re: RAMPS 1.4 and external mosfets

ChileMaker — Fri, 08 Mar 2024 06:13:23 -0500

Hi Dust.

I forgot to mention some of those particulars. The board is a genuine Prusa MK52 that is 210x250 and is 12v. It is not a Prusa printer but a Mendel variant that I upgraded over time. I had been just using PLA and having the bed go to 60c. Before I added the mosfet board, I had no trouble getting the heatbed to 75c, but it wouldn't get past that before the alarm sounded due to its taking too long to heat. I wanted to try some ABS I had so that's why I added the mosfet board. I have no problem getting the hotend to temperature so it can extrude the ABS. My Prusa MK3x has no trouble getting the bed to temperature for ABS, but it is a 24v system.

When powered up, the mosfet board's little red led is lit. When I attempt to heat up the bed, the little blue led lights. The red led for the MK52 I hooked up and tried another mosfet board (same type) and the same thing happened.

Re: RAMPS 1.4 and external mosfets

Dust — Fri, 08 Mar 2024 01:50:08 -0500

@ChileMaker

The wiring diagram and description sound correct

Perhaps your bed is just to to massive a current draw for the mosfet?

Re: RAMPS 1.4 and external mosfets

ChileMaker — Thu, 07 Mar 2024 19:29:27 -0500

I tried to add an external mosfet board to my Ramps 1.4 board, but it didn't work for me. I have a 12v S360-30 PS with three outputs.

This is what I did. I originally had two of the outputs from the PS go to the inputs of the Ramps 1.4 board, one to the 11a side and one to the 5a side. I took the third output from the PS and hooked it up to the external mosfet board on its PS connectors. Correct polarity on all of the outputs. I hooked the heatbed up to the external mosfet board on its heatbed connectors. I hooked up the sensor wires from the external mosfet board to the D8 connector on the Ramps 1.4 board where the heatbed wires were connected.

The external mosfet got really hot and the the heat bed didn't heat up. I surely messed up the wiring.

Should I have shared the PS output that went to the 11A on the Ramps board, with the input on the external mosfet board instead of using that third output?

Re: Preheat test damaged the board - ramps 1.4

Pencil42 — Sun, 24 Dec 2023 15:37:50 -0500

I changed the temperature sensor settings to 8 and I can see correct values in the lcd.

I can heat the hotbed and hotend separately.
I can power fans.

I tried to print a test cube and I broke the regulator again.