GT2560 Rev A+ Board Voltage regulator issue

John107
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GT2560 Rev A+ Board Voltage regulator issue

Post by John107 » Wed Feb 21, 2018 8:07 am

Prusa i3 Pro B purchased 2018-01-28

Successfully printed benchy and some calibration parts in PLA without any issues then tried to print a cover for the main board - 6.5 hour print

Checked printer after ~ 2hours and could smell smoke so turned the printer off!

On inspection (after it had cooled) found the Voltage regulator (7812BG) was discoloured and the X stepper driver was burnt / charred

Please advise

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William
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Re: GT2560 Rev A+ Board Voltage regulator issue

Post by William » Mon Feb 26, 2018 4:15 pm

1.7812BG is work for the fan interface
2.You can try to check the wiring of mainboard
3.Try to install a new driver board A4988 for X-axis and you can get the result it works or not
-Keep your mind and try to test it. :)
-Everything will be fun!-Support all Getech printer.
-You can ask me the questions and I will kindly reply.
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John107
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Re: GT2560 Rev A+ Board Voltage regulator issue

Post by John107 » Wed Feb 28, 2018 8:04 am

Main board wiring checked and was good (it failed during a print)

Removed dead stepper driver and replaced it with another. Manual movement in software is not working.

Uploaded a test Arduino sketch and tested each socket with a working stepper motor and driver. X axis is dead.

Have contacted seller.

John107
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Re: GT2560 Rev A+ Board Voltage regulator issue

Post by John107 » Thu Mar 01, 2018 8:25 am

Turned off the printer last night and returned to it today to find it unresponsive.

Checked the USB connection and the LED's came on for a few seconds and then turned off - no connection to PC or display.

Tried an Arduino UNO using the same connection and it worked straight away - no connector or PC errors

Turned the main power on to the board, tested the amps using a clamp meter and got 5A with nothing turned on.

Removed the board from the printer and tested bare-bones - USB as previous no connection, LED briefly come on.

Removed USB and applied power - Inductor '150' and Voltage regulator became extremely hot after 30 seconds - I was surprised they did not melt.

I have included a picture of the initial stepper driver that failed - Do these have temperature protection?

The fuses are OK and I have inspected the board under a microscope and everything appears to be normal except the slight discolouring of the voltage regulator. Board draws in excess of 5 Amps with just the power connected.

Any suggestions?

[attachment=0]Board Snipit.jpg[/attachment]
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William
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Re: GT2560 Rev A+ Board Voltage regulator issue

Post by William » Thu Mar 01, 2018 7:05 pm

It looks like A4988 seems to be short-circuited before it comes to such a result
-Keep your mind and try to test it. :)
-Everything will be fun!-Support all Getech printer.
-You can ask me the questions and I will kindly reply.
-Respect others is the best way you can get help!

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_kaktus_
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Re: GT2560 Rev A+ Board Voltage regulator issue

Post by _kaktus_ » Thu Mar 01, 2018 11:33 pm

try like this:
disconnect everything you can from the controller board - cable plugs, stepper motors, etc.
turn on the power and measure the power consumption.

If it continues to flow 5A, it is very bad, it indicates a short circuit on the controller board.
In this case, shipping for repair.

If the power consumption is small, it means that the damage is in one of the disconnected components ...

John107
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Re: GT2560 Rev A+ Board Voltage regulator issue

Post by John107 » Fri Mar 02, 2018 9:41 pm

Hi kaktus,

I tried the main board without anything connected except the power connector (bare bones) and it draws >5amps.

To rule out any issue with the power supply I tried the board with just the USB connection and with a regulated lab power supply.

The board does not respond correctly with USB and draws >5 amps when connected to a power supply.

Fuses have not failed but has a short circuit.

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_kaktus_
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Re: GT2560 Rev A+ Board Voltage regulator issue

Post by _kaktus_ » Sat Mar 03, 2018 4:16 pm

As I wrote earlier, it looks very bad.
If you feel strong,
you can solder several PCBs from the diagnostic cells of the fault diagnosis.

Elements worth checking are the power supply on the PCB in the form of impulse converter and line stabilizers.
This is the first step.

kaktus

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_kaktus_
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Re: GT2560 Rev A+ Board Voltage regulator issue

Post by _kaktus_ » Sat Mar 03, 2018 4:56 pm

John107 I forgot about the most important ;-)

First perform a visual inspection of the PCB. Both from the bottom and from the top of the circuit board.
Looking for discolored and blackened. The former wil be indication of the impact of a too high temperature. A malfunction may occur here.

With such a large power consumption, some elements can get very hot (possibly damaged ones).
Carefully touching the components you will find these warmed up.
Be careful not to get burned badly.

Be very careful!
kaktus

Oaken3d
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Re: GT2560 Rev A+ Board Voltage regulator issue

Post by Oaken3d » Sat Mar 17, 2018 10:20 am

Having same issue, i have 2 gt2560 A+ and im unable to use 2 fans, if i connect 2 fans the Voltage regulator (7812BG) gets crazy hot in only few seconds, if i disconnect the fans everything works good, if i connect just 1 blower same problem. I try disconnecting everything even removing the steppers drivers and same issue connecting just the fans. I have exactly same issue in the two boards, i try to put a small heat sink but doesn't work, heat sink gets hot in 30 sec.

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