Electrical question

[sawkerf]

I have a 2004 PRT Alpha and as I've mentioned in previous posts, I've had a mysterious issue with the router contacts. During my last attempt at getting some help from ShopBot, Frank mentioned some correlation between the E stop and the router contractors. Honestly, I didn't have a clue what he was talking about ( I dont speak "electrician")but I have been thinking about that statement ever since. Here is what has me thinking; first of all, my router contractors work great, sometimes, then suddenly they won't work at all. Then, for no reason they'll work fine for a while again. I also have a frequent failure of the ZZero program. And also quite frequently I'll get an error message during ZZero, saying that the stop button had been pushed when it has not. So far, this has only happened when running the ZZero file and not during a cut file. In the 10 years that I've had my Bot, I've only pushed the E stop one time. Do any of you guys have any idea what might be going on here?

[Chuck Keysor]

Kip, sorry this won't help much, but I have noticed sometimes it takes someone to make the first reply to a post in order to get the discussion rolling...... So with that objective...

I am assuming you are talking about a "Contactor". Generally, a contactor is essentially a hefty relay dedicated to switching a big load, such as a motor. Since your machine is old, and relays and contactors are subject to age and load related failure because of their mechanical construction, maybe your contactor has gone intermittent. The contacts are most likely to fail. And if the contactor's contact ratings are not appropriately matched to the load, contact failure is more likely to occur. Even having a contactor with a rating way higher than the actual current being switched can result in contact failure, when a mechanism called "self wiping" will not work.

Someone with a volt meter, a schematic and basic electrical knowledge should be able to help diagnose if the contactor is bad or not,,,, assuming that it fails to work regularly.

As to your emergency stop button false triggers, I have had the same thing happen with my machine ever since I have had it. It is random, and I have changed grounding as directed by others, and thought the problem was gone, but then it pops up again randomly. That may be harder to figure out than the contactor..............

Good luck, hope someone who really knows these machines can chime in, Chuck

[dana_swift]

If you have been using the ShopBot for a solid 10 years, the contactors may be worn out. They are modestly priced, and the replacement contactor only needs to be equivalent to the original one- coil voltage, number of contacts and inductive AC current rating. Some units are rated in horsepower since contactors often switch electric motors on and off.

Chucks description is really spot on. As to the false stop, I started having that problem when I loaded the latest SB software. My hunch is its a latent bug in there somewhere. I have not gone back to the old software to be sure. If you are running the latest "and greatest?" consider reverting to the last version you used that ran well.

Hope that helps-

D

[sawkerf]

Sorry guys, I should have mentioned that I just replaced both router contacts last month at $100.00 each. They work great when they work, so to speak, but something is kicking in and keeping them from working all the time. Thanks for the comments though.

[sawkerf]

Oh, and I'm not sure what version I'm running but it is at least 2 or more years old.

[bleeth]

If you're running any 3.8 uninstall it and install 3.6.44 or 46. make sure you update the firmware.

[sawkerf]

Thanks Dave, I did that right after 3.8 came out. Any other ideas or suggestions?

[paul_z]

Kip,

Can you post a picture of your control box opened up? I may have the same series box.

Paul Z

[sawkerf]

Sure, I'd be glad to, although it might be a few days before I can get to it. Btw, I'm running version 3.6.46

[bleeth]

Try opening up your e-stop and cleaning it out as well.