Enco 110-1340

This shows how "3 wire control" works:

The AUX contact in parallel with the Start button keeps the contacter energized after you release the button, but doesn't allow the machine to restart by itself after a power failure.

-- Marengo

Then you need to trace out and draw what you have. Is there a contactor that reverses the motor?

When I reverse enginer a circuit I draw pictorial representations of the components that show the terminals and how they connect inside, in the same relative positions as in the device but spaced further apart. Then I draw each wire connection as I trace it, using freehand curved lines which are more distinct than straight ones where they cross.

Once I've traced and labelled all the connections I usually understand it well enough to redraw a neater schematic that shows the logical flow from source to load, left to right or top to bottom. The standard practice is a bit different from electronic schematics.

You can add labels to mark your progress by dabbing on white nail polish and writing with a fine permanent marker after it dries. As the Line and Neutral pass through contacts you can track them with a prefix number, as L1, 1L1, 2L1 ...

A good first step is to -completely- disconnect power and then tighten all the terminal screws. Also check for loose crimps when you trace the wiring.

--Marengo

Looking at the two images, the only switch there is the panic stop switch with the red mushroom handle. Normally, those are designed to lock pushed (stop state) and have to be either turned a bit clockwise to unlock, or pulled, depending on who made the switch. The two red wires with white terminal lugs look as though they should go to the start switch. One looks as though it has the number '4' on to, while the other is too out of focus to read any number, but since the panic/stop switch wires seem to be number '1' and '2' this makes sense.

The panic switch should be NC (normally closed -- that is when the switch is in the reset (not depressed) position, the two contacts will measure very low resistance between them. The "Start" or "Run" switch, however, will be NO (Normally Open) -- that is it has to be pressed to connect the two terminals.

Is it possible that you (or someone else) substituted the panic switch for the "Run" switch?? And where is the other switch? I see what looks like the mounting hardware for it above the hole where it goes.

Do you have a manual for the machine which includes a schematic of the wiring?

Good Luck, DoN.

Nothing was changed before the Start circuit started acting up. I hadn't even taken the lid off the circuits box since this was wired 20 years ago. Something failed on its own. And, yeah, the Start switch is numbered 3 and 4. I presumed it was some sort of breaker causing the problem, but the schematic doesn't even show them.

What changed was that contacts eroded and the machine vibrated.

I finally found a reference to manually closing the contacts to check them. Watch the red plungers in the center of the contactors when you press the start button.

--Marengo

That link you posted:

Seems to have an effed up upper diagram, because:

The "Maux" contacts are drawn normally closed, they should be normally open.

The way it's shown would turn the whole thing into a "buzzer" with power applied.

The "Stop" button switch has nothing connected to one side of it.

I assume you didn't notice those errors when posting a link that page.

Jeff

I didn't notice. I've been having trouble finding -anything- useful to explain control logic.

--jsw

Usually means a contact on the aux bypass is dirty and doesn't make. You are drawing the entire motor current through the contacts.

Might be the coil burnt but more like contacts.

The unit is a black box of plastic with screw connections or wires coming out.

It might be in the motor area due to size not in the switch area.

Trace wires see what goes where.

Mart> Nothing was changed before the Start circuit started acting up. I hadn't

In that case -- what was the hole for? Empty suggests that what may have happened is that the original start switch failed, and things were re-wired so the panic switch serves as the start switch (in which case the two loose wires should be connected together as a permanently pressed "start" switch, and the panic switch is serving as both start and stop. It *does* lock in the pressed state, does it not?

So was it bumped or moved recently? Perhaps the two loose wires were touching each other and are not longer doing so.

It would help if there were a schematic showing the switches and relays, so we could determine how it *should* be wired, in contrast to how it is currently wired.

Good Luck, DoN.

Instead of a single reversing relay, it is implemented here by two relays (contactors) side by side -- just below the existing switch and the hole where another one *should* be.

The wires carrying the three phase from one to the other contactor are what looks like brown, with hand-written labels on the crimp terminals.

This suggests to me that it was originally imported wired with a cap start single phase motor and was re-wired for three phase by someone else. This may also be why there is a missing switch. (Hmm ... does this not have the ability to run in reverse? Or is this in a lever switch There is a smaller contactor below the left-hand on the front panel?

Hmm ... I remember using a Jet of about the same design a number of years ago (maybe 20 by now? :-) and there was a lever on the carriage which could be moved up to go forward and down to go in reverse. On that one, I think that the red switch was purely for a panic stop switch, not for daily use. There may have been another switch on the panel as well -- a rotary knob along with the gearbox switches on similar knobs.

In this case -- the empty hole and the floating wires may have been for another indicator light instead of a switch. A pity that I don't have a manual for that machine -- or for yours.

There is a smaller contactor below the left-hand larger contactor, which likely implements the logic of the switching.

Indeed so.

Good Luck, DoN.