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Table Saw Failure

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Table Saw Failure

Postby Rod » 15 Nov 2018, 23:34

My DEFT table saw stopped working this afternoon. I cut through a small piece of maple with no problem, switched off, repositioned for another cut but it wouldn’t switch back on.
The breaker hadn’t tripped so any advice as to where to look further?

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Re: Table Saw Failure

Postby kirkpoore1 » 16 Nov 2018, 06:12

Rod wrote:My DEFT table saw stopped working this afternoon. I cut through a small piece of maple with no problem, switched off, repositioned for another cut but it wouldn’t switch back on.
The breaker hadn’t tripped so any advice as to where to look further?

Rod


First check would be to make sure you have power. Maybe the cord has come loose. After that check the switch.

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Re: Table Saw Failure

Postby 9fingers » 16 Nov 2018, 09:36

Rod
If you are unable to sort it out just let me know what tests you have done and the results and I'll see if we can sort it between us
Cheers
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Re: Table Saw Failure

Postby StevieB » 16 Nov 2018, 10:01

Does the switch stay 'on' (or in) or does it feel as if hte switch is not engaging? As others have said - most likely is the something simple like a loose plug or blown fuse, then the switch being full of dust, then on to more significant component failure.
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Re: Table Saw Failure

Postby Rod » 16 Nov 2018, 11:46

I didn’t get a lot of time yesterday with school runs and Grandparent duties, I’ll have a play today.
The on switch felt ok and the circuit breaker hadn’t tripped. Power was getting to it.

Image


Rod

Thanks Bob and your “Gas Fire battery charger” works.
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Re: Table Saw Failure

Postby 9fingers » 16 Nov 2018, 12:03

Rod wrote:Thanks Bob and your “Gas Fire battery charger” works.


Thats good to know! Thanks

Assuming you are still in trouble with the saw after you have had a chance to play, please could you take a photo of the DOL starter/NVR with its cover off for your next post.

Thanks
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Re: Table Saw Failure

Postby Rod » 16 Nov 2018, 12:45

Image

Image

Image

There’s also a door safety switch

Image

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Re: Table Saw Failure

Postby 9fingers » 16 Nov 2018, 12:57

With the power off,
Prod around on the contactor (upper block) and see which parts move - they look to be the lighter grey or bluish parts. Find your self an offcut of wood that will enable you to push the moving parts in. NOT a Pencil!!
Make sure that door is shut.
Turn on the power and push in the contactor.
Does the motor start?
Does the contactor hold in by itself and leave the motor running when you stop pushing with the stick or stop as soon as you release manual pressure?

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Re: Table Saw Failure

Postby Rod » 16 Nov 2018, 13:08

Motor does not start
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Table Saw Failure

Postby Rod » 16 Nov 2018, 13:16

Looking at the switches the top “on”
pushes the green contact

Image

That doesn’t work either

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Re: Table Saw Failure

Postby 9fingers » 16 Nov 2018, 13:22

When you did the test, did the contactor hold in despite the motor not starting?

if not, that suggests the contactor is not pulling in fully or you were not pushing it full in?

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Re: Table Saw Failure

Postby Rod » 16 Nov 2018, 15:59

It wasn’t retained even the slightest amount, it popped back out. I definitely pushed it as hard as I could

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Re: Table Saw Failure

Postby 9fingers » 16 Nov 2018, 16:33

Rod wrote:It wasn’t retained even the slightest amount, it popped back out. I definitely pushed it as hard as I could

Rod


OK fair enough. Lets try a different tack.
By far the most probable is failure (or ingress of dust) into the control switches.
Turn power off before making changes and back on to test each time.

Bypass the door switch by disconnecting the wires at the switch and connecting them together covering the joint with insulation tape.

Press the green button to test.

There maybe a reset button on the thermal overload relay. This is the smaller block below the main contactor. They are all a bit different so not easy to say exactly where this is and what it looks like.

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Re: Table Saw Failure

Postby Jjenks » 16 Nov 2018, 18:05

The bottom part of that contractor is an MCB that trips the coil wire. It should reset by pushing the blue button on the right, the red button is a test switch.
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Re: Table Saw Failure

Postby 9fingers » 16 Nov 2018, 18:22

Jjenks wrote:The bottom part of that contractor is an MCB that trips the coil wire. It should reset by pushing the blue button on the right, the red button is a test switch.


Sorry but that is wrong on several counts.

The red button is the stop switch and maybe combined with reset function. The blue button may indeed be to do with reset but looks distinctly like it is rotated to operate.
As clearly marked, the test function is built into the rotary current setting blue control on the left.
We have enough problems with members mixing up RCD and MCBs both of which live in a consumer unit.
Referring to the thermal overload relay as a
an MCB is confusing although as you correctly say trips the contactor cool but it does not break the power circuit.

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Re: Table Saw Failure

Postby Jjenks » 16 Nov 2018, 18:26

The blue knob on the left is for adjusting amperage setting. The blue knob on the right usually has two positions one for automatic reset and one for manual.
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Re: Table Saw Failure

Postby Jjenks » 16 Nov 2018, 20:35

Looking at your system more closely. As Bob mentions earlier pushing the grey parts of the main contractor in should start the motor. Make sure all the grey parts push in. If not it looks more like a power supply fault. The rest of the system is the control side for the coil of the contractor. Regardless of the safety switch or the "thermal overload" which must be in the automatic reset position, otherwise you would have to push the blue button on the right all the time.
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Re: Table Saw Failure

Postby Rod » 16 Nov 2018, 23:38

Still no joy.
The power cable initially disappears into a white box behind, what does this do?

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Re: Table Saw Failure

Postby 9fingers » 17 Nov 2018, 09:52

Pm sent
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Re: Table Saw Failure

Postby Rod » 17 Nov 2018, 17:02

Bob kindly came round and sorted the problem.

Nothing to do with the saw itself but some dodgy wiring carried out 9 years ago by the electrician ( me he says sheepishly - screw into the wire cable, not the insulation!! ).

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Re: Table Saw Failure

Postby StevieB » 17 Nov 2018, 17:18

Glad it's sorted for you - top marks to Bob, well done Sir! :eusa-clap:
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Re: Table Saw Failure

Postby 9fingers » 17 Nov 2018, 17:23

StevieB wrote:Glad it's sorted for you - top marks to Bob, well done Sir! :eusa-clap:


At least the motor did not have to come out. 3HP lump at arms length is usually a recipe for scraped knuckles at the very least.
A couple of hours out was a nice break from domestic chores too.

Bob
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Re: Table Saw Failure

Postby Andyp » 17 Nov 2018, 18:24

If I understand this right it is a wonder that the fault took 9 years to manifest itself.
I do not think therefore I do not am.

cheers
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Re: Table Saw Failure

Postby 9fingers » 17 Nov 2018, 19:20

Andyp wrote:If I understand this right it is a wonder that the fault took 9 years to manifest itself.


It is one of those cases with an intermittent load can take ages to show up. Eventually soot build up broke the circuit to an extent where the voltage difference did not cause it to flash over and start conducting.

Not serious in this application other than the nuisance factor. Had it been an electric fire or other more continuous high load, the heat build up could have done more damage.

Bob
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Re: Table Saw Failure

Postby Jjenks » 17 Nov 2018, 20:53

:text-bravo: great to have a relatively easy and cheap fix.
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