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,

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.

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,

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,

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.

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,

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.

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

CR.

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.

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,

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

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.:devious:

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

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

I am wondering since the damage is apparently already done and I can't seem to locate the cause(all the CB's look OK), would it be crazy to think I could use the X,Y, & Z axis with a secondary spindle mounted on the right side to do a job that is waiting? The axis all jog a reference Ok so I was thinking I could utilize the machine with a secondary spindle to get this job done. Otherwise it will be some time before I can find the fault and get the original spindle fixed or replaced. I want to finish the job ASAP but don't want to cause any more damage to the machine. It is just 2 halves of a plastic prototype and it should not take long to run them. Seems like a 'loaded' crazy question but it is a dilema and I almost started to run the parts already. Any advice welcomed!
Back to the toolpaths.

If you take the cast top off, it is probably not that hard to jury rig a motor with a flat or even V belt running the existing spindle.

A motor fault will not stop you using the X-Y-Z drives.

For safety remove the fuse from the motor PCB.
It is possible the fault is not in the motor PCB.

With the front switch selected for CNC operation of the motor, when Mach3 commands the motor to run with say M3 S2000 the relay on the main PCB should turn on. When you hit escape, it should go off.

I am going back to run another 12 hours of a fine engraving job...
I will watch this space every hour or so. Hope you can see in the dark because it is still yesterday! (2U):)

Hi Neil,
Thanks a lot for taking the time to help me work thru this situation. I have already rigged a mount for a RotoZip type motor on the right side of the spindle head. Since the material is plastic I figured it would work fine as long as the 25,000 or so RPM doesn't generate too much heat and melt the plastic(maybe air assist?). I originally was going to make wooden patterns and cast an aluminum prototype but since I have a couple pieces of plastic available thought I can save some time by cutting the actual parts from plastic. I may have to make molds for an injection plastic final part but this should be good for the prototype, and much lighter than aluminum. Thanks again for the tips and I like the idea for using the original spindle, it might work well for a high speed alternative with a pulley counter-shaft type of arrangement.
It sounds like you are keeping busy down there, another 12 hours engraving? I like engraving jobs too! OK, I'm off to see if I can get it set up and started. If I don't hurry it will be dark here soon too! Thanks again, and I'll let you know how things turn out.

I quit for tonight. I got the job set-up and ran it to a depth of about .125" in the pocket of the hand grip and about half of the outside profile on the hand grip. The material is a white polymer, and looks like polypropolene. I'm not sure what the best speeds and feeds are for this but the 25,000 RPM and most of the feeds I tried seemed to be generating a bit too much heat. Will have to try something different tomorrow and perhaps a different cutting tool. I don't have many choices as the motor only has 1/8" and 1/4" collets, but I need to use a small bit for most of the tight corners. Might have to use an inside profile with the .125"Dia and then pocket the rest out with the .250" dia tool. I took some pictures but with the white material you can't even make out the toolpaths. I'll try to finish it up tomorrow evening.
Regards,

I was able to finish the profiling of the plastic prototype with the add-on RotoZip motor, and I wanted to thank everyone for their posts and helpful information. A special thank you goes to Neil for not only the electrical tips and guidance but also the suggestions for using a temporary spindle until my Syil SX3 spindle is fixed.
I have noticed my E-stop switch is not opearable since the spindle motor problem and I will need to check it and make sure it is not faulty along with the components on the motor spindle board before moving forward with the spindle motor troubleshooting. I was unable to change the settings to get the E-stop to work, so I'm wondering if the switch itself might have failed? (Mach3 Error: External E-stop requested?) Will have to test it.
Regards,