Hello guys,

I think this could be the right forum....

Anyways I have a chop saw that doesn't operate. I pull the trigger system and get nothing no click etc.

I attempted to bypass the switch by connecting the 2 leads going into it and it didn't change anything. I wanted to deduce if the switch was broken and the motor is still operating.

Anyone have any suggestions???? I have included some pics.

Thanks

Kris

It's hard to tell anything from your photos. How many wires go through the switch? Did the saw have an electric brake? You have three wires feeding the saw. The green wire is a ground and should connect directly to the motor frame. The black wire is the one that is usually switched. The white wire can be switched or can go directly to the motor. For the time being forget about the green wire. If you have two wires going to the motor connect them to the black and white wires form the power cord and plug it in. If the motor is ok it will run.If you have more than two wires going to the motor you need to find out which ones are for the brake.Take the switch apart and check out the operation of the contacts. the normally open contacts are probably the the ones feeding the motor run. The others are the brake.

Did you try plugging it into a different outlet or testing the outlet with something else?
Did you check the brushes for wear?

Did you check for 110 at the black and white directly off the cord end, without connecting the wires? Could be a bad plug. if you have power, and bypass the switch, yet the saw still doesn't operate, looks like its time for a new saw (assuming the absence of any OEM safeties)

There is usually 2 switches to get a chop saw to run. Kind of like the thumb and the finger trigger.

Can't tell if your is like mine or not. Mine is a name brand, but I forget which.

Is it plugged in?

Thanks fellas,

I am pretty sure the saw doesn't have a electric brake.

The trigger is a mechanical interference unit when the clearance is available the switch will work.

There are 2 black wires that go to the switch. One comes from the power cord and one comes from the motor housing.

The white is "marreted" and then goes into the motor housing.

I assume I would have to take apart the motor housing to check the brushes??


Tonite I will hook up the volt meter and see if I can get any readings.

When I connected the 2 black leads I didn't get any power. If you zoom in in the first pic you can see where the black leads originate from and in the second you can see where I connected them. If there is 120volts at this conenction point should the motor should fire up??

Thanks again

Kris

If you zoom in in the first pic you can see where the black leads originate from and in the second you can see where I connected them. If there is 120volts at this conenction point should the motor should fire up??

Thanks again

Kris

Absolutely. If you get 120 between the white/black and the point where you connected the 2 blacks bypassing the switch, as long as the wiring isn't broken at the point where it enters the motor housing, it should certainly fire up. The brushes are on the motor... You can access them through the black caps on either side of the motor housing; the ones with the flathead screw slot, which you can see well in pic 1. Just be sure you unplug it first; those brushes pack the same punch as an HEI, trust me, been there, done that!

The brushes are under the two black caps with screwdriver slots.
It's very easy to put in new brushes, pull the cap, pull out the brush and stick a new brush in.

Thanks again guys,

I got a reading of 120 volts on the power cord so there is no problem there. I will examine the brushes next. What signs of wear should I look for?

Thanks

Kris

The brushes will be worn down and be fairly obvious if that's the problem.
Sometimes the get to the point that they're too short to make good contact with the commutator.

I would *guess* they should be about an inch or so long but really you would need to compare them with new ones unless you had a spec sheet.

Might see if you can take a peek at the commutator to see what condition it's in also.

I removed the brush and it is hard to tell how if they are bad. I have the piece here and it one of the corners is worn. The piece is about 5/8 of a inch in length and 5/8 wide 1/4 inch wide.

I took a picture and it didn't come out too well. It was hard to see any details.

I guess I should try to track down a replacement part and see if the saw operates.

I was able to turn the motor over by hand so at least it is not seized...

I will try to take a look at the commutator as well.

if the brushes are shot they rarely just "stop"...you will hear and see the arcing of the now slower turning motor...putt,putt,pop,putt, if you unhook the trigger wires and test them, that will tell you if the other switch is closed and working, if theres no reading find the other switch and jump it, then connect them and plug it in, if it doesnt run, your motor is shot, theres two black leads at the trigger because its a secondary switch and is "inline" on the black lead, quickly (and more safely) test the trigger with an ohmeter and go from there...my guess is it's the primary switch or a shot motor, moneys on shot motor

5/8" doesn't really seem all that short but like I said we don't know how long they were to begin with.

Just like GM starters that need a good whack sometimes when the brushes get too short to make contact with the communtator, I've seen motors have the same symptoms but usually arcing will be noticed first.

Thanks again guys,

I phoned the store I bought the saw from to ask if they had any replacement parts and they don't. So no brushes BUT I "sweet talked" to the lady and she said I could exchange it for a new one. That is great because the unit is about 2 years old and I have also lost the receipt. I didn't think I had any chance of doing that.

It is hard to tell what the length of brushes originally was.

I am heading there Sun so hopefully I can get a new one.

Hello guys,
On Mon night I was able to get a replacement. I thought for sure I wouldn't get a exchange on something but I think they keep the serial numbers in the system.

I measured the brushes in the new one and they are the same size so it was likely not the brushes. I also looked at the assembly diagram and parts list and it contained only one switch. So it could have been a blown motor.

Thanks again

Kris

"The trigger is a mechanical interference unit when the clearance is available the switch will work."...what was all that then?
if the trigger has two black leads, theres another switch of some sort in there, one that has a black, a white, and a green lead

You lucked out :thumbsup:

Just for the record, green is for case bonding, it never goes to the switch and white usually doesn't go to the switch on 120 volt either.

Hello hrd,

What I meant by "The trigger is a mechanical interference unit when the clearance is available the switch will work" is that it was a piece of plastic that when moved out of the way it let the switch operate. It didn't have any electrical connections.