Double Socket Fault

LightwaveRF Communi… > Forum > Installation and… > Double Socket Fault > Page 2

This topic contains 25 replies, has 11 voices, and was last updated by  worcell 1 week, 4 days ago.

Viewing 11 posts - 16 through 26 (of 26 total)
  • Author
    Posts
  • #3207
     siddys says:

    siddys
    Participant

    Posted old socket back on Monday, received replacement on Friday, no hassles

    Shame I had to pay return post!

    #3218
     davew21 says:

    davew21
    Participant

    There is in my opinion a major design flaw with the mains sockets and the plug in sockets which is what causes them to keep failing when any type of inductive load is plugged in. I pointed this out to John a while back via email but nothing has come of it, I modify everyone of mine before i fit and since then i have not had one failure, obviously it invalidates the warranty but given the fact that they then don’t fail i really don’t care.

    If anyone wants to know what I did i will tell – it’s very simple but being an electronics engineer by trade obviously makes it easier for me.

    Dave

    #3220
     andytvcams says:

    andytvcams
    Participant
    "davew21":3uvojo86 wrote:

    There is in my opinion a major design flaw with the mains sockets and the plug in sockets which is what causes them to keep failing when any type of inductive load is plugged in. I pointed this out to John a while back via email but nothing has come of it, I modify everyone of mine before i fit and since then i have not had one failure, obviously it invalidates the warranty but given the fact that they then don’t fail i really don’t care.

    If anyone wants to know what I did i will tell – it’s very simple but being an electronics engineer by trade obviously makes it easier for me.

    Dave

    Hi Dave can you PM me your mod.

    Cheers Andy…

    #3224
     petrolhead says:

    petrolhead
    Participant

    Any chance you could send me it too?

    #3226
     davew21 says:

    davew21
    Participant

    To all that have asked about my mod I will gladly pass it on but I’m afraid you will have to wait till the weekend due to work commitments

    Thanks

    Dave

    #3233
     davew21 says:

    davew21
    Participant

    Firstly sorry for the delay in coming back to you all – right here goes.

    The power supply for the electronics in the plug in switches and the mains sockets is the same in both, it’s simply a low value mains rated capacitor in parallel with a resistor off the live, on the end of this is a bridge rectifier, the other input of which goes to the neutral, the r/c network causes the current and voltage to be out of phase so by adding a low value resistor and a zener diode across the output of the bridge along with a smoothing capacitor you have a fairly stable supply, add to this a 3 terminal voltage regulator and another smoothing cap and you have a very stable supply for the electronics that will withstand moderate spikes etc on the mains side without any changes on the low voltage 3.3v side.

    WHY THEN !!!!!!!! do they go and do something stupid like this :-

    the led (leds) that show if the unit is on or off are contolled by presenting a small voltage (3 ish) on pin 13 of the larger IC, they get this voltage by taking the mains output from the relay contact, dividing it down using 2 resistors, 1M and 15K, the 1M goes to the relay contact then the 15K goes from the other end of that down to OV this means when you present 240V AC across both you end up with about 3.5 volts presented across the 15K, this of course is 3.5v ac, i actually can’t remember if they clamp the negative side with a diode (i don’t think they did) but this is where it all goes wrong, there is no control of that voltage what so ever other than the dividing ratio of the 2 resistors, so when you switch off and the relay opens the voltage on the now none mains side of the relay has nothing to clamp it so if you have an inductive load of any sort as the field colapses it can produce a huge spike, the spike of course will enter that resistor dividing network and be reduced by the same proportion as the mains, so a 500v spike (which is not unusual) will end up shoving 6 to 7 volts up that poor IC whose absolute max supply is about 4.5 volts – guess what happens next, yep thats right it doesnt work anymore !!!!!

    If you disconnect (lift) pin 13 from the pcb it doesnt stop the unit working but it does stop the LED changing colour when switching on and off however if after lifting pin 13 from the pcb you connect it to pin 12 it all fucntions normally again because pin 12 is the 3.3 volt output signal that controls the transistor that switches the relay so once again the led changes as it should do.

