melzi heatbed issue - new for me anyway

Gday
Fairly new to 3d printer technology and hope I am sending this to the correct place.

I have an issue with the heat bed on my Aurora Z605.

I built it from a kit and after a few initial hiccups it was working well for 12 months. Then, the heat bed would not heat up.
I have changed the thermistor, new melzi 2.0 board and now the heatbed to a MK2B. Yet still no heat...
Feel like I have read every post about this issue yet cannot find a fix.
The resistance changes when i heat the thermistor but I do not get an output voltage on melzi heatbed connectors

Using repetier Host and tried Repetier and Marlin firmware - a copy of current Repetier configuration.h Configuration_h.txt
and pins.h pins.h.txt attached

Any advise appreciated and if I am in the wrong place please politely tell me where i should stick it..... Yeah I mean post it.
Thanks

Hi
Have you checked the wires to the heatbed. I had the same thing happen to me and it was the wires.

Hi
I have double checked everything I can think of and replaced anything that was suspect. there is continuity to the thermistor and the heatbed. One thing i just noticved is whilst there is no apparent voltage on the output terminals of the melzi - there is 12V when i use the positive and another negative (like the negative of the power supply input.)
Totally baffled still

Thats because the mosfet switches the gnd circuit of the bed, so if you measure 12v on both bed wires in respect to power supply negative, it shows that the mosfet is not being turned on.
possible cause is incorrect pin assigned in the firmware.

Thx Obewan. I have basic electronic knowledge and knew bugger about MOSFETs, so your explanation helped alot. Imdeed both bed wires do measure 12 V.
From my reading I believe the heatbed pin is set correctly and have no idea what to change if anything is incorrect.
I am surprised that a brand new board would have any issues at all, let alone the same as the board it replaces.
The extruder and everything else work fine.
Can anyone suggest a next step please.?
Pins.h follows

Quote

/****************************************************************************************
* Melzi pin assignment
*
****************************************************************************************/
#if MOTHERBOARD == 63
#define KNOWN_BOARD 1
#ifndef __AVR_ATmega644P__
#ifndef __AVR_ATmega1284P__
//#error Oops!  Make sure you have 'Sanguino' selected from the 'Tools -> Boards' menu.
#endif
#endif

#define ORIG_X_STEP_PIN         15
#define ORIG_X_DIR_PIN          21
#define ORIG_X_MIN_PIN          18
#define ORIG_X_MAX_PIN           -2

#define ORIG_Y_STEP_PIN         22
#define ORIG_Y_DIR_PIN          23
#define ORIG_Y_MIN_PIN          19
#define ORIG_Y_MAX_PIN          -1

#define ORIG_Z_STEP_PIN         3
#define ORIG_Z_DIR_PIN          2
#define ORIG_Z_MIN_PIN          20
#define ORIG_Z_MAX_PIN          -1

#define ORIG_E0_STEP_PIN         1
#define ORIG_E0_DIR_PIN          0
#define ORIG_E0_ENABLE_PIN      14

//29 on Melzi1284p A2
#define PROBE_PIN          -1    

#define LED_PIN            27

#define ORIG_FAN_PIN            4

#define ORIG_PS_ON_PIN          -1

// (extruder)
#define HEATER_0_PIN       13 
#define HEATER_2_PIN       -1
// bed (change to 12 for breakout pin on header)
#define HEATER_1_PIN     10 

#define ORIG_X_ENABLE_PIN       14
#define ORIG_Y_ENABLE_PIN       14
#define ORIG_Z_ENABLE_PIN       26

// MUST USE ANALOG INPUT NUMBERING NOT DIGITAL OUTPUT NUMBERING!!!!!!!!! (pin 33 extruder)
#define TEMP_0_PIN          7   
// MUST USE ANALOG INPUT NUMBERING NOT DIGITAL OUTPUT NUMBERING!!!!!!!!! (pin 34 bed)
#define TEMP_1_PIN          6   
#define TEMP_2_PIN         -1
#define SDPOWER            -1
// 31 [reprap.org] says 31, schamtic show pin 37 = PA0 which is arduino pin 31!
#define SDSS               31 
#define SCK_PIN          7
#define MISO_PIN         6
#define MOSI_PIN         5
#define SDSUPPORT 1  // sd card reader on board
#define ORIG_SDCARDDETECT -1

#define E0_PINS ORIG_E0_STEP_PIN,ORIG_E0_DIR_PIN,ORIG_E0_ENABLE_PIN,
#define E1_PINS

#endif

Thanks

One other thing that had slipped my mind - because it seemed to have no effect when using the previous board - is that the LED has only flashed when the initial firmware was uploaded and nothing since. However is never worked on the original board as well and printing was good then.
Cheers

looking at your pins.h and a melzi circuit [www.reprap.org] the pinout looks wrong,
I think you may need to select a sanguinololu 1.1 motherboard in the repetier firmware tool.

If I understand your meaning, according to the Melzi circuit the bed should be on pin 13 and the hot end on Pin 14....?
The hot end currently works well on pin 13 but i will change the firmware and see what happens.

I dont understand why I need too select the sanguinololu motherboard in the repetier tool - and cannot see it listed anyway...

Perhaps my setup is all screwed up from the begining so I will try to explain what I have done..
After reading so much I cannot be sure where I gleaned the information I am following so maybe everythinbg is not quite right from the beginning.....

For the Arduino IDE to talk to the Melzi board I needed to copy the "sanguino" flder from the arduino download into the "hardware" folder in the Arduino program folder.
Apparently this cannot be done with the later version of the Arduino IDE so I am using version 1.0.4.
This allows Arduino to see the boad as "Melzi 1284p 16Mhz" - If I use later version of the Arduino IDE the board does not show up at all.
Then when using the Repetier firmware tool the board appears as "Melzi board" but I dont see sanguinololu at all.
Then in the pins.h it states that the Melzi board is 63 so I have followed what is listed there....

This setup does allow repetier and marlin firmware to be uploaded, but obviously something is not correct.

Thanks

I think I understand your point a little better after more reading.
Extruder (heater 0) should stay on pin 13 and the bed (heater 1) should be on pin 12 if certain conditions are present and if they are not it should be on pin 14....?

strange, this layout of the melzi 2.0 board shows the hot end definitely on pin 14 and if the 2 connections shown by the red line are connected then the bed would be pin 13
Maybe you have a different layout on your board ?

I'm not sure if my layout is different, however I left the hotend on pin 13 and changed the heatbed to pin 12 instead of pin 10....... and everything started working in the way it should.
Next time anything stops working I will check the firmware before considering that the hardware could be at fault.
Thanks heap for your help and guidance. I have leant alot more and you certainly fixed my problem
Cheers