Festool CT Midi vacuum repair? - Page 1
Forum section: electronics / repair

author: artv
author_rank: Contributor
timestamp: May 06, 2025, 04:00:50 pm
content: HiI have a 15 year old Festool CT Midi vacuum that's worked flawlessly. Suddenly the vacuum doesn't turn on - I get nothing. I've checked and there's 240V coming in.I've also checked the motor brushes and there's loads of wear left.Here's a link to the parts diagram - all bits are available from Festool so really want to fix it myself:https://www.mtmc.co.uk/Festool-CTL-MIDI-GB-230V-/-494109-Spare-Parts__p-171330.aspx?srsltid=AfmBOopD_n6X23jO1kLxwl8Bz0JrmCO3AM3yLfT1CRdy2dfkO1Y4nTGkThere's also a wiring diagram attached.Any ideas how I can diagnose issue - parts look easy to replace. I did wonder about the switch - it has off, on and auto mode which comes off with the AC power tool take off. Should this have 240V coming through?The AC power tool take off works ok.Any help at all greatly appreciated!Thank you.

author: Poroit
author_rank: Frequent Contributor
timestamp: May 07, 2025, 09:34:00 am
content: G'day artv,What is your Electrical background like?Do you have any experience working on 230V appliance with a multimeter?

author: artv
author_rank: Contributor
timestamp: May 07, 2025, 09:35:59 am
content: Hi PoroitIt's limited but happy to learn!Cheers

author: Poroit
author_rank: Frequent Contributor
timestamp: May 08, 2025, 08:02:19 am
content: Be aware that this Voltage is leathal!!Is your workshop fitted with RCD's ?Do you understand the wiring terms Active, Neutral and Earth?Have you got a decent multimeter with test leads?https://www.digikey.com.au/en/blog/what-are-multimeter-cat-safety-ratings?srsltid=AfmBOopjNMzdTscOsE_A096YewYF1OPh3qnMX_1DQHkY-oIetSxNw66B

author: benj38
author_rank: Frequent Contributor
timestamp: May 09, 2025, 01:04:51 pm
content: First, you say that there is 240V coming in. You mean to the points marked "1" and "2" in the diagram?Quite often the problem is an intermittent connection where the power cable enters the plug or when it inters the instrument. Verify that this is not the case by non-violently bending and twisting these points on the cable while the power is on to see if you get some bursts of life from the machine.I would then start by checking continuity of wires in the ohms or continuity ("beep") mode of the multimeter, withno powerapplied!Much safer for a beginner, and works very well in most cases.Basically, the neutral and phase wires from the wall plug (wires A and B in your diagram) should end up with a continuity connection (I would say max an ohm or two on the multi-meter in the ohms mode) to the two motor wires (labeled H in the diagram), when the switch is on.In other words, wire A should ultimately connect to one of the motor wires, and wire B to the other motor wire.I am assuming here that there is no electronic circuit board inside this instrument. If there is such a board then the connection will not be direct but through some electronic component or a relay, which would be harder for you to diagnose.Start tracing each of the motor wires backward towards the supply wires A and B, until you find some connector or switch, etc. where the wire goes into but you get no continuity between that wire and the wire going out of that connection or component. This will most probably be your faulty part.If you report what you find following this process we can try to further assist.