A10 - Resets [Solved]

[countzero]

A10 GT2560 V3
Marlin 1.1.8
2017-12-25 12:00 A10
HW version v2.20
Protocol 1.0
PSU: Generic

Autohoming works fine.
Leveling of build plate works fine.
LCD menu manual X Y Z axis movements and filament feeding works fine.

If I select Control > Temperature > Bed and set a value of 30 or higher the unit instantly stops working.

[countzero]

I removed the bed heating instructions from a random Gcode file on the memory stick:

Code: Select all

;M140 S60  ;Heat bed to 60 degrees celcius
M105
;M190 S60   ;Wait for bed to reach 60 degrees celcius
M104 S210
M105
M109 S210

I was able to start a print on a cold heat bed. After 3 minutes the printer again reset itself. This suggests the power supply or GT2560 V3 board is faulty and not the hotbed. I have ordered a replacement power supply.

Glass bed and aluminium hotbed are simply clamped together. Clips are clamped and not glued. Removing the clips will likely scratch the protective coating on the hotbed. You need to pry the clips open and release the clamping force before sliding outward(!) I have carefully removed all four clips.

[countzero]

NOTE: Symptoms may have been caused by a bad capacitor on the logic board. Modding the power supply may not have been necessary. Skip this post for now.

I fixed the problem of the original power supply.

The step load of the hotbed or extruder hotend triggered the short circuit protection of the power supply.

My 24V 350W power supply is somewhat similar to this 12V power supply:

http://imajeenyus.com/electronics/20151 ... supply.pdf

http://imajeenyus.com/electronics/20151 ... onents.jpg

Even the component numbers match.

DO NOT TRY THIS AT HOME. POWER SUPPLIES CONTAIN CAPACITORS THAT HOLD 360VDC AND NEED TO BE MANUALLY DISCHARGED FOR YOUR PERSONAL SAFETY.

I had to short C30 by soldering and bridging the solder islands to disable the short circuit protection (for testing purposes only).

Now the printer no longer resets. The LCD screen says "Bed heating" when I change the bed temperature to 50 degrees. Unfortunately the temperature remains at room temperature (25/50).

[_kaktus_]

Hi.


Maybe it's worth checking if the transistor that starts the heating is still working.
On the controller's board there is a LED indicating that the system is working. Have you observed its functioning

[William]

Hi,countzero
About the issue of the hotbed heating.
You can try to refer to the sch file of the A10
Then check the Mosfet of the motherboard normal or not:
https://github.com/Geeetech3D/Diagram/b ... .0_SCH.pdf

[countzero]

I disconnected all cables and removed the GT2560 V3 board.
So hotbed is not connected at all.
15A hotbed fuse was blown and has been removed.
I measure 3.7kOhm between 12V_BED and ground, so no short.
If I bridge the fuse the following current should flow: I = V / R = 24Vdc / 3.7k Ohm = 6.5mA
Diode test across zener D14 measures 0.185 voltage drop in one direction and high resistance in other direction, which is normal.
R33 measures 4.7kOhm.
I connected 24Vdc power supply unit to CON4 J1 and measured 24Vdc on pin2 to ground (USB socket metal shield).
MOSFET label reads "100N04-2M7 A AE T85B". Could not find a match for a datasheet.
MOSFET NMOS3 measures high resistance between source, gate and drain.
R29 measures 4.7k Ohm.

I have removed ripple smoothing capacitor C80 (35V 100uF) from the board.
I have removed polarity protection zener diode D14 from the board.

I switched multi-meter to current measuring and connected probes to [10A] and [COM] socket on multi-meter for measuring currents up to 10A.
I bridged the fuse holder MOMENTARILY with the multi-meter probes in current measuring mode (be careful as no fuse = possible smoke).
I measured 0 A of current. LED D6 lights up.
I connect multi-meter probes to [COM] and [+] and switch to mA measurement and repeat the measurement.
I measure 6.5mA of current.

With hotbed removed the GT2560 v3 board is stable.
With hotbed removed there is no path from 12V_BED to BED- to GND through MOSFET. So MOSFET is not suspect.
When I now connect the hotbed and repeat the current measurement the board remains stable and continues to only consume 6.5mA.
When I now connect the LCD screen and set [Control > Temperature > Bed > 30 degrees Celcius] and bridge the 15A fuse holder (dangerous), LEDs D6 and D9 light up, as well as the LED on the heatbed.

Problem solved.

Conclusion: Capacitor C80 (35V 100uF) had an internal short causing the 15A fuse to blow.

Advice: If everything else fails, consider removing capacitor C80 (35V 100uF) located next to the 15A fuse holder (for non technical users: in the corner of the board, close to the USB socket; you can twist / pull and remove without soldering).

I will order a replacement board and spare 15A littlefuse fuses.

[countzero]

I bridged the hotbed fuse as it takes 30 days for parts to arrive in remote Australia where I live.

Printer is now functioning and Geeetech A10 printer works GREAT !

I noticed the metal clips on the bed were actually mounted sort of upside down in my view. It is best to mount the clips as follows in my view:

• Metal clips should be attached with the flat side facing up. Benefits:

• 1. nozzle doesn't bump into clips.

• 2. smaller contact area underneath hotbed prevents scratches / shorts.

• Metal clips should be attached on the left and right hand side of the hotbed; not on the front or rear as it can create shorts more easily.

• Put some heatshrink tubing on the curved bit of each metal clip where the clip touches the underside of the hotbed. Heatshrink tubing starts shrinking at 100+ degrees Celcius and will withstand 60 degrees Celcius.

• When attaching the metal clips slide them on at an angle. Try to place the clip in position on the bottom of the hotbed first and then angle the metal clip upwards to snap it over the glass plate.

Tip: For simple and inexpensive bed adhesion printing PLA on a glass hotbed use the following method:

• Clean glass plate with paper towel, cold water and dish soap.

• In a small cup, mix a small amount of half and half volume sugar and water.

• Apply the water / sugar mix onto the glass plate with a paper towel.

[William]

Thanks for your sharing.
You can ask the sales to send you the replacement motherboard.