[Yellowhair]

Hi everybody, totally snookered, my Chinese 3020 power supply finally gave up the ghost yesterday and is totally beyond repair.
Is there anyone out there that has a power supply for the 3 Axis machine?
Is there anyone out there who could tell me how to build (put together) an equivalent power supply.
I am full of confidence in my fellow CNC'ers.

Best regards

[john-100]

why do you think your power supply is totally beyond repair.?

is the power supply a switch mode power supply or
a linear power supply ?

different manufactures build their own versions of the Chinese 3020 machines
using different electronics

a photo of the power supply , stepper drivers and spindle drive will help

john

[Yellowhair]

Thank you John, I will get some further information together: In the meantime here are a few photo's of the suspect board. This power supply let me down before and I replaced a mosfet chip and it was ok. This time I replaced the Mosfet chip again and it hasn't solved the problem. Hence my thoughts being the power supply is beyond salvage. Any advice gratefully received.
Best regards,
Custer

[john-100]

looking at your photos
it looks like the FET is not fastened to the heat sink and may of over heated

it looks like the resistors used to measure the motor current and limit the current through the opto isolators LED are OK

I will have a look for the diagrams of the board and post more tomorrow

John

[Yellowhair]

Hi John, the FET was disconnected at that time ready to solder a new one in place.
Here are some more photo's.
Many thanks for all your help.
Best regards,

Custer

[john-100]

from a post here on cnczone

YooCNC 3020 ZD - Spindle PCB
Attachment 419342

another version off the net
Attachment 419340

depending on your local mains voltage the DC supply to the spindle could be 50 to 60V depending on the load on the spindle

( stepdown transformer 220V to 36V AC multiply by root 2 for rectified DC voltage = 50V DC
in my location mains supply is 243V to 248V depending on time of day DC supply
at 248V would be 57V DC - depending on the transformer regulation off load the transformer output could be 6 to 10% more ! )

if you bought or made a PWM speed control it may have to work with a 70V DC supply

possible ebay control ?
Attachment 419364

https://www.ebay.co.uk/itm/DC-PWM-Mo...2aba%7Ciid%3A1

john

PS
whats the length and width of the board ?

PPS
I see you posted as I was typing
and the loose FET was a red herring

[Yellowhair]

Hello again John, the physical board size is 12cms x 5.5cms.
Thank you for the other information but I have no idea what it means, sorry but electronics and me don't mix.

Best regards,

Custer

[john-100]

do you have a multimeter ?

if so check you have about 50V dc at fuse 1 and the two 1 ohm resistors in parallel measures 0.5 ohms

while a faulty FET can be the problem
some times the 8 pin IC (NE555) can fail to drive the FET gate with the PWM signal to turn the FET ON so the spindle does not run


from another post when I helped a member rewire a 120V machine to 220V

this is the transformer used
Attachment 419390

the spindle power supply from post 6

Attachment 419392

john

[Yellowhair]

John I'm so sorry I fear I have lead you down the wrong path, you see the spindle is running at full speed all the time, as soon as the power switch is on, and there is no difference when the spindle switch is on or off, neither does the emergency stop button do anything, the spindle just keeps going.
So sorry I didn't make myself clear.

Best regards
Custer

[john-100]

if it running at full speed
either the FET is short circuit between source and drain
or the NE555 IC output is high (+4 to 10V)

the FET is turned on when the gate is +4V or more with respect to the source
normally the NE555 switches between 0V and +12V
the speed control adjusts the ratio of on to off time (the longer its on the faster the spindle runs)

john

[Yellowhair]

Hi John, I have tried to do the tests you asked and if I have done them correct then the results are:Across fuse 1 I have a reading of .025
across the the 1 ohm resistors it is 0.00 this is with a very small digital multimeter I have had for years and not confident in it's use.

Best regards

Custer

[Yellowhair]

Hi John, what I have done is ordered a new FET and a new 555 chip I am hoping that after a bit of soldering this weekend I should be up and running again.
I will keep you informed of any progress (or lack of it).

Best regards
Custer

[Yellowhair]

Hi John, all I can say is you are a STAR. The new FET and NE555 chips turned up this morning so I soldered the new FET in place, tested it and everything WORKED without even having to solder the new NE555 into place.
YIPPEEEE.

Best regards

[john-100]

good to know its working

john

[Sterob]

Nice work John!
I am very jealous of that skill.....
Steve

[john-100]

this should help with the repair of the spindle speed control



John