HELP PLEASE - 40W Chinese Laser x-axis sensor not working

Ok, so i have one of the Chinese 40W lasers and for the past 10 months its been fine, I have read so much about the build quality but it has done what i wanted it to do so i am happy. But earlier today when i turn the machine on, instead of going to its starting point (0,0) it is just scrolling right on the X-Axis.

the Machine initiall goes to the top right. as it has done every other time ive turned it on. Then it steps a little inwards which is where it starts. But when its stepping in, something is going wrong and it wont stop.

I have taken the rails out of the case to see if i can clean it a little. but its made no difference. I will try and take a video now and upload but i don't know what to do.

Any suggestions?
Thanks
Scott

So, it goes to the top right corner and then stops? If so, that means your endstop switches are working. But when it gets commanded to leave the top right corner, it just keeps moving? Does it bang into the other end and just keep trying to move until you turn the power off?

Do you have jog buttons on your control panel?

It keep going right until i turn it off. (goes mental when it hits the edge and really loud) and i cant get it to toggle on the system as its not even connected to the computer. Ive always turned it on. Let it set it self to 0,0 then plugged my computer in and away i go. Had a few problems with the belt recently. Could it be linked?

There is no active monitoring of the position of the carriage. It moves to the home position so it knows where it starts and then keeps track of its position by knowing how many steps it sent to the motor.

So, your problem is limited to a few things:

1. If you have jog buttons on your control panel, the right jog button is stuck
2. Your controller firmware got ***ed up
3. Somehow your steps per mm got REALLY screwed up. If you can't change this is your software, then refer to 2.

I am hoping your problem is just 1, above.

Thats brilliant. Thank you.

One thing has just changed. Now its not going to 0,0.

When the machine is switched off i move the head to the middle of the area. Now when i turn it on, the head goes to the top but is no longer going to the left. Its going to the top and going right again. and wont stop going right still.

There is no control panel on the machine itself. i dont know how i would test the firmware or my software as i cant actually get it to stay still while being switched on. The second i turn it on, it goes up and right n then mental when it gets to the end.

Thank you so much for you help so far. Do you have any other ideas?
Thanks
Scott

On your motherboard, possibly a short on the stepper IC? There is usually a STEP, a DIR, and an enable pin. DIR is set to 1 or 0 to control the direction of the stepper and the STEP signal is pulsed to move the stepper exactly one step.

If your STEP pin was shorted, the motor wouldn't move at all.

If something is shorting out your DIR pin, it would cause the motor to go in only one direction (also if that line was opened like a broken trace on the motherboard or broken pin). So, the firmware is telling it to move to the home position and then stop when it hits the switch, but because the stepper is going in the opposite direction, it never hits the switch.

To test things while the unit is on, just press the home switch by hand, so it things it made it home.

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Your stepper IC could also have blown. Do you have a picture of your motherboard?

I dont have a picture here, its at my office and ive left now. I can barely see anything on the motherboard though as i cut MDF and the smoke has covered EVERYTHING in a nice think layer of black s**t. (soot :p ) What would the stepper IC look like? there were a only a few things on the very small motherboard by the motor. or would i need to look at the main motherboard? as the other axis is working fine i thought it may only be the smaller one that is attached to the stepper motor.

sorry if im not making sense. Im explaining as best i can. :(

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Originally Posted by G-G

I dont have a picture here, its at my office and ive left now. I can barely see anything on the motherboard though as i cut MDF and the smoke has covered EVERYTHING in a nice think layer of black s**t. (soot :p ) What would the stepper IC look like? there were a only a few things on the very small motherboard by the motor. or would i need to look at the main motherboard? as the other axis is working fine i thought it may only be the smaller one that is attached to the stepper motor.

sorry if im not making sense. Im explaining as best i can. :(

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If it is the same as mine, it looks like this:

Attachment 265460

And the stepper IC is the one directly below the X stepper connector.

I am in the process of upgrading mine to a different controller and I'll be darned if I can't find my old one. But I believe the chip is an Allegro A4982 http://www.allegromicro.com/~/Media/...Datasheet.ashx

That just made me think of something. On some of these laser cutters, the X axis stepper and home switches are plugged into that flat ribbon cable slot (marked X-Motor-A). If yours is installed like that, check to see if that cable has wiggled loose a bit or if that terrible soot you talked about got into that connector and is messing things up. You can clean the contacts with a pencil eraser.

