PM66 motor issues

[Aaron J Johnson]

I have a PoweMatic 66 cabinet saw. We used it one day to make a ton of cuts for shoulder joints. When almost done, and after a small rest (while we assembled the boards), I needed two more cuts. Tried cutting on the PM66 but it wouldn't come to operating RPM needed. It does start. I pulled it apart, cleaned out lots of sawdust (some discolored) and tried again with same result. Tested the two capacitors and replaced one. Tried again, same result. Read on some posts but not tracking. One said to check the starter switch one one end, but mine has an external start switch with push button stop. What am I not getting and what should I do next? I'm well beyond my capabilities.

[John TenEyck]

There is a centrifugal switch inside one end of the motor. It's likely jambed up with sawdust and won't disengage as it's supposed to and that will prevent the motor from attaining full speed. Pull the motor out and either clean it out yourself or take it to a motor shop and have them go over the motor. If you choose the later route, it would be a good idea to have them replace the bearings and capacitors, too. For about $150 you'll have a motor good for another 25 years.

John

[Aaron J Johnson]

There is a centrifugal switch inside one end of the motor. It's likely jambed up with sawdust and won't disengage as it's supposed to and that will prevent the motor from attaining full speed. Pull the motor out and either clean it out yourself or take it to a motor shop and have them go over the motor. If you choose the later route, it would be a good idea to have them replace the bearings and capacitors, too. For about $150 you'll have a motor good for another 25 years.

John

Thanks John! I pulled it apart (for the second time and think I found the problem...well two actually. One of the female blade connectors had some sawdust in it. But the biggest issue might be mis wired caps and switch. I was careful in taking pic and watching wiring but clearly missed the fact that one wire to the switch was not even fed into the cap box.

Does anyone have a diagram that shows how the caps and switch are wired?

[Aaron J Johnson]

John - Can you (or someone) confirm that what I have pictured in the attached photo is the switch in question?

448548

[Alex Zeller]

Yes, that's the switch for the starting capacitor (not to be confused with the run capacitor). It makes contact when the motor isn't running so the starting cap is part of the motor. Once the motor turns fast enough centrifugal force opens the switch removing the starting capacitor from the circuit. It's not too unusual for sawdust and small wood chips to get caught up in it. Normally I see just the opposite than what you had. Chips enter when the motor is running and prevents the switch from closing when the motor is shut off. The next time it gets turned on the motor wont spin, it just hums.

[Marc Fenneuff]

There should be instructions under the capacitor cover showing the wiring. I would check the switch, however. I bought a gently-used 2001 PM66 this past summer and after doing some refurbishment of the arbor bearings, the saw would start but not run at full speed. I too replaced both capacitors, and disassembled the motor to look for problems, but noticed an arc occurring behind the switch at startup that did not look safe. It turned out that one of the leads was not securely screwed into the terminals on the switch. Problem solved, for me. That was unexpected but a happy result.

[John TenEyck]

Thanks John! I pulled it apart (for the second time and think I found the problem...well two actually. One of the female blade connectors had some sawdust in it. But the biggest issue might be mis wired caps and switch. I was careful in taking pic and watching wiring but clearly missed the fact that one wire to the switch was not even fed into the cap box.

Does anyone have a diagram that shows how the caps and switch are wired?

OWWM.org should have the info you need. But if you've got the motor out you might better take it to a motor shop and have them go over it. New bearings, new capacitors, cleaned and ready for another 30 years. Chances are you'll never have to think about it again.

John

[Aaron J Johnson]

Thanks all for your help. Your advice really hit home and tomorrow the motor goes to the shop for a once over.

Also, thank you for not peppering me with comments about this being solved before. I have been on forums where it is hard for neophytes like myself to ask questions. I read those threads, but didn't understand. You all helped me understand. Thank you!!!