Megatronics v2 problems

I have an unbranded 240v 20Amp 12v powersupply and a Megatronics v2.0 kit: [www.amazon.co.uk]

Main problem:

My heatbed mosfet is getting ridiculously hot when the second 12v line is hooked up whether the heatbed is on or off. I put a small heatsink on it, but its still far too hot, burn your skin hot. The heatbed works but I wouldn't like to have it on for more than a few seconds. Does anyone know why that might be, if its a common problem or if it could be solved with a resistor or something simple like that? I've tried it both with a second 12 line and connected in parallel with the first 12v cable.

Is 20 Amps too much?

LCD problem:

I also can't get my LCD 12864 to work, the dial, the speaker and the light button work but the screen just flickers. I don't know if that could be a related issue. I have uncomment the line: #define REPRAP_DISCOUNT_FULL_GRAPHIC_SMART_CONTROLLER

Does anyone have any idea I haven't been able to find much online about it at all.

Edited 1 time(s). Last edit at 01/14/2014 07:28PM by prusanoob.

LCD problem:

// ==> REMEMBER TO INSTALL U8glib to your ARDUINO library folder: [code.google.com]

Maybe you forget????

Regards,

Henri

I installed the u8glib and everything compiled fine and uploaded.

I think I may have a bad part to be honest, but I'm not sure.

I'll try it again later, maybe I was using an old version or something.

Any idea of how many amps I can or should put through it?

I recently bought the exact same bundle, and it came with zero documentation. I have already popped the +5V on-board power regulator, thanks to one of the two display ribbon cable ends being crimped on backwards and my own stupidity for not checking the stripe on the cable since the connectors were keyed. (Not that I could have identified pin 1 on half of the connectors anyway without silk-screened numbers or dot/notch hints on the boards, but I digress.)

I'm curious how you hooked the display up, as in which cable on the adapter card goes to which connector on the LCD? I flashed Repetier 0.91 built with the RRD graphic smart controller drivers, but only the back light seems to work. I cranked the contrast potentiometer slowly until there were black boxes on the screen, which might help in your case if you are not seeing anything on the display. I don't know if my display board wasn't damaged by the bad cable, so I can't offer any other hints to fix your display since I never got mine working outside of the back light.....

I have the same issue with the heated bed controller... just put in line with an ammeter and is pulling 5.66A which is right for 11.8 volts to the FET and 2.0 ohms for the bed but its liquifying the solder on the base of the board.... too hot i think!!

My LCD worked fine as long as i had megatronics V2.0 selected on the configuration.h think its option 701.

My 5V reg is also an issue, its putting out 4.08 Volts only so could be faulty..

The mosfet shouldn't get hot when the heatbed is off, since there is no current flowing, so that is a puzzle.

It's possible to overheat the mosfet if you have PWM turned on for the heatbed, check you have it set to bang-bang control.

Some cheap suppliers substitute a mosfet with non-logic level input, which don't switch on enough at 5V. They also substitute lower spec parts for the screw terminals. Could also be dodgy soldering around the connections. It only takes a fraction of an ohm to generate excess heat.

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Have bang bang set but continues to get dangerously hot (what temp does solder melt at?). I wonder if its a cheap or faulty FET, since my 5V reg is only putting out 4V could it be over-amping the FET when it is not fully on?

I wouldn't worry about solder melting at anything under 165 deg C, and higher is the usual norm (especially if it's not leaded solder). Lead/tin solder in either 63/37 or 60/40 should start to melt at 183 dec C, though it might get soft just before that. That said, driving the FETs hot can lead to them being damaged.

I would definitely fix the 5V side of things also. driving the FET at 4V (or less) may not be switching it on properly, depending on what FET it actually is on the board. Does the FET on the actual board have any markings that tell you what it is?

