On Wed, 29 Apr 2015 18:24:03 -0400
Bob Engelhardt wrote:

snip
There is a PC board for speed control. No schematic that I could find
on the net.

I had this thought too & I put a Fluke clamp-on true RMS meter between
the controller and the motor. It read the same as the ammeter on the input.

I'm guessing that this is the model you're working on:

http://www.festoolusa.com/power-tool...tractor-583492

Per their website they list the amperage as "Power Consumption
350-1200 watts, 2.9-10.0 amps". Maybe the temperature sensing mechanism
is at fault and not the motor. Just saying...

Interestingly the manual:

http://www.festoolusa.com/media/pdf/...EPA_Manual.pdf

has the amperage as you said:

===
Power consumption (dust extractor only) 2.9 - 8.3 A (350 - 1000 W) see
note 1 .

Note 1: 8.3 A (1000 W) is the medium value for different operation
conditions, a maximum power consumption of 10 A (1200 W) is possible.
===

Different model comparison chart on this page along with amperage
values:

http://www.festoolusa.com/power-tool...st-extractors/

Any loose heat-sink items on the electronics board or something that
could mess up the temperature sensing?

One last thought after perusing the manual... Have you experienced the
unit overheating? From what I could deduce reading the manual:

===
Max. rating of connected Power Tool = 3.7 A - Note: When the suction
power adjuster [1-7] is adjusted to the lowest suction power (see page
10, chapter Settings - Adjusting the suction power) the maximal rating
of a connected power tool can be 9.1 Amps.
===

It doesn't say whether this load is being sensed by the over
temperature alarm but I think it might be. Did your neighbor have
something a bit too greedy plugged into it?

--
Leon Fisk
Grand Rapids MI/Zone 5b
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