GT2560 V3 - atmega blown up

[Cubitus88]

Hello there!

I have bought two used GT printers, A10M and A20M.
A20M is operational, A10M seems to have a problem with control board.

Printer: A10M
Problem: Not booting up

Diagnostics:
-PSU power ok 24 VDC measured at the board connector.
-Lights on board, LED for VE - red, VB - red, 5V - red. (5V measured, 4,96 VDC)
-LCD screens, light is on, but screen is blank.
-All XYZ microswitch endstops LED is ON, permanently, triggering does nothing. On A20M its opposite, lights up only when triggered.
-General overlook of the board: Cracked slot for stepstick, but does not shortout with anything, ATMEGA chip fried marks, some pins blown off.

I think the last diagnostic is quite obvious. Need new board.

Question is can any of you folks, help me out and tell me what could have caused those pins to be blown off. Im trying to avoid situation, where I put in new board and see brief flash and smoke then back to where i began.

I have attached picture with marked which pins are blown off.




Best Regards!

[William]

Hi, You can check if there are three lights on the motherboard when you turn on the printer normally, you can try to reconnect the screen cable.

[Cubitus88]

I did check, see in diagnostics, points about VE VB.

But to point out again, on power up, on board all 3 lights are ON, red color (I dont know if they can change color to other).

Like I said, look at the atmega processor chip, the pins are blown. I reasearched pintouts.

Burnt out pins on ATMEGA chip.

ADC11 - analog pin for T2 (what is T2 on A10M?) (I guess its temp sensor 2, which one is temp sensor 2? hotend? heatbed?)
OC3A - digital pin for PE3 (what is PE3 on A10M?) (This is to ground to earth I guess?)
PL0 - digital pin for A STP (what is A STP on A10M?) (There is no A axis stepstick on my board)

Can you help out now? I want to be 100% sure before I replace board that it will NOT burn again.

[William]

Hi, If there is a problem with the chip, it may be caused by improper operation, and the motherboard needs to be replaced.
You can refer to this motherboard schematic diagram: https://www.geeetech.com/download.html?download_id=43

[Cubitus88]

I agree, that improper use lead to that, thats why I have to buy board to make it operational...

Can you tell me which thermistor is the T2 (temperature sensor 2) on A10M? or it is not used?

I think I can ignore the blown A-step pin problem, for now.

What worries me is T2, please answer that one, and tell me how to check thermistors so i know they are ok and not shorting out.

If there is a short out one of thermistors then I will blow up new motherboard for 100% as it leads directly to the chip.

[William]

Hi, You can try to measure the continuity of your hot-end line,
Determine if there is a short-circuit condition on the hot end wire.

[_kaktus_]

Hello Cubitus88


I've read your posts and I think you have enough experience with electronics to run this printer successfully.

However, at the moment the diagnosis can be difficult because we don't know what happened before you bought the printer.

So I recommend caution.

For starters, it's good to disconnect all wires from the controller board. Stepstick modules too.
This is, of course, what happens when you run the next controller board.

If the controller starts up correctly (after the main power supply is connected), you can connect individual peripherals in turn and observe the behavior of the electronics. Connect the cables when the power is off.

If you have the right soldering equipment buy the microcontroller itself. The software is available. I expect that all fusebits will be configured automatically during firmware upload.

If the MCU in your controller board is destroyed and there are visible signs of burnout, a short circuit must have occurred.


There are diagrams for controller boards available in the forum. If you are not able to find them, please let us know.

[Cubitus88]

Dear All,

Geeetech parts arrived finally, 40 days by standard shipping.

I replaced the motherboard, however Im not out of the woods yet.

my LCD 2004 is showing me 2 lines of blocks.

******
Diagnosis:

1. Checked the ribbon flat cable, reinstalled it on both sides, ports are in good order mechanically, they hold the ribbon down quite good.
2. Checked the ribbon flat cable by multimeter, nothing broken, all lines have good connection.
3. Checked 3 leds on motherboard, all light up. Power supply is giving 23.9 VDC.
4. Reloaded firmware via your avrdude like program, only .hex files for A10 and A10M.
5. Connected by repetier and tried to control the printer.

Result:

Im pretty sure the flat cable, motherboard, and lcd are good. It is a firmware problem. I only have a10hex and a10mhex, without and with touchprobe versions.

-reset button on LCD is working, if i mismatched the pins, then adressing would suck and i dont think it would work. So does the turn dial potentiometer, i can hear silent clicks and beeps of browsing through menu.
-when connected to printer via repetier, I can connect, I can turn on heatbed, I can turn on hotend, I CANNOT move or home any axis.
-when loaded with A10 hex file for touchprobe, i get m999 error for probe not connected (which is as expected, I didnt install probe yet).

Conclusion:

I think that files for A10 you have on your site, are missing something crucial for firmware.
Can you give me full arduino sketchup?

[Cubitus88]

Thats how it looks like.

[Cubitus88]

Ok.

I give up on electronics in your printers.
Im soooo behind costs and repair for customer timetable that it is just silly.
I have cannibalized my personal A20M, took out the LCD.


And put it on tests with SAME BOARD, SAME RIBBON FLAT CABLE, just reloaded firmware for A20M hex file.
And oh what a suprise it works....




I dont know whats wrong with your firmware, tried to push it though by arduino, tried to push it by avr dude.
This replacement board just does not want to work with 2004 LCD if you load it for A10. Firmware, firmware and firmware again.

And no.... it is not... this // define discount reprap LCD kind of issue, that you can find on forum.

I will just 3d print casing for this LCD from A20M, and edit the software endstops so it doesnt crash, I guess thats about it with differences between A10 and A20 models.

Im...so unhappy, with money lost on this business I could have bought whole new printer.

Well its time to put some 32 bit board and touch TFT into remains of my a20m.
Dont get me wrong, I happy with mechanical side of geeetech products, superplate is simply fantastic...but electronics or firmware...sigh.