Thread: What does it do?

opto couple's are a LED ( light emitting diode ) , and a Light sensor , mounted close to each other in a " chip package " ,with an amplifier on the light sensor side to make it work , most the time with 6 or 8 legs , white bodied , some times black , there are a heap of different numbers on the "chips " from different manufactures , and just as many differnt types of opto couplers that have different voltage / amp handlering

they optically isolate the power , so if there is a spike on one side of the circuit board , it wont cross over to another part( there is a spark gap , some are good for 400 volts )
normally there TTL level / logic level / or 5volts 50milliamps

you would use them in good Break Out Boards , on the CNC so if one of your stepper drivers , blows up and puts 40volts down the TTL ( 5volt ) logic wires back to the 25pin printer port cable , the Opto Couple will get destroyed , but because the 2 sides are isolated by a gap with light transmitting the " logic " between them , the voltage spike will stop at the destroyed opto coupler and not travel through to the PC's mother board
OPTO Coupler for Keying

the optocoupler break out boards sold as Mach3 compatible on ebay need 2 power sources , one for each side of the optocopouler , there is no use in using the Jumper supplied to supply both sides with the same power supply , the ?? 40 volt spike , will go around the optocoupler ( through the power supply ) , pull 5v from a USB plug to power the PC side , and provide a 5volt voltage PSU for the CNC side , if there is a melt down on the CNC side , your PC will survive , or use two 5V PSU's

If it's in the power supply, it means it's a switching type, and the optocouplers are used to provide feedback to the voltage regulation circuitry so it can maintain the required output volts while still isolating one side from the other.

replacing the optocoupler board , if there is one , ( they will be on the main board ) wont fix what blew the optocouplers up

Originally Posted by SawDustSniffer

replacing the optocoupler board , if there is one , ( they will be on the main board ) wont fix what blew the optocouplers up

The instructions that came with the mchine came with Chinglese very sparse instructions.
I connected the Centronics cable to the PC and blew the circuitbreaker in the mains powerboard.
After that neither the PC nor the CNC controller would work.
I got a new PC and a new power supply (the box with the holes in it) then had a tech look at the controlbox. He doesn't know anything about CNC but is an electronics wizard.
He told me the "Optical" thingie was blown and maybe something else. The fan doesn't start.
The seller wants to know which boards I want replaced and I haven't got a clue which ones they could be.
PCBsNumbered.jpg
I presume the XYZ1 boards would not be the culprits, they seem to get their power from the power box?

Originally Posted by SAISAY

I connected the Centronics cable to the PC and blew the circuitbreaker in the mains powerboard.
---
I got a new --- power supply
--- The fan doesn't start.

First off, i trust that you are no longer using a Centronics connector for the board?

Next, which fan doesn't start? The only fan that I can think of in the power section would be the fan on the power supply itself. Unless there is something wrong with the connections then that fan would start automatically when the PSU was plugged into the mains. try disconnecting everthing from the PSU and then connect a 5volt something which you know works (to make sure that the PSU has a load on it) to the 5 volt output terminals (or the 12 volt part if that is easier for you). If the fan then starts and the connected thingy works then the PSU is working. if it doesn't, then the PSU isn't working.

i relay dislike giving info on electronics from just photo's , it never ends well

PSU is obvious , puts out 5 volts and 12 volts , guessing by the lack of heat sinks on the Stepper Driver Boards , the stepper driver boards run at 12 volts ?

there are 5 5vlot logic wire's going into the bottom of the Stepper driver boards , they would be , +5v, negative ,enable , direction , pulse,
just above them there are 2 6footed optocouplers ( white chips ) and a 4 legged ???appears to be an "inverting buffer" ??
the Dir and Pulse would be connected to the optocouplers , the enable would be connected to the buffer

a buffer ensures the voltage / amps are correct after a long travel in the wire , it cleans up the signal of any magnetic interference , an inverting buffer swaps the signal so 5 volts in , is 0 volts out , 0 volts in is 5 volts out ,

the enable wire is set from mach3 and shuts the stepper drivers down when the stop button is pressed , i had problems with mine and it was the Mach3 " enable " setting that needed switching to "active low"

can you get a photo of the PSU terminals , and a photo of the break out board ( top left of picture )

the board on the bottom appears to be a 12volt too 5volt converter ,
are there any LED's on the stepper driver boards that turn on when power is applied to the board ???

Echoing SawDustSniffer's comment, please don't take anything I say here as gospel

The fan is some power supplies only runs when necessary i.e. when cooling is required. I assume that the tech checked the output of the power supply and didn;t just rely on the fan as an indication?
Chances are that the power supply puts out a single voltage and there is a DC-DC converter to provide 5V for the logic. Possibly the unseen board marked 3 or perhaps the one at the front - difficult to tell without more detail

The opto isolators would (logically) be on the interface board that connects to the PC - looks like the board on the left of picture marked 2.

Any chance of more pictures, especially of the connectors to the computer/motors?

I am afraid all this technical stuff doesn't mean a thing to me
What is a PSU?
I am just the go between the technician and the seller.
The controlbox is with the technician in Cairns, 2 1/2 hours drive from here so taking more pictures is somehow difficult
The fan sits on the exterior of the control box, I do not know whether there is a fan in the power supply, it is a sealed unit.
Fan.jpg
The power supply unit (The shiny box with the holes) is brand new.
The PCB #1 is the 4th Axis.
I guess the XYZ and 4th axes are powered by the inverter in the power supply unit and, as such, did not get blown?
That leaves, I suppose, the board to the Serial plug #2, the Centronics plug #4 and the Optical thingie.

Also, no I do not intend to connect via the Centronics plug again
I have now learned, the Centronics cable goes between the Control Box and the CNC.

A little clearer thanks to your picture.

I had assumed the fan was in the power supply not a separate one as shown. I would expect the fan to run if the controller box is turned on.

The picture also clears up some previous posts where you'd mentioned a Centronics connector. It's a strange (but probably cheap) choice for connecting the controller to the motors.

A PSU is a Power Supply Unit. The shiny box with the holes.
The one you have doesn't look very sealed to me, it is covered with mesh steel that is easily seen through.
When you mentioned a fan, I was under the impression that you were talking about the fan which is normally on a PSU. It probably does have one, but not necessarially so.
As Ken says, can you get a photo of the PSU terminals. They should be labeled 5v, or 12v, earth, etc
The other advice I gave is still good, test the PSU to see if it is working.