I also have a problem with the LCD not working. Without any LCD options made in the config file the board uploads ok and it responds in 'printer interface' correctly.
No documentation at all about the LCD screen ; when the //#define REPRAP_DISCOUNT_FULL_GRAPHIC_SMART_CONTROLLER is enabled the Arduino compiler reports errors in the u8glib files. (u8glib is in the libraries folder)

The screen is described as 'SainSmart Megatronics LCD12864 intellegent'
Has any one got these displays working, and what 'should' or 'should not' be enabled in the Arduino compiler ?

These are the errors the compiler reports :- ( makes not much sense too me !! , about to give up and work it without a screen )

In file included from /dogm_lcd_implementation.h:38,
from ultralcd.cpp:28:
dogm_font_data_marlin.h:13: error: 'u8g_fntpgm_uint8_t' does not name a type
dogm_font_data_marlin.h:172: error: 'u8g_fntpgm_uint8_t' does not name a type
In file included from /dogm_lcd_implementation.h:40,
from ultralcd.cpp:28:
ultralcd_st7920_u8glib_rrd.h:43: error: 'u8g_t' was not declared in this scope
ultralcd_st7920_u8glib_rrd.h:43: error: 'u8g' was not declared in this scope
ultralcd_st7920_u8glib_rrd.h:43: error: 'u8g_dev_t' was not declared in this scope
ultralcd_st7920_u8glib_rrd.h:43: error: 'dev' was not declared in this scope
ultralcd_st7920_u8glib_rrd.h:43: error: expected primary-expression before 'msg'
ultralcd_st7920_u8glib_rrd.h:43: error: expected primary-expression before 'void'
ultralcd_st7920_u8glib_rrd.h:43: error: initializer expression list treated as compound expression
ultralcd_st7920_u8glib_rrd.h:44: error: expected ',' or ';' before '{' token

Hi allempty,

did you get your lcd to work?
i have exactly the same issues.

greetins
Oliver

Yes I did solve the problem.

There is a later u8g library that solved the compile issues, it's u8glib_arduino_ v1.1.15 zip found going to the u8g web page best.
I found that adding a library from arduino was a sure way of unpacking it in the correct directory. Read the attached instructions in the zip file.
Open up arduino and go to sketch menue, then import library having already unpacked it somewhere like the desk top.

the second problem i found was that the contrast pot for the first lcd display was a very narrow adjustment. The second replacement LCD was not as narrow but still difficult to get right.
I only discovered this by being sent a replacement display.
DO NOT BE TEMPTED TO ADJUST THE CONTRAST POT UNTIL YOU SEE SOME GRAPHICS APPEAR.
you must also have both ribbon cables connected as this lcd device is a serial arrangement. The schematic is next to useless for fault finding as I don't believe it's complete.
Not realising this I previously connected only the LCD cable not wishing to over complicate matters with switches and jog wheel.
The lcd ribbon cable goes to EPX1 on the lcd screen, the other goes to EXP2. You must have both connected.

I have not yet got the SD card working on the display board but the one on the megatronics 2 works ok.
The 'stop' switch does not function either but at present I am not to bothered about this.
Don't know what the jumper on the display marked DIR1 or CTRL is all about.
I'm following another topic to solve that one.

Would I buy again ?

The board is well made and it functions ok as far as I've got.
Information is very poor, if they published that it would help just to know what the jumper setting do.

BTW if you power from a 12V input be sure to remove the power jumper next to the USB or the board will be trying to power your computer and the little regulator on the underside of the megatronics board will get very very hot.

Quote
allempty
I have not yet got the SD card working on the display board but the one on the megatronics 2 works ok.
The 'stop' switch does not function either but at present I am not to bothered about this.

There's another thread on this site about these two issues. From what I can determine, the little adapter board provided in this package does not pass the kill switch or the external SD pins through to the Megatronics 2 board. It may be possible to add jumpers to the adapter board to jumper the ribbon cable pins to the correct pins on the Megatronics 2 board, but I couldn't figure out which pins to tap or if additional circuitry is needed.....