The dreaded magic smoke escaped

[Swede]

I'm bumming - Yesterday, I was cleaning and checking my FC 20 amp servo box, an older one with the silver case, and thought, "I'm going to add an external emergency stop switch." So I added a phono-style jack to the case, and put this in series with the internal NC emer-stop switch. Powered up, and I could not close the relays with the front button, energizing the axes.

In my stupidity, I used a jack that grounded the safety switch to chassis ground. Distinct smoke smell in the power supply board. Internal fuse is OK.

The unit:


The power supply side:


And the board that cooked:


Two things - 1) DON'T do what I did, obviously. An external STOP switch can be in series with the internal one, but no contact with the chassis.

2) How can I resurrect this with least cost/hassle? I have emailed FC. I am afraid that they will want me to send the whole unit in, and I'd rather not, but I will if it comes to it. If I can get just that board, I am 99% confident of a repair.

[Al_The_Man]

You need to trace the source of supply for the E-stop relay, most likely a circuit trace has opened up or a PS component has blown.
If the supply is the switching supply shown, they are hard to diagnose.
The Toroidal linear should be much easier.
Hopefully you have a totally hard wired E-Stop!
Al.

[Swede]

Thanks, Al. I received an immediate email response from FC on a Saturday, which was impressive. They are going to look for a board on Monday. If that fails, I will begin looking at a bit of troubleshooting. I need to find a schematic to do this.

The stupidity of this act by me is what hurts. I wanted an elegant external STOP switch that I could plug in, and why I went ahead with an uninsulated jack, I'll never know. It just didn't register with me that it was a bad idea.

Worst case, I can find a switching supply with similar (or better) characteristics, and replace the entire supply, but that would be expensive.

[Al_The_Man]

Do they, or will they supply a machine wiring schematic at least?
Phono jacks are not the best idea, as you found out, although if it had been the stereo version, you would have had two isolated contacts available!
Al.

[Swede]

Do they, or will they supply a machine wiring schematic at least?
Phono jacks are not the best idea, as you found out, although if it had been the stereo version, you would have had two isolated contacts available!
Al.

Yeah tough lesson learned. I don't think of myself as a dummy with electronics, but I was in this case.

FC has been very good to me in the support area. I'll go through my docs and see if there is a schematic. It might be possible to replace an individual component or two and get it going, but if a board is available, I'd pop for it.

The jack was actually a female "power" jack, the sort with an internal male pin, commonly used to provide power from a wall transformer. Argh, I'm still kicking myself over this one.

"If it isn't broken, don't **** with it!"

[BobWarfield]

Oh no!

We gotta get the Swede back up and CNC'ing!

Sounds like FlashCut is taking care of you. Good for them.

Best,

BW

[Swede]

Oh no!

We gotta get the Swede back up and CNC'ing!

Sounds like FlashCut is taking care of you. Good for them.

Best,

BW

After our chat, I am motivated to get my ancient web sit updated...

No word from FC yet, but it is early. Like many problems, if you throw enough $$ at it, this one will be fixable too.

In the mean time, I've got a lot of other work to do, like refreshing my CAD/CAM skills and looking at appropriate upgrades. I also stripped my machine down a bit, looking for corrosion, wear, any other problems. My shop has always had rust problems, but the machine looks pristine. What I did (seems to help) is to place an 18 watt "Golden Rod" heater underneath the base, and covered the machine with a breathable cloth. The heat goes up and makes a toasty tent, and did a great job inhibiting rust on costly ball screws and rails.

[bill south]

Hey Swede;
Welcome back to the zone! If you can find out what voltages the smoky unit supplied, replacement should be quite easy. Marlin P Jones has many PS's on the cheap. You can most likely scrounge parts off the old unit to make a decent high voltage supply. Really quite easy with a transformer, caps and rectifier. Simple schematics can be had from here on the zone. I'll bet the other voltages will be 12V and 5V DC.
Good luck and beware of the lightening that lurks in undischarged capacitors. It tickles.
Bill

[Swede]

Hey Swede;
Welcome back to the zone! If you can find out what voltages the smoky unit supplied, replacement should be quite easy.
Bill

Hello Bill, thanks - I'm getting some replies and hopefully will get this thing back in business with the correct board, but it's good to know there are alternatives.