Fixing the electrics in my old German mill Ruhla 250/710

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John Hasler
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Re: Fixing the electrics in my old German mill Ruhla 250/710

Post by John Hasler »

We call that the smoke test. Possible scores are working machine = 10, nonworking but no smoke = 8, some smoke but fixable = 6, flames that go out when you cut the power = 4, call the fire department = 0. I've done it many times on all sorts of electronic and electrical stuff and never scored worse than 4 (and actually gotten quite a few tens.)

I suggest disconnecting all the motors during your initial tests.
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liveaboard
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Re: Fixing the electrics in my old German mill Ruhla 250/710

Post by liveaboard »

I'm hoping not to blow the local power grid at least.

I'll spend a while staring at things before I give it the juice.
John Evans
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Re: Fixing the electrics in my old German mill Ruhla 250/710

Post by John Evans »

got my fingers crossed for you !! impatient sort that I am damm the torpedoes throw the fool switch !!
www.chaski.com
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liveaboard
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Re: Fixing the electrics in my old German mill Ruhla 250/710

Post by liveaboard »

I have to admit, I was basically ripped of for this machine.
The shop said it had a mechanical fault in the feed system but was otherwise ok.
7 bad relays??

Also a gear rack is missing that should slide the top in and out manually, and the users manual that came with it was the wrong one, and misprinted too.

Still, I'm optimistic that it will be a good machine one bright day in the near future.
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liveaboard
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Re: Fixing the electrics in my old German mill Ruhla 250/710

Post by liveaboard »

And it's an 8.
Doesn't work.
How aggravating.
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tornitore45
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Re: Fixing the electrics in my old German mill Ruhla 250/710

Post by tornitore45 »

If it was me with such anxiety level.
I would disconnect all power loads like motors. Then power up the thing with a couple light 100W light bulbs (each in parallel) and then in series with the line. Limiting the current to about (230/200) 1.15A Max. Cold filaments have low resistance giving low drop to exercise al the relays but limiting current into shorts and potential wiring errors.
The secret is limiting the smoke to gray color. Black smoke on orange flames is bad.
Mauro Gaetano
in Austin TX
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liveaboard
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Re: Fixing the electrics in my old German mill Ruhla 250/710

Post by liveaboard »

There is no smoke, the relays mostly don't engage, but sometimes I got the spindle motor to go.

It's inconsistent, sometimes the spindle ran when I held the button, usually nothing happens at all.
One time when I shorted one of the stop buttons against the case, the spindle motor ran and the indicator light came on too.
The indicator lights have a separate power supply, so if one is on it must mean the appropriate relay is on.

It worked for a few seconds after I switched the feed gearbox, then didn't, then did as I changed the gears again.
There is a safety cutout in there, so that's my next destination.

After that I'm looking for bad push button contacts or most dread of all, broken wires in the harness.
The main control push buttons are truly diabolical things, with multiple no / nc contacts and 2 with indicator lights in them.
The control box is set into a pipe so it can swivel, but the collar is stretched and loose, so the wires may have been abused there.

There are multiple safety cutout buttons too. Not simple though, multiple wires and contacts.
Each feed axis has a cutout relay that is normally on, those are working.

My usual method of repairing complicated things is to poke around until (as my first boss used to say) I stumble across the problem.

Hopefully, that will happen one of these days.

After the feed gearbox, I'll start dismantling the control button array so I can check the wires.
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liveaboard
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Re: Fixing the electrics in my old German mill Ruhla 250/710

Post by liveaboard »

Breakthrough!
Sort of.
I found a loose wire behind one of the stop buttons.
Now the spindle motor starts, locks on, and stops.
The feed is still nonresponsive and the spindle lock indicator light does not come on.
Still, now I literally have solid leads to follow.
This is good, really good.
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Bill Shields
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Re: Fixing the electrics in my old German mill Ruhla 250/710

Post by Bill Shields »

:D
Too many things going on to bother listing them.
John Hasler
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Re: Fixing the electrics in my old German mill Ruhla 250/710

Post by John Hasler »

Make copious notes so that you refer to them when it goes wonky again in the future.
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liveaboard
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Re: Fixing the electrics in my old German mill Ruhla 250/710

Post by liveaboard »

these are the notes, here on this thread...

Actually, I do have notes of connections on each relay as well as a lot of pictures.
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liveaboard
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Re: Fixing the electrics in my old German mill Ruhla 250/710

Post by liveaboard »

It works!

I made 4 errors rewiring the relays because I'm a bit thick, but found and corrected them because I'm brilliant.

It's still on the table and has a few mechanical issues to take care of before I move it to its place.
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