Thats great, as soon as i get back up the office in the morning i will try that and let you know how it goes.

Yes my motherboard looks exactly like that :)

Thank you :)

I didn't see which program you are using but if it's LaserDRW there is a "initialize" setting when you select the "engrave" tab. If you accidentally delete a decimal point the start position goes ballistic and you have to shut the machine off quickly to keep from destroying belts. It is real easy to get it off and it moves even while you are changing it and insists on keeping going even though you quickly change the parameters back. Software flaw that I have seen several folks complain about. Essentially there are two home positions: The first one is 0,0 and that is where the machine goes when first turned on. Then after going there it moves to the start position and waits for a command to start lasering. I have my "start" position set to X 27.5 and Y 14.5 which is the upper left of the spring holder for stamps. If I remember right you can confirm a software problem by removing the computer connection and powering up just the bare machine. It should go to home only. If so then you have a software problem with a parameter set wrong somewhere.

Quote:

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Originally Posted by buddydog

I didn't see which program you are using but if it's LaserDRW there is a "initialize" setting when you select the "engrave" tab. If you accidentally delete a decimal point the start position goes ballistic and you have to shut the machine off quickly to keep from destroying belts. It is real easy to get it off and it moves even while you are changing it and insists on keeping going even though you quickly change the parameters back. Software flaw that I have seen several folks complain about. Essentially there are two home positions: The first one is 0,0 and that is where the machine goes when first turned on. Then after going there it moves to the start position and waits for a command to start lasering. I have my "start" position set to X 27.5 and Y 14.5 which is the upper left of the spring holder for stamps. If I remember right you can confirm a software problem by removing the computer connection and powering up just the bare machine. It should go to home only. If so then you have a software problem with a parameter set wrong somewhere.

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With my coreldraw board, mine doesn't even move at all when you flip the power switch. It goes to home only after I press the the test switch, which incidentally also fires the laser (unless I have the LASER switch turned off)... not the safest in my opinion.

I have taken off and cleaned every connection i possibly can from the motherboard. but when i turn it on, it is not going to home. The Y axis goes home, but the x doesnt move. Then so when it gets up to the top of the rails the y stays still and the x moves right and wont stop.

Ive been looking at the sensors on the motors and how they act when they get to home. i feel like my X-axis sensor constant thinks that is it at home. its cleared between the sensor as there was some soot. but this is the only thing i can think of. again not sure if im making sense but if there was something stuck in the x-axis sensor then it would constantly be trying to find its starting point, but because the sensoring isnt clearing it keep movning.

does this make sense? im going mad over this thing.

Thanks
GG

oh and my machine is not connected to my computer. :) but it had always gone home then to x-2 y-2 .

Did you try pushing the home sensor by hand to see if the motor stops like I suggested?

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Originally Posted by G-G

i feel like my X-axis sensor constant thinks that is it at home.

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That is the complete opposite of what the motherboard is thinking. The motherboard tells the stepper to "go home." It knows home is to the left, so it would command the motor to go left until it hits the home switch to signal that it is home. Then it stops and waits.

But, your motherboard is telling the stepper to go left until it reaches home, but the stepper is actually going right. Obviously, it will never hit home, so it just keeps going and going. This routine is not brilliant. It has absolutely no idea that the stepper is going right instead of left. It has absolutely no idea that it has been searching for home for 20 minutes and should have reached it by now. It simply says, step the motor left until I sense the home switch. That's it. Anything else is far overthinking things.

Something is messing with the DIR pin on the stepper controller, or your stepper is plugged in backwards. If you haven't messed with the connections, then some foreign material may have gotten onto the pins of the stepper driver chip. You could have a solder fracture where the lead on the chip is not making good electrical contact. It may not have solder on the pin at all (famous in chinese electronics) and just the pressure got it to work at first, but eventually oxidation builds up until there is no longer a connection.

