Control Board issues

[MrJoatmon]

Yesterday, I completed building my Pro W. It seemed to power up okay and I could control the motors via the LCD and also through my Mac via Repetier fine. However, yesterday I had no power to the fans so I turned the printer off to try again today.

Today, I have switched it on again but I no longer have a working control board. On the control board, only one of the LEDs near the power cable are lit, but I'm quite sure that yesterday, two were lit. I also have a lit LED where the USB connects. Can anyone advise what may be the cause of of the board not working today?

I'm aware that this might be two separate issues, with the board not working and also the fans.

Thank you in advance!

[_kaktus_]

Hi


If you have a multimeter, measure the output voltage on the main power supply.
Then enter your readout here.

Also read the PSU parameters from the sticker.

Which versions of the controller board do you have

[MrJoatmon]

Thanks for the swift reply.

My multimeter is a bit old so it's an analogue reading, but looks like a solid 12V from the power supply (I also checked at the end of the power cable to the control board, just to make sure the cable wasn't faulty).
The board is the GT2560 Rev A+ and I think has the CH340 chip.

I've checked the fuses, and it looks like one of them has blown as there is 0v across one and 12v across the other.

Having removed the control board, I've looked on the back and found that the soldering at the + points is merged. Surely this is part of the problem??

Would this also have caused the fan problem?

[_kaktus_]

The fuse is worn or not properly seated
In my opinion, this soldering is not a problem.

I have pasted a schematic diagram on the forum, look for it will be useful for you.

And one more thing, your multimeter, is a treasure for me

[MrJoatmon]

I will have to try find a replacement fuse. Your schematics are helpful. Thank you. I notice that your schematics show a 5a and 15a fuse. Mine are 10a and 15a so I’m assuming there is some variation. I need to replace the 15a.

I’m no expert at this thing. Could you suggest any reason why the three common fans did not have power, even when the board was working? (Of course, they don’t work now because the fuse is worn, but before this happened, there was still no fan power).
I have tested the fans using a 9v battery and they both spin, so I think the fault lies somewhere in the board.
I saw a post that suggested placing a jumper pin on the JP2 but I have a feeling that trying that is what blew the fuse.

I was going to replace my ancient multimeter too! One man’s junk is another man’s treasure! Thanks again.

[_kaktus_]

Hi my retired buddy.

I will have to try find a replacement fuse. Your schematics are helpful. Thank you. I notice that your schematics show a 5a and 15a fuse. Mine are 10a and 15a so I’m assuming there is some variation. I need to replace the 15a.
...

The schematic diagram comes from the manufacturer. The diagrams are officially available to users.
It is possible that some electronic components will differ from the soldered ones.

...
I’m no expert at this thing. Could you suggest any reason why the three common fans did not have power, even when the board was working? (Of course, they don’t work now because the fuse is worn, but before this happened, there was still no fan power).
...

Eeeeeeeech
As you well know, diagnosis can be difficult to do even if it is done locally.
And I am far from thee, and I have not accompanied your actions.
And what should I tell you

I, too, am not an expert on this subject, I am only an excellent spoil In addition, it's terribly talkative when it doesn't need to be.
I can only state my opinion.

The desire to create a universal solution was caused by construction errors. These mistakes are cardinal and repeated. They have not been corrected in subsequent versions of the electronic circuit.
I'm not happy to write about it in public.

power section diagram

zasilanie_GT2560_A+.png (63.42 KiB) Viewed 11290 times

The fans use the VIN voltage for their operation.
This is the output voltage of the IC Positive Voltage Regulators 12VDC.
The controller is supplied with 12VDC voltage from the main power supply.
And we have the problem ready.

For correct operation, the stabilizer needs a higher voltage
Quote from the chip manufacturer's data sheet:

A common ground is required between the input and the output voltages. The input voltage must remain typically 2.0 V above the output voltage even during the low point on the input ripple voltage.

So it will never work properly.

...
I have tested the fans using a 9v battery and they both spin, so I think the fault lies somewhere in the board.
I saw a post that suggested placing a jumper pin on the JP2 but I have a feeling that trying that is what blew the fuse.
...

On this point, we are in agreement.
And this jumper JP2 is another misunderstanding.

...
I was going to replace my ancient multimeter too! One man’s junk is another man’s treasure! Thanks again.

ble ble ble

As you well know, this type of multimeter will be indispensable in certain types of use.

Sold off the stabilizer, put the cap on the jumper and everything will work better than new. A stabilizer would be needed if you wanted to use a 24VDC mains adapter. But then there will be other inconveniences.
In my controller board I also threw some pieces away.

I am passing on my opinions to the Geeetech staff, but the gentlemen have their opinions. So we see the results.
This mechanism can be easily redesigned to exist. And to function smoothly if necessary.

[MrJoatmon]

Thanks for your help. It is appreciated.
Sorry for my ignorance but which part is the stabiliser that you refer to?
And to clarify, is this correct:
1) Replace blown fuse (littlefuse/nano fuse)
2) Desolder and remove the stabilizer
3) Use a jumper cap on JP2

If this is correct, I just need to know which part is the stabilizer! And then I need to order the right fuse from eBay.

At some stage, it might just be easier (but more expensive) just to order a new GT2560 board from amazon!

[jone liu]

First, use a multimeter to detect that the fuse is bad. Second, if the fuse is bad, change a good fuse, remove all 4988, and re-power. (A bad 4988 may cause such a fault)

[_kaktus_]

That is exactly what I would do.

GT2560A+.jpg (42.3 KiB) Viewed 11248 times

Jone Liu added a very good remark.
It is worth checking it out.

By the way, I welcome you Jone

[MrJoatmon]

Thank you both. This is all incredibly helpful. I’m determined not to lose hope before I’ve started!
Aside from visually inspecting for any obvious short circuits and burn outs on one of the 4988, are there any tests I can conduct to determine if one of them is faulty?
Thanks again for your help and patience.