rewiring the black and decker r1450 radial arm saw problem

Thread Starter

LAOADAM

Joined Nov 21, 2018
273
Hi,
I'm rewiring a black and Decker radial arm saw R1450, I am not quite understand the switch it used as picture (4) attached. The manual said it is a Overload Protector, that has one wire in, two wires out, and a red button, the thing is the three wires all conduction no matter the button pressed or not, at the picture (3), the top left is the switch. what should I use to replace this Overload Protector?

At the picture (3), the bottom left is a kind of relay, I can't know how it works, may I use a AC relay to replace it?

there are four wires go into the motor, is this mean it is brake build-in motor?

Thanks
Adam

SAW.jpgDEWALT SAW.JPGSAW ELE.JPGSAW SWITCH.JPG
 
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shortbus

Joined Sep 30, 2009
7,965
The manual said it is a Overload Protector, that has one wire in, two wires out, and a red button, the thing is the three wires all conduction no matter the button pressed or not, at the picture
The overload is like a circuit breaker, it works on heat, from the load of the motor. It will conduct until the built in coil of it trips the breaker. When that happens the red button is pushed to reset the breaker.


At the picture (3), the bottom left is a kind of relay, I can't know how it works, may I use a AC relay to replace it?
The relay is because of the on/off switch being in a different place, on the front of the saws arm. Why not just re use it? Or if you are just using the motor for something else (not on the saw) a standard switch rated fro the volts and amps of the motor will work in place of the relay.


there are four wires go into the motor, is this mean it is brake build-in motor?
From a saw built back in the 1960's it has no brake. Two of the wires are for the starting capacitor.
Here is a link to the saw manual - http://vintagemachinery.org/pubs/detail.aspx?id=5876
 

Thread Starter

LAOADAM

Joined Nov 21, 2018
273
The overload is like a circuit breaker, it works on heat, from the load of the motor. It will conduct until the built in coil of it trips the breaker. When that happens the red button is pushed to reset the breaker.




The relay is because of the on/off switch being in a different place, on the front of the saws arm. Why not just re use it? Or if you are just using the motor for something else (not on the saw) a standard switch rated fro the volts and amps of the motor will work in place of the relay.




From a saw built back in the 1960's it has no brake. Two of the wires are for the starting capacitor.
Here is a link to the saw manual - http://vintagemachinery.org/pubs/detail.aspx?id=5876
Thank you.
1. I did a test, and there is a spark from the electric box I don't where, the motor start a moment and stopped. I guess maybe something wrong there.
2. there are four wires go into motor, resistance measurement: R (Black/White) = 2.3 Ω; R (Brown/Brown )= 8.2 Ω . R (relay coil) = 1164 Ω ?.
3. I made a diagram from the saw attached, I don't know whats wrong with it, I can't figure out how it works. seems the capacitor is separated after assisted start?
4. There is not a circuit diagram even on the manual.
Best.

R1450 DIAGRAM.JPG
 
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shortbus

Joined Sep 30, 2009
7,965
3. I made a diagram from the saw attached, I don't know whats wrong with it, I can't figure out how it works. seems the capacitor is separated after assisted start?
Yes, there is a centrifugal switch on the rotor to remove the capacitor after a certain speed is reached. Did this work before you started working on it?

Your explanation is hard to follow. From what the manual said it can be wired to work on 110 or 220 volts, do you have it wire for the voltage your using? Where is this spark coming from? The mains plug, the on/off switch, or somewhere else? Your drawing doesn't make sense to me nothing is labled as to what it is other than the relay and cap nothing else is a normal(to me) reference.
 

Thread Starter

LAOADAM

Joined Nov 21, 2018
273
Yes, there is a centrifugal switch on the rotor to remove the capacitor after a certain speed is reached. Did this work before you started working on it?

Your explanation is hard to follow. From what the manual said it can be wired to work on 110 or 220 volts, do you have it wire for the voltage your using? Where is this spark coming from? The mains plug, the on/off switch, or somewhere else? Your drawing doesn't make sense to me nothing is labled as to what it is other than the relay and cap nothing else is a normal(to me) reference.
Thanks.
Firstly sorry of my poor English and electric knowledge.
I supplement the diagram, and the power input is 110v.
I don't know how the capacitor and centrifugal switch works, I just have it for few days. Because the front heat switch just on/off the power line, thats why I guess the relay is for remove the capacitor.
The spark I believe happened in the electric box of the picture (3), I didn't check out any where short yet, and I dare not try power on again.

I'm thinking if I can use the capacitor start the motor and keep the capacitor connected instead of remove it like some other motor do.

Best.

R1450 DIAGRAM.1.JPG
 
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shortbus

Joined Sep 30, 2009
7,965
I don't know how the capacitor and centrifugal switch works, I just have it for few days. Because the front heat switch just on/off the power line, thats why I guess the relay is for remove the capacitor.
I doubt the relay is for the capacitor, the capacitor is controlled with a switch that is inside the motor and turns off the cap when a certain speed is reached.

I'm thinking if I can use the capacitor start the motor and keep the capacitor connected instead of remove it like some other motor do.
Doing that will cause the capacitor to fail, and pretty fast. Many times the capacitor is the reason a motor like this doesn't run, because it has failed from old age or other reasons.

I supplement the diagram, and the power input is 110v.
Your diagram is still wrong, and not how a motor is wired. Here is a picture of how they are wired, but not using the thermal switch -

1599056363082.png Maybe you can Google and read more about "capacitor start motor".
 

shortbus

Joined Sep 30, 2009
7,965
@LAOADAM, I found this, and it seems like you were correct. The relay is for the start capacitor after all. This schematic is for a Dewalt saw but is the same as your B&D when it comes to wiring, they were both made by the same company back then.
 

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Thread Starter

LAOADAM

Joined Nov 21, 2018
273
@LAOADAM, I found this, and it seems like you were correct. The relay is for the start capacitor after all. This schematic is for a Dewalt saw but is the same as your B&D when it comes to wiring, they were both made by the same company back then.
Thank you. this got a lot of help.
can I just keep the capacitor on the line without remove when motor running?
I saw you answered this question, I mean some motor like fan motor has capacitor kept in circuit during motor running. should I use a large capacitor? or should I say how to select a running capacitor?

one more update: the relay used here keep closed when triggered even after the coil power off.
Best
 
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