    I know why they did it like this, it’s because the actual mains being present on the output side of the relay is what causes the led to change state therefore if you tell it to turn off and the relay sticks even though the control signal from the transistor has gone then you can see that there is still mains present even though its supposed to be off however the majority of normal mains sockets don’t have a light to tell you if the switch contacts have welded themselves together do they and too be honest the addition of a couple of extra components would have stopped this problem ever happening, i could have decided how to add these bits but given the lack of room i decided to go down the route described, i’ve added a pic of the board so you can see the parts in question (this is a pre-modded board)

    Please note i take no responsibility for an damage you may do to your own equipment, if you are not comfortable dealing with small electronics then don’t touch it.

    Right then, i hope the above makes sense and i’m sorry if it went on for a while but i wanted to make sure my description not only told you what to do but why it had to be done ![attachment=0:18zcwsk6]double socket.jpg[/attachment:18zcwsk6]

    #3237
     SimonCatlin says:

    SimonCatlin
    Participant

    BLIMEY.

    That is the most detailed post I have ever seen on a technical topic I thought I knew something about (Lightwave, not the PCB/resistor stuff).

    Thanks!
    If there was a Kudos button, I’d have pressed it.

    2 WiFi, 2 sockets, 11 light switches (7 single, 4 double), 2 mood controllers, 1 double wire free switch, 6 plug in on/off, 3 plug in dimmer, 2 PIR, 2 LED, 1 300W Inline relay, 2 signal booster, 1 Energy Monitor and 1 very patient wife. Also Heatmiser's Neo, Ring Bell, Ring Camera, Nest Protect, Canary...
    #3241
     petrolhead says:

    petrolhead
    Participant

    did you recall if the clamped the negative half of the wave? you could stick in a 1N4731A to ground to limit the input to 4.3v. My only concern would be that possibly they are using pin 13 via firmware to not only control the leds, but to monitor the output of the relays for volt drop when turned on to act as a safety trip and by providing a dummy input a safety feature might be being lost. I dont have a double socket at hand to play with at the moment so that is purely guesswork, but I fitted one at a customers house inside an ip66 enclosure replacing the standard 2 gang socket that was in there supplying the pond waterfall pump and lights so this could be worthwhile to prevent problems. What is the 14 pin device, an off the shelf microcontroller or a custom asic?, a datasheet would help work that out, if its meant to be an analogue or digital input.
    Course it would be better if someone from jsjs could comment on this rather than leave us guessing to try to overcome their design flaw.

    #3254
     davew21 says:

    davew21
    Participant

    I don’t think they did which i found suprising, yes i suppose you could shove a zener in there however i just went for the easy option. The way i found out about this was because I killed 2 plug in socket switches within minutes of each other (thought the first one had just failed) so tried a second and that died too, I was switching a flourescent light on with it which had the old style starter and balast in it rather than the new electronic type, can’t say i was too happy about it !!

    The device is an off the shelf micro from some chinese company, data sheet is here if you want to take a look:-

    http://bbs.enroo.com/uploaddir/download … 10P611.pdf

    there’s also a 24LC02 in there as well, just a small eeprom, I very much doubt someone from JSJS would confirm our findings !!

    Dave

    #19120
     Lollettuk says:

    Lollettuk
    Participant

    Hi Dave,

    Any chance you could re-post the DoubleSocket.jpg as it wont allow us to download anymore?

    Thanks!

    LightwaveRF kit: LW500, LW230, LW250, 4xLW220, LW200, 6xLW270, 2xLW260, LW101, LW321, LW600, 3xLW100, LW103, 3xLW107
    #62485
     worcell says:

    worcell
    Participant

    Hi all, Anyone still have a copy of the mod?

Viewing 11 posts - 16 through 26 (of 26 total)

You must be logged in to reply to this topic.