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Thread: Dead table saw?

  1. #21
    Join Date
    Jun 2007
    Posts
    74

    Default Re: Dead table saw?

    I'm sorry I never posted anything else, but basically I was watching and waiting to see what was going to happen, and just never came back.
    Except for the fact that my saw is the "homeowner" type, your problem sounds a lot like mine! So here's what ultimately happened. Since changing the capacitor didn't change anything, and since the saw would run sometimes after I oiled the motor shaft really good, I just continued to turn it on every so often. Every 15 minutes, 30 minutes, a few hours, or whenever I was in the workshop. I also oiled it more, probably too much. Sometimes it ran, sometimes it didn't. It finally got to where it ran every time. I have to assume that the motor really, really, really needed oil! Like I said before, I never knew whether I was supposed to oil it or not, and I didn't want to screw anything up, so I would just oil it a tiny bit every now and then. I feel kinda bad that Jim DeLaney put all that effort into my problem, when it was nothing but lack of oil, but I just didn't know any better. (Also, like you, I felt that everything was turning okay by hand.) But since it started running again, I've built a fence with it, and it hasn't missed a beat! So thanks again, Jim D!

  2. #22
    Join Date
    Feb 2008
    Posts
    19

    Default Re: Dead table saw?

    well when all has failed try to see if you have a bad start capicator. like someone else mentioned above. Usually when you have a bad start cap one hears hum followed by slow rotation. A fluke meter can measure the cap for you. If you don't have fluke meter. Just use an analog meter and observe the swing of the needle.

  3. #23
    Join Date
    Feb 2008
    Posts
    19

    Default Re: Dead table saw?

    lubrication ports are very important on the older units. They incorporate felt pads in the motor to hold the oil. Perdoic lubrication with a turbine oil should do well.

  4. #24

    Default Re: Dead table saw?

    Here is the deal on my Sears model 113.298051 direct drive 10" table saw that I bought new back about 1985 or so. First some background. I am on the third stator for the motor, the second capacitor, and I have used up two starter relays so should be on my third...but I have a better idea. Stay with me on this as I have the problem solved permanently. As with others here on the forum, the motor sometimes runs normally and other times it would seem to grind along at a low speed with a lot of vibration and shuddering or even running at high speed with lots of vibration and shuddering and of course always smoking until all was quiet.

    Some parts review are in order. In the switch box there is a thermally activated circuit breaker, a 108-130 mfd capacitor, and a Klixon 3CR-718-193 starting relay which is pn 62453 in the parts list for my model on http://www.searspartsdirect.com . Info on the 3CR family of relays can be found at http://www.firsttech.co.uk/files/3cr.pdf and it is a 100 series with a Klixon rating no. 193 in the chart on page 2. The top "line" in the diagram is the white wire in the switch box. The capacitor, if it is bad (go here to see how to test it: http://www.wikihow.com/Check-a-Start-Capacitor ), can be replaced for under 5 dollars at Graingers and it is Grainger pn 4X058.

    The thermally activited circuit breaker, if it needs to be reset, must be allowed to cool, sometimes for as long as 20 minutes. It is hard to tell if it has popped out. If the saw does not work at all, this might be the problem and resetting it should cure the problem. After allowing for cooling, it needs to be pressed in pretty hard. If it does not need to be reset, then pressing it in will do nothing for you. You will be pressing all day. However, if it does need to be reset, when pressing it hard will be felt a little bit of inward movement concurrent with a nice snapping sound indicating that the CB has reset. Moving on.....

    The way the starting relay is supposed to work is that it is to provide current to the start winding in the stator of the motor at the same time the normal run windings are provided current but it SHOULD only do this for a short instant. When the saw is first switched on, there is a tremendous inrush of current into the normal run windings. The starting relay is set to recognize when the inrush current exceeds 30.30 amps (this value taken from the second www link above) and when it does, the starting relay contactors SHOULD close which now allows current to flow through the capacitor and into the start winding in the stator. This start winding is wound differently through the stator than the run winding. This difference in how the start winding is wound allows the motor to accelerate whereas how the the run winding is wound merely allows the motor to run at a constant speed. If one tries to start the motor without the start winding helping, then the motor will turn at a very slow speed (due to no acceleration due to the inoperative start winding) and overheat with lots of humming and then some smoke, probably a popped CB, and all will be quiet. Anyway, if things are working normally, after the large initial inrush of current, the current through the run winding drops down to a more normal value as the saw comes up to speed. As the current falls below the cutout value of 25.10 amps, the starting relay contactors SHOULD open which will stop any current from flowing through the capacitor and into the starting winding in the stator. It appears to me that a bad capacitor (usually shorted out internally) will allow a large flow of current through it which will cause the contactors inside the starting relay to go bad by welding shut. This, in turn, will cause the starting relay to not release as it should (as the contacts are welded shut!) and even after the motor is running at normal speed, it is still getting current through the capacitor and into the start winding. I ran some tests using jumper leads and the symptoms of this are normal run speed with a lot of vibration and a smell of smoke with actual smoke coming from the motor after about 60-90 seconds of run time. It is the vibration that you will notice though!

