Component Identification "Valdex TB 10" three lead capacitor wired to ground? - Page 1
Forum section: electronics / repair

author: ghorizo
author_rank: Contributor
timestamp: June 25, 2023, 09:09:42 pm
content: Hello I am having trouble identifying this component found in the motor wiring of an old sewing machine.Since it's wired across the phases leads me to believe it's a capacitor, on the side I'm holding it from there was another red lead which has been blown away with some potting, but I'm puzzled by the third lead wired to the chassis: which seems to be non-conductive thanks to the paint and has no evident grounding point.The rightmost pair of terminals is the mains input, left to that is a plug for a lamp and from there depart the two leads to the TB 10.The large ceramic resistor measures 20 ohms and is wired in parallel to a phase so that it contacts first when the switch is lightly activated, applying further force the other contact is made. I believe it's to provide a soft start?Any help to get this thing running again would be much appreciated!Btw the motor is 220v 1.5A.

author: fzabkar
author_rank: Super Contributor
timestamp: June 25, 2023, 09:44:14 pm
content: http://asagaya-chinpindo.com/DSCN5640.JPGhttp://asagaya-chinpindo.com/DSCN5642.JPGhttp://asagaya-chinpindo.com/tokkahannbai2020.htmlValdex is a French manufacturer of capacitors.I would think that removing TB10 should not affect the operation of the machine.

author: ghorizo
author_rank: Contributor
timestamp: June 25, 2023, 11:17:54 pm
content: Thanks! Could not get any results searching in English.So you think it's just to suppress some noise from the motor? Any idea on the third lead?

author: fzabkar
author_rank: Super Contributor
timestamp: June 26, 2023, 12:21:54 am
content: I would think there would be two class-Y capacitors plus an earth wire, even though the grounding appears to have been poorly implemented.

author: ghorizo
author_rank: Contributor
timestamp: June 26, 2023, 04:41:40 pm
content: you mean inside the TB 10 there would be two capacitors?

author: fzabkar
author_rank: Super Contributor
timestamp: June 26, 2023, 05:02:56 pm
content: Quote from: ghorizo on June 26, 2023, 04:41:40 pmYes, I believe so.... or more probably something like this:https://ae01.alicdn.com/kf/S860911157c9d4ccc85807e91f99392252/2PCS-X-AD-MXY-TYPE-X2Y2-0-22UF-X2K-2-X-2200PF-Y2M-X2Y2-0-33UF.jpg

author: floobydust
author_rank: Super Contributor
timestamp: June 26, 2023, 05:52:22 pm
content: Yes it's a paper/wax dual capacitor but they are uncommon nowadays, you would use two safety-certified Y-class capacitors with the common ground.Sewing machines caused AM radio interference which was not wanted. Arcing across the motor brushes and the speed control switches.I would guess they are large around 47nF each and 300VAC rated but I can't see the schematic for this box. There should be another capacitor across the motor terminals.Don't use Rifa PME271Y they are known unreliable. Kemet PME850 series looks good to me.Those Aliexpress filters are eh ur uh have a lot of capacitance and dubious quality given there is no fuse to be seen it makes me not want to use them.

author: factory
author_rank: Super Contributor
timestamp: June 26, 2023, 06:29:39 pm
content: Mains delta filter/suppressor, containing both class X & Y capacitors, LCR components make them in a radial wire ended package, but I'm struggling to find a stockist now, I last bought some about 10 years ago.https://lcrcapacitors.co.uk/wp-content/uploads/delta-filters.pdfDavid

author: ghorizo
author_rank: Contributor
timestamp: June 27, 2023, 11:43:27 am
content: Thanks for the replies guys, helping me figure this out!This 2in1 cap story had me intrigued so yeah upon closer dissection I can confirm it being a capacitor, yayThe potting has gone sticky, hiding behind we find the rolled up foil alongside the insulating paper and sure thing it's waxy and sticky!c1.jpgFurther unrolling we first see the first external section being shorter and connected to ground. So this would be the Y capacitor paired with the ground right?c2.jpgAnd after that we uncover the failure point, where the foil has burnt to ashes!c3.jpgAnd at the end the two contacts where the wires were connected constituting the X cap.c4.jpgSo length for the Y section is about 150 cm and for the X 14.5 cm with a width of 2 cm. I would try to calculate the capacitance but my calipers are not precise enough.Ok now I go wash my hands they are still sticky and sort of itchy.