SX3 spindle problem

[metalworkz]

Hello,
I have been fortunate to have a working SX3 with the early spindle board that is somewhat more controlled than the newer boards. While milling a tool for a brake press job last night the spindle speed became irradic and then it stopped. I had an error to the effect of "External E-stop requested" in Mach3 when this happened and now the spindle seems to be dead. Does not spin in manual or CNC mode. I am thinking maybe the small board behind the height gage slide might have shorted out, but any input from you guys will be appreciated. I will probably have to move the tool to my Gingery horizontal mill and finish it manually, but I need to start fixing the SX3 right away also.
Thanks in advance for your help!
Regards,

[neilw20]

Turn off power and remove the PCB's one at a time starting with the big one. Look for cooked tracks, which is then an indication something went to ground where it shouldn't and that will usually be far removed from where the burnt tracks are. The burnt tracks are a result of the short. The problem is that most parts of the motor control circuitry is at high voltage and ANY PART of the circuitry except the (opto coupled input to the big board) being momentarily shorted to ground destroys something. If you have any burnt tracks, it is very likely that the hall sensors in the motor will be dead too.
The damage will probably be obvious but what caused it may be obscure.
Examine with care not to disturb the evidence.
It is easy to get the smoke out, but hard to get it back in again. (oops sorry) My brain just threw a wobbly.

[metalworkz]

Hi Neil,
Thanks for the helpful reply. I will probably start taking things apart and inspecting them tomorrow evening. I have a feeling it is going to be a while before I get it running again.
Regards,

[metalworkz]

I have not started to look through the circuit boards or anything for the original spindle but I did work on a secondary spindle mount tonight. It is basically a trial setup and should work fine for routing wood. I have a set of patterns I need to make for an aluminum casting prototype I am making so I wanted to be able to do most of the pocketing and profileling with the CNC.
I had started to make the patterns by hand and it is surprising how you get spoiled to using CNC and don't want to work backwards. If all works well I will make a more permanent mount for this and post some pictures of what I end up using.
Regards,

[Crevice Reamer]

You have probably already done this, but just to cover all bases:

1. Do you still have the chip guard switch connected? It could be faulty.

2. Have you checked the power supply fuse?

3. Have you checked the motor fuse?

Chances are though, that your quill DRO slide has shorted against the control PCB. Removing this is the first thing a new owner should do.

CR.

[metalworkz]

Hello CR,
Thanks for the reply. I have not even been able to look at the machine yet. I had to finish the work that was in process on my Gingery horizontal mill and have not had time to look at the SX3 yet.
1) My SX3 is one of the earlier models and it did not include any safety switch on the chip guard, so that one can be marked off the list.
2) The machine powers on and the axis work fine, just no spindle rotation.
3) I have not even opened that back cover yet to look inside, but I wondered if there was any fuse etc. on the motor circuit. I thought I recalled seeing a fuse on one of the circuit boards the last time I had the cover off to fix the Z stepper coupler.
I think maybe the quill DRO is not the problem now as the display comes on and shows the Forward and Reverse directions but there is no spindle rotation. I'm afraid maybe it is the spindle motor itself, but I will start on it this weekend.
Regards,

[neilw20]

I refer you to the procedure on post #2.
The problem with the DRO is that MECHANICALLY the part that slides up and down behind the panel SHORTS SOME TRACKS to ground.
Please follow the previous procedure for the quickest analysis of your fault.

[Crevice Reamer]

The motor fuse is under the bottom rear panel, and located at the top of the big circuit board.

CR.

[syil canada]

i also had a customer with the same problem, like crevice reamer had mentioned the wires from the chip guard switch were striped and grounding out, that then fried the button board pcb. once we unattached those goofy wires and replace the button board, all was good again.

[metalworkz]

My SX3 does not have a safety switch wired to the guard. I have removed the guard a long time ago. I will probably go ahead and remove the front panel and at least insulate the button board pcb while I have everything apart if it is not burnt.
I plan on following Neils post to determine what has happened in the rear main box if anything and feel I should implement some of the things others have done while I have it all apart like hinging the back cover plate. I have added fans to the rear box and will try to get them wired and funtional also. I noted a minor problem in the fabrication of the main box as there is a path that chips can take to make there way into the electrical box. Might as well fix that while it's apart too.(I used 3M tape as a temporary seal last time I had it apart to fix the Z stepper coupler) My main incentive is to get the spindle operating again, and thanks to everyone with all the tips and help! I plan on taking things apart tomorrow and will post anything I can find out. Thanks again!
Regards,

[metalworkz]

Hello,
1)I removed the front panel and used electrical tape to insulate the circuit board from shorting to the height gauge slide. I did not see any evidence of shorts or burnt tracks when I had that apart, and there seemed to be plenty of clearance between the 2 parts. Then re-assembled.
2)I then moved to the back main control box and removed the 2 circuit boards and examined them for burnt tracks. I did not see any burnt tracks or other burnt components on either of those boards, and I checked both the fuse on the large board and the fuse on the BOB and both looked fine.
3)I removed the BOB and it too did not show any signs of burnt tracks or damage. Do I need to look more closely at the components to see any damage(with a magnifier etc.)?? I had figured the damage would be obvious but so far I haven't seen any signs. Is it be possible for one of the components to be burnt out internally where I would have to check with an ohmmeter etc to find the faulty part?
Regards

[neilw20]

All of the electronics except the control inputs are at a high potential above chassis. It is good that you have not found any obvious signs of damage.

Finding faulty components with a multimeter will probably be a waste of time.
Most components are too complex or dynamic for a simple measurement to be of much use.

AFTER REMOVING the PCB and ensuring E1 and E2 have no residual charge check the relay on the big motor PCB It has been known to fail. Measuring across D13 beside the relay should measure about 1100 ohms. Make sure the red lead is nearest the relay. I assume you have a digital multimeter.

Check the 2 big resistors near the corner of the PCB. They are in parallel and should read half of labeled value.

All of the socketed IC's are readily available, but first check the mechanical problems which are the most likely cause as you have had no smoke (yet)

Remove all plugs and physically check EVERY crimp connection by a gentle tug.

I have a good PCB in front of me hence the above comments.

You may be lucky !! .
and best of luck too...