WS467 (WS477) - Wall switch
This one is tricky to modify due to the small space available, you have to get the right components. It is a good idea to print out the schematics. Note that this module is made for American, rectangular wall mount boxes and might not fit your local standards.
Recent modules are using a triac called BTA10-600CW which is a 600V, 10A version. This is OK for 220 or 240V usage. Older modules uses a 400V, 10A version called BTA10-400C which gives you very small safety margins on 220V. Worse on 240V! If you have the 400V version, use the idea to put a MOV across the switch, it might improve the reliability especially if you have a 400V triac. Otherwise change the triac to something with a higher voltage rating like 600V. Note that it must have an insulated tab. Since four quadrant DC triggering is used, it is important to look at the DC characteristics of the gate and the Igt. I was lucky and got the 600V version in 8 out 10 of the switches I bought last year :-)
Anyway, all off these modules including the ones with 400V triacs have been working OK for quite some time now but they are also equipped with MOVs. Escept for one of these !@#$%^& spring in one unit. See the FAQ about this.
Triac short form data:
Type BTA10-400C BTA10-600CW
Umax 400V 600V
Imax 10A 10A
Vgt 1.5V 1.5V
Igt 35mA 35ma
Ih 35mA 35ma
Case TO220, insulated tab
Change C1, the big, usually blue, capacitor marked 2E684 from 0.68uF/ 250V to 0.33uF/400V. Check that the height is not more than big electrolytic capacitor in the other corner (around 13mm).
Change C2, the small, usually blue, capacitor marked 2E104 from 01.uF/250V to 0.1uF/400V.
Change R2 from 22 Ohm 1W to 47 Ohm 1W.
I suggest adding a MOV on the board across the terminals where the two incoming wires are soldered as shown on the drawing. Not to the cable for the slave switch if you have a WS477!
If you have a WS477 three-way switch, change also D11 from 1N4004 to 1N4006 or 1N4007. Also change R11 from 10K 1/2W to 22K 1W. A 22k 2W would be safer in case the slave switch got stuck but there is not a lot of space.
I have been using one 0.22uF/400V and one 0.1uF/400V capacitor in parallel to replace C1. The 0.22uf placed in the original mounting holes and the other one, glued upside down in the empty space on the right side of the choke. Don't drill holes there, the house code switch is on the other side of the pcb! One side of the choke is BTW connected to C1 so you can connect on side of the 0.1uF straight to the choke. I drilled a hole close to the hole where the wire from the choke goes in to connect a new wire from the 0.22uF to the other end of the 0.1uF.
Also my C2 was physically too big and I had to mount it on top of the components up in the top left corner. All theses references are as when holding the PCB with components facing you and the choke at the bottom.
I drilled a hole at the triac and placed the new MOV between the triac's T1 and the wire to the choke where the 0.1uf capacitor was connected. Everything was afterwards fixed with epoxy glue.
Local control gives you the possibility to dim the lamp also from the switch. It is strange that they have wasted components to inhibit this feature. It might therefore be a good idea to enable local control before you reassemble the module. Just solder a bridge over the vertical 0.47uF capacitor.