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Author Topic: CT Shuts off Randomly in Auto Mode  (Read 957 times)

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Offline Chris Wong

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CT Shuts off Randomly in Auto Mode
« on: June 13, 2020, 10:58 AM »
My CT 26 shuts off seemingly randomly when in Auto mode.Sometimes it shuts off after 30 minutes of continuous use, and other times, it will run for two hours continuously other times.

I don’t think it’s due to overheating, since when it shuts off, I can immediately switch it to Manual and it runs. This has been going on intermittently for about six months. TheCT lives in my shop where power is consistent and it doesn’t get very hot. I have replaced the main filter hoping that would help but it hasn’t made a difference. The tools plunged into the front of the CT continues to operate after the CT shuts itself off.

Any ideas where the problem might be, or what I could try replacing? The unit is well out of warranty.
Chris Wong, http://FlairWoodworks.com
First Festool was a free pencil.
Shipping live-edge cribbage boards around the world since 2010.

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Offline Alex

  • Posts: 7351
Re: CT Shuts off Randomly in Auto Mode
« Reply #1 on: June 13, 2020, 12:30 PM »
There is only one part in the vac that regulates this behaviour and that's the electronics board 202317.

The way how it happens intermittently makes me think it is a single capacitor on the board that's on the edge of breaking. But unless you know how to check this your only option is to replace the entire board for $116 ex. vat.

Offline Chris Wong

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Re: CT Shuts off Randomly in Auto Mode
« Reply #2 on: June 14, 2020, 12:23 AM »
Thanks, Alex. I appreciate your depth of knowledge.
Chris Wong, http://FlairWoodworks.com
First Festool was a free pencil.
Shipping live-edge cribbage boards around the world since 2010.

Offline Laminator

  • Posts: 359
Re: CT Shuts off Randomly in Auto Mode
« Reply #3 on: June 14, 2020, 10:22 PM »
My ct26 did that for a couple of years at total random. The tool continued to work but the vac shut off.  At first switching to manuel and back to auto worked to get it going again.  It finally got so bad and also I noticed the vac slowing down but would regain the speed if I wiggled the vs knob.  I opened the cover to the controller board and it was covered with dust (vac is 6 yr old). I gave it a thorough cleaning with a blow gun and it hasn't missed a beat since going on 5 months. Hope this helps.

Offline Chris Wong

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Re: CT Shuts off Randomly in Auto Mode
« Reply #4 on: June 14, 2020, 11:38 PM »
@Laminator Worth a try! Which cover did you open? The one next to the switches?
Chris Wong, http://FlairWoodworks.com
First Festool was a free pencil.
Shipping live-edge cribbage boards around the world since 2010.

Offline jimmyboygr

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Re: CT Shuts off Randomly in Auto Mode
« Reply #5 on: June 15, 2020, 07:10 AM »
Are you using brushless motor sander with it?or it gets too hot/environment?
**It is legally prescribed for a "safety inspection in accordance with employer's liability association DGUV regulations 3+4 and Guideline DIN VDE 0701/0702" to be carried out each time the housing is opened. This can only be done by a specially trained electrical engineer. In many cases, special tools are also needed to ensure proper repair.

Please note that all guarantee and warranty claims shall be rendered void as soon as any unauthorised repair attempts are carried out.

We explicitly advise you not to carry out your own repairs.

Offline Chris Wong

  • Festool Dealer
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  • Posts: 945
  • I make things that challenge me.
    • Flair Woodworks
Re: CT Shuts off Randomly in Auto Mode
« Reply #6 on: June 15, 2020, 10:08 AM »
When it shuts off, I’m using a router. I do use a Mirka CEROS with the CT at other times.
Chris Wong, http://FlairWoodworks.com
First Festool was a free pencil.
Shipping live-edge cribbage boards around the world since 2010.

Offline Laminator

  • Posts: 359
Re: CT Shuts off Randomly in Auto Mode
« Reply #7 on: June 15, 2020, 10:37 AM »
Chris, I removed (by memory) 4  or 6 screws that allows the entire front, outlet and all to lifted. Wires to the outlet have to unclip and i can't remember if other wires had to unclip or not.  One caution, if you move the sockets where the on/off switch and the speed control connect (I rotated them while blowing) they must go back exactly to the original position for the switch to function properly. It took 30 minutes of trial and error to get it back to normal lol. It has performed flawless ever since.

Offline jimmyboygr

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Re: CT Shuts off Randomly in Auto Mode
« Reply #8 on: June 16, 2020, 02:30 AM »
The reason I ask is that the ct on auto function when connected to a low amp draw machine,it sometimes isnt enough to wake up the vacuum.If it shuts off after some use,you could also check the thermal sensor.It is a cable that starts from the electronics and ends in the motor housing as gold pin.Also If the brushes generate more sparking than normal,it could increase the heat in there.Also check the cable for cut spot,maybe twisting it a bit shuts the ct off. [eek]
**It is legally prescribed for a "safety inspection in accordance with employer's liability association DGUV regulations 3+4 and Guideline DIN VDE 0701/0702" to be carried out each time the housing is opened. This can only be done by a specially trained electrical engineer. In many cases, special tools are also needed to ensure proper repair.

Please note that all guarantee and warranty claims shall be rendered void as soon as any unauthorised repair attempts are carried out.

We explicitly advise you not to carry out your own repairs.