My craftsman circular saw stopped working is there some switch safety issue
There are three possibilities, listed below in order of probability.
1. Bad power cord or broken plug
2. Dirty or burned-out switch contacts
3. Bad motor brushes or other broken internal connection
First, inspect the power cord, especially at the plug. If the blades on the plug are heavily tarnished, polish them to ensure a good connection. If you are in the habit of disconnecting by yanking on the cord instead of pulling on the plug to remove it from the outlet, the problem is very likely a broken wire right at the plug. Have a helper hold the saw with the trigger on while you manipulate the cord at the plug. If the saw starts at all, you'll need to replace the plug.
If this doesn't work, the fault is at the saw itself. Unplug the saw and remove the cover (you will probably have to remove the blade to get at some of the screws). Use the resistance range on a multimeter to check for continuity across the switch while it is on. If the resistance is more than a couple of tenths of an ohm higher than that of the test leads connected directly together, the switch contacts are not in good condition. Check for continuity between the hot terminal of the switch and the hot prong on the plug, and between the neutral (white) wire to the motor and the neutral prong on the plug. Also, if you have a three-wire cord, check for continuity of the ground (green) wire from the case of the saw to the ground pin on the plug (the saw will work with this open, but you lose the safety protection of the ground wire if it is open).
If all of these check out, then you'll need to check the motor. First, look for a resettable breaker or thermal protector on the motor. This will be a short plastic rod or button (red, black or white color) on the brush end of the motor, if present. Push it in - if it clicks on the way in, it was tripped. Next, do a resistance check on the motor. You should have a low resistance from the switch to the neutral wire (i. e., through the motor). If it is much more than a few ohms, remove the brushes and clean the commutator with a cotton swab soaked in isopropyl alcohol. Inspect the brushes - if they are broken or severely worn, replace them. Recheck the motor continuity after you put the brushes back in. If your first continuity check showed an open circuit and it still reads open, you may have a tripped or blow thermal protector in the motor (some internal thermal protectors are buried in the winding and can only be replaced by having the motor rewound).
Carefully check all electric connections before reassembling, and make sure no wires are pinched by case parts or the switch mechanism. Reassemble the saw completely before applying power.
Apr 10, 2014 |