Dewalt Miter saw problem

[73fxe]

I've got a Dewalt 703 compound miter saw that is well used but in good shape, except for the fact it won't run. I have replaced the cord, brushes, and the switch. It was cutting fine but next trigger pull, nothing. Admittedly when I told My Wife what had happened, she said go buy a new saw. I would like to get this one working again if for no other reason that I hate to have something like this die and have no clue why. Thanks

 

[DHCrocks]

check to see that the brushes are free and not getting hung up and not making contact.
are the commutators clean? might have a build up of carbon on them. you can use an eraser to wipe them clean and shiny again or try giving it a shot of contact cleaner and use a swab and spin it by hand.

 

[The Cobbler]

so it ran after you did all that work?
then next time noting?
I'd be looking for a bad connection, a bad switch , etc.
what sort of dignostics have you done, have you checked continuity at the switch, cord etc?

 

[GirlnAgarage]

Is the outlet working?

 

[GirchyGirchy]

I'm assuming these have electronic brakes on them...is it not releasing?

Never mind, sounds like that would be more of a switch problem. Are you positive your wiring is correct?

 

[belvedere]

Do you have a voltmeter? You need to see where you have power and where you don't. For example, if you have power coming into the switch, and it's still there coming out (when switched on), then your switch is good. If you have power going into the motor, then it's a motor fault. Troubleshooting is better than shotgunning.

 

[Rabid Badger]

Do you have a voltmeter? You need to see where you have power and where you don't. For example, if you have power coming into the switch, and it's still there coming out (when switched on), then your switch is good. If you have power going into the motor, then it's a motor fault. Troubleshooting is better than shotgunning.

Poking around inside a partially disassembled tool that is live at mains voltage is a good way to get electrocuted and/or short something out and cause more problems.

Use the continuity setting. Connect one probe to a prong on the plug and check the current path all the way to the commutator. Then connect to the other prong and do the same for that one.

 

[belvedere]

Poking around inside a partially disassembled tool that is live at mains voltage is a good way to get electrocuted

It goes without saying that you “poke around” with the meter probes, not your fingers.

 

[73fxe]

When I got home today I checked the voltage coming into the saw. 0 volts, replaced the cord again , double checked for pinched wires and all is good!!! Thanks to you who responded saves me $250.

 

[belvedere]

Use the continuity setting. Connect one probe to a prong on the plug and check the current path all the way to the commutator. Then connect to the other prong and do the same for that one.

A poor connection can show good continuity with an ohmmeter, but fail with a full current load. I doubt this is the case with the op’s saw, but just something to keep in mind when troubleshooting in general. Using a voltmeter would tell the whole story.

 

[belvedere]

When I got home today I checked the voltage coming into the saw. 0 volts, replaced the cord again , double checked for pinched wires and all is good!!! Thanks to you who responded saves me $250.

Yay, glad to hear that!

 

[Rabid Badger]

It goes without saying that you “poke around” with the meter probes, not your fingers.

There is no reason to probe a live tool when continuity testers exist. Full stop.

Do you also think the best way to find out if a gun has a round chambered is to pull the trigger?

A poor connection can show good continuity with an ohmmeter, but fail with a full current load. I doubt this is the case with the op’s saw, but just something to keep in mind when troubleshooting in general. Using a voltmeter would tell the whole story.

Any such low-current path would literally vaporize the moment he pulled the trigger after reassembling the saw.

 

[belvedere]

There is no reason to probe a live tool when continuity testers exist. Full stop.

Do you also think the best way to find out if a gun has a round chambered is to pull the trigger?


Any such low-current path would literally vaporize the moment he pulled the trigger after reassembling the saw.

You would be doing the readers of this thread a favor if you kept your "tech tips" to yourself. I have 25 years experience as an electronics tech. The only thing "vaporizing" is whatever you're smoking.

 

[Rabid Badger]

You would be doing the readers of this thread a favor if you kept your "tech tips" to yourself. I have 25 years experience as an electronics tech. The only thing "vaporizing" is whatever you're smoking.

25 years and you never learned what 15+ amps does to a broken wire?

 

[rharman]

Is the outlet working?

 

[belvedere]

25 years and you never learned what 15+ amps does to a broken wire?

There are infinite "in between" states of high resistance. It isn't a case of perfect continuity or "broken wire". There are many cases of higher than normal resistance that will read fine with an ohmmeter (which uses very low current) but will not properly conduct several amps, for example. Picture an 18 or 20 gauge wire. It would read perfect continuity with the ohmmeter you advocate using, yet would quickly heat up with sufficient current, causing a voltage drop (not "vaporize"). That's why we measure voltage drops to troubleshoot in the real world. Hopefully that helps clear it up for you, but if you have other questions, feel free to ask.

 

[Rabid Badger]

There are infinite "in between" states of high resistance. It isn't a case of perfect continuity or "broken wire". There are many cases of higher than normal resistance that will read fine with an ohmmeter (which uses very low current) but will not properly conduct several amps, for example. Picture an 18 or 20 gauge wire. It would read perfect continuity with the ohmmeter you advocate using, yet would quickly heat up with sufficient current, causing a voltage drop (not "vaporize"). That's why we measure voltage drops to troubleshoot in the real world. Hopefully that helps clear it up for you, but if you have other questions, feel free to ask.

In something as dead simple as a miter saw? It's a power cord, snap action switch and a brushed universal motor.

Also, you clearly didn't pay attention to the symptoms. It wasn't running slow. It wasn't running intermittently. It was dead.

Where in your *25 years of experience* did you learn to completely disregard the failure mode of the device you're working on?

Also, what did the problem turn out to be?

Hint: It wasn't a high-resistance connection.

Stop giving dangerous advice.

 

[belvedere]

Stop giving dangerous advice.

You are aware that thousands of people use voltmeters on 120VAC circuits and devices everyday, right? Yet you maintain that using a voltmeter is dangerous? Well, in that case, then yes, you should probably stay away from troubleshooting electrical devices. However, the rest of us are trying to hold a rational conversation, so please keep your ignorant drama to yourself. Thank you.

 

[belvedere]

Also, what did the problem turn out to be?

Hint: It wasn't a high-resistance connection.

Right, but nobody knew what the problem was at first, did they? He had to...troubleshoot it. What did he use to do so?

Hint: it was a voltmeter. You know, that oh-so-dangerous device that no one should dare touch.

 

[Wamsutta]

When I got home today I checked the voltage coming into the saw. 0 volts, replaced the cord again , double checked for pinched wires and all is good!!! Thanks to you who responded saves me $250.

So does that mean the first cord you installed was no good?

 

[Retroman]

I have had that exact problem when I want a new tool!!

 

[Aileron]

Christ sakes , reading a few replies to this post , you would think the op was trying to diffuse a live bomb.

 

[GirlnAgarage]

Just covering all bases. I've done some boned-headed stuff.