# Bosch 4100 tablesaw startup issue



## chandler48 (Jun 5, 2017)

It does sound like a bearing seizure, or partial at any rate. You may be able to remove power from the unit, spray PB Blaster in where the bearings are, move the blade by hand a few revolutions and restart it. See if that helps any. Don't get a great deal of overspray in the electrical part of the motor.


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## Gregsoldtruck79 (Dec 21, 2017)

Try one other thing before tearing it apart. Unplug the saw and remove the saw power switch and bypass it by connecting the switch wires together solidly. Stand back and plug it in and see if it acts the same. JMO


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## user97 (Aug 13, 2018)

Thank you both for your input. I'm in the middle of a big move so it will be a few weeks before I can report back with the results.


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## chandler48 (Jun 5, 2017)

We'll be here. Interesting to see how it goes.


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## SeniorSitizen (Sep 10, 2012)

If a saw has never had saw dust removed from the motor, gears, moving parts and switches that's often a good first step. I prefer a shop vac first and compressed air second.


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## user97 (Aug 13, 2018)

So after hot-wiring the on/off switch (function verified, cleaned copper contacts anyway) replacing all 4 bearings (bearing #13 was worn but the other 3 were fine), replacing the motor brushes (they were in near perfect shape) and installing a brand new field coil...the motor still wouldn't run correctly. 

Like before, most of the time the motor wouldn't power up at all. Every once in a while though, with a lot of rumbling and noise, the blade would jump into full speed after about 4 seconds of delay from power-on.

Going over all the pieces I'd worked on, I remembered seeing a tiny circuit board tucked into the top of the black plastic housing around the field coil. Referencing the diagrams, it is marked as the "Speed Governor" (#12, 2610997306) and controls the "soft start" function of the saw. I bought a new board, swapped them out (thanks Bosch for cheaping out with crush-nut connections instead of twist nuts on the already very short wires) and now the saw runs like new!

So hundreds of dollars in parts and new tools for a $40 board.


I hope this info helps others!


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## chandler48 (Jun 5, 2017)

> saw dust removed


Odd you would mention that. I had my Ridgid miter saw and table saw on a jobsite back in September and BOTH died the same day. I was upset to say the least. We finished with another miter saw from the shop and my helpers rinky dink table saw. Took them home and started blowing saw dust from them. Nothing. Finally pulled the triggers and they were caked with saw dust. Good cleaning and they ran perfectly.


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## Nealtw (Jun 22, 2017)

My craftsman RAS stopped on me two times. It has a set of points and some nonsense right in the back of the motor, that helps it decide which direction to turn. The points were burnt one time the next time it was all jammed up with sawdust.


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