To control your steppers, the motherboard does a very simple thing. It sets the DIR pin high or low depending on the direction it wants the stepper to turn. It set the enable pin low to enable the stepper outputs, then it sends one pulse to the step pin for every step it wants the motor to make. That's it. That's all it does. Nothing more and nothing less.

Obviously only a very limited number of things could be causing your problem, but if you aren't going to actually look at them when people suggest, you are just going to continue driving yourself nuts looking at things that has nothing to do with it. Your home switch is NOT the problem because it isn't even involved in this. If the motor was moving left, hit the home switch, but just kept going, then it would be a switch problem. It is not a switch problem. And you can verify that easily for your own sanity by simply pressing the switch while it is moving and watch the motor stop moving (even if just for a moment.)

1. Try to press the home switch by hand while the motor is moving. If it stops, then it is something on your motherboard or the stepper cable is plugged in backwards.

2. Check to make sure your cable is not plugged in backwards (doubtful)

3. Check the stepper driver IC for something shorting out the pins. Check it for loose pins.

4. If you have a multimeter, grab the datasheet I linked to above and look at what voltage is on the DIR pin. Look at the truth table in the datasheet to see if that is correct.

5. If no loose pins, no cable flipped around, and the voltage on the DIR pin is what it should be, then you will need to replace the driver on the motherboard.

I hope I don't sound like too much of a jerk here. I am trying to help you. But unless you do the things I suggested in the order I suggested, I can't. Instead you are coming back after we spend the time to give you instructions and just post a bunch of things you tried that had nothing to do with anything I said and then just repeat again that it is doing the same thing as before.

Quote:

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Originally Posted by Retroplayer

That is the complete opposite of what the motherboard is thinking. The motherboard tells the stepper to "go home." It knows home is to the left, so it would command the motor to go left until it hits the home switch to signal that it is home. Then it stops and waits.

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I don't know how this laser does its homing, but very often other types of machines, when they do the homing, will go until they hit the home switch and then they will back off it. This will then be home. If this laser does the same, the home switch could be stuck in the activated state and the controller is trying to drive the laser off the switch, hence going the wrong way. Simple test would be to test the switch with a multimeter to rule out if this is the case.

ITS FIXED!!!

i thought i had taken every connector off the circuit boards and cleaned them, then i saw there was another EXTREMELY small circuit board hidden to the side of the motor itself. I took this off, took out one of the ribbon cables and noticed one of the metal connections looked burnt. Gave the cable a good clean and blew air into the socket, put it back and remounted everything and it seems to have done the job. Where it looked burnt it was built up with gunk. i think this was shorting it from the burnt connector to one of the other connections on the ribbon cable.

Sorry if i wasn't following everything you suggested, i was getting ahead of myself and getting really disheartened by it.

I really appreciate all your guys help. and thanks for persisting with me while i rambled on about stuff i had no idea about lol

Thank you! :)

Quote:

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Originally Posted by G-G

ITS FIXED!!!

i thought i had taken every connector off the circuit boards and cleaned them, then i saw there was another EXTREMELY small circuit board hidden to the side of the motor itself. I took this off, took out one of the ribbon cables and noticed one of the metal connections looked burnt. Gave the cable a good clean and blew air into the socket, put it back and remounted everything and it seems to have done the job. Where it looked burnt it was built up with gunk. i think this was shorting it from the burnt connector to one of the other connections on the ribbon cable.

Sorry if i wasn't following everything you suggested, i was getting ahead of myself and getting really disheartened by it.

I really appreciate all your guys help. and thanks for persisting with me while i rambled on about stuff i had no idea about lol

Thank you! :)

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Glad you fixed it and that was not something I would have even known about, so your non-conventional troubleshooting may have served you well here! :)

I am curious what that board is.

I hate when that happens! Now that it is working and since you will be the chief cook and troubleshooter on your unit in the future,, I would suggest getting meaningful readings around the circuit so in the future when it breaks you will know what the correct readings should be. Not just voltage but with the unit off check continuity on the switches so you know which way they are hooked up to actuate. Probably the biggest problem with the Chinese machines is the total lack of documentation of the electronics. You can stare at the mechanics and figure it out pretty quick but you need a map to troubleshoot the electronics.