    So it appears that the fix is to get a new starting relay and a new capacitor. But I have bought two relays so far and need a third. Maybe I can try another trick. If all that the starting relay does is provides current to the start winding on acceleration, and if I have determined that my conactors are welded shut preventing automatic cutout of the start winding, then if I do the cutout of the current to the start winding manually, I will achieve the same goal. My fix is to have a spring loaded toggle/pushbutton switch inserted between the starting relay and the new capacitor. In my saw, this is a short black wire that is about 3" long. To start the saw, I hold the toggle against the spring and then flip the main switch to on. As the saw comes up to speed, I release the toggle/pushbutton. Doing so, positively disconnects the start winding from any current and will save your motor! I have read on these forums about some saw owners having intermittent starting relay action. This fix will still work in that case.

    You would need to do away completely with the starting relay if you think it has failed open. This would be characterised by the motor running slowly at startup and never accelerating (once you know the capacitor tests good). My suggestion would be to use a hefty toggle switch with two poles that would allow "off-on-momentary on" action. The white wire would run straight through the switchbox and on to the motor with a tail coming off of it in the switchbox that would connect via the "momentary on" contactors on the "right" side of the switch to the capacitor and on to the red lead of the motor. The black wire coming in from the wallplug would connect through the "left" side of the switch's "off-on" contactors, through the circuit breaker, and on to the black lead of the motor.

    It appears that others are looking for a "normal" wiring diagram for the direct drive saws made by Sears. I can be fairly confident that they are all wired the same. Since I can't post a diagram here, I think I can do an adequate job of verbally describing the wiring. If you look at your starting relay, notice that there are numbers cast into the plastic next to each of the terminal spade connectors. Orient it so that the 1 is lower right and the 3 is upper left. Coming in from the wallplug are the normal three wires carrying the 120V juice. The green goes off fairly quickly to ground the entire machine so we won't worry about it too much more. The white wire gets connected to terminal 2 while the black goes into the switch, comes out the other side of the switch, goes through the circuit breaker, and then connects to the double spade terminal at 3. Another black wire runs off of the other spade at terminal 3 and goes out to the motor. A white wire runs off of 5 and goes out to the motor. Notice that the coil of the starting relay made of copper wire connects between terminals 2 and 5. It is easy to see here how the run winding of the stator gets its electricity the entire time the switch is on. Terminal 1 connects to either post of the capacitor through the short black wire and then out of the capacitor's other post through the red wire that goes to the start winding of the stator. It is when a tremendous inrush of current (exceeding 30.30 amps) passes through the coil between terminals 2 and 5, that terminals 2 and 1 connect inside the starting relay allowing the start winding to receive current through the short black wire, through the capacitor, and on through the red wire that goes to the stator of the motor.

    I hope this helps. I can be reached at bobka at charter dot net .

  5. #25
    Join Date
    May 2008
    Location
    Pacific Northwet
    Posts
    1,418

    Default Re: Dead table saw?

    Looking at the exploded diagram of the motor & control box, there is a capacitor (item 17) in the control box. That indicates that this is a brushless, "capacitor-start, induction-run" motor.

    If you take the whole motor/control box assembly to a motor repair shop, along with the diagram & parts list, they can probably diagnose it for you.

    As for getting at the motor, it appears that you have to start by removing the front panel (where the height adjuster is). See the "unit housing" diagram. Unfortunately, it appears to be the sort of thing that's built around the motor and requires nearly disassembling the whole shebang, just like you have to remove the pins out of the cylinder in the lock of the trunk lid in order to replace the heater core on a 1984 Plymouth Reliant K.

  6. #26
    Join Date
    Mar 2010
    Posts
    1

    Default Re: Dead table saw?

    First, let me say thank you to flitzerfalke - your post was extremely helpful in getting my table saw up and running. However, there was one fact that you overlooked in your post - which as it turns out is key.

    For anyone facing the challenge of rewiring from scratch it is imperative that you mount the starter relay correctly because it is a gravity dependent unit. The end with the number 3 and 5 is the top and it must be mounted or secured so that that end of the unit is on top.

    After correctly wiring according to flitzerfalke specs, and assuring that the starter relay was oriented correctly, my craftsman 10" table saw model number 113.295820 is now up and running perfectly.

    Thanks guys! You saved me hundreds of dollars and kept one more good table saw out of the landfill!

  7. #27
    Join Date
    Aug 2011
    Posts
    1

    Default Re: Dead table saw?

    My was is a model 113.197752 radial arm that runs backward really slowly then trips internal breaker.

  8. #28
    Join Date
    Sep 2012
    Posts
    1

    Smile Re: Dead table saw?

    While this might be dated since the table saw 113.298051 appears to be considered obsolete I wanted to post this info for other owners:
    The motor starter no longer available through Sears is available through a great supplier named Arrowhead Electric Company, Santa Fe Springs, CA 90670-5265. Phone # 562-921-8521
    After considerable cross referencing the various manufacturers and part numbers we found the exact replacement which is
    Model # 3CR-118-193. If you also need a replacement Capacitor, Arrowhead has that also.. "Packard Motor Start Capacitor PMJ108"
    Arrowhead Electronics were super to work with and they sent the parts out in a weeks time. I would do business with them again for certain!. :)

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