Modifying the Wall Switch
The problem: If you open a switch you will find a small piece of springy metal attached to a plastic plunger. When you press the button, that metal piece shorts a set of contacts on the circuit board. Unfortunately that piece of metal is only attached by a blob of melted plastic and maybe a little glue. After repeated use the metal breaks off. If you have a switch that works from another controller but not by its own push button, this is probably the cause. If your switch has local dimming enabled (explained later), this failure will cause the light to continuously cycle from bright to dim and back.
The metal piece can be completely removed and a new surface mount switch soldered directly to the circuit board. There are a number of switches that will fit in the space. Many of the electronics catalogs such as Digikey carry them. I chose part number PB-73 from All Electronics ). Either the switch or the circuit board must be modified slightly for this to fit. I chose to modify the switch because it's quicker. Simply cut off two of the switch leads diagonal from each other then solder the remaining leads to the contacts on the circuit board. Your may need to use a knife to remove what's left of the nub on the end of the plastic plunger so it doesn't stick down too far. After everything is assembled you will have a wall switch with a light touch and a nice tactile feel.
The slide switch below the push button is intended to cut all power to the light when you change the bulb. But they always seem to get slid over to the off position and since most of us change a light bulb occasionally with the power on anyway, you might want to disable it.
Soldering a jumper between the contacts. This will will additionally save you from having to reinstall the little metal contact that activates it.
module that randomly turns on
The WS467 wall switch (and I suspect it's variations, as well) does indeed "randomly" turn on.
Specifically, under the correct conditions, a WS467 can "glitch" on due to a power spike from a large bank of magnetic ballast fluorescents on the same circuit, large motor, etc. And filter caps across the 78566 chip, resistor change in the "button" line nor MOVs do not help.
The solution is actually quite simple, once it is figured out. The 78566 chip in the WS467 contains 2 unused pins (pin #8 and pin #9) who's function is unknown to me. However, manipulation of pin #9 can cause the WS467 to turn on the light.
After discovering this, I have since tied pin #9 to -v and the "random" light turnons have stopped. My personal preference is to install a 10K 1/8-1/4w resistor across the top of the ic between pin #9 and pin #18. A hard wire will probably be ok, but not acceptable standard practice when dealing with bidirectional I/O pins.
In most cases, the failure was in a high wattage resistor near the 'bottom' of the module. Look at how a wall switch is normally mounted inside a wall box. Call the part closest to the floor the 'bottom'. When you disassemble the wall switch, look for a 1/2 watt ~68Ohm resistor near the bottom of the module. If it has a brown crack on it, you know that you have located the overheated/dead part. Replace it with a 1 watt unit.
Another component prone to failure is
the triac. You can replace the triac with a new triac. For 110v modules RadioShack RS # 276-1000. That's also an NTE #5645
Here is a sure cure for 3 ways working only from the master switch or just OFF from the remote switch
1. First try switching the connection between the blue and the black wires. There is a report that this may solve the problem. If it doesn't read on.
2. If you can, connect both the slave and master to the 'hot' line wires, not in series with each other as suggested in the WS4777 instructions. If this doesn't solve the problem, read on.
3. This solution requires replacing a resistor inside the master switch. The little theory behind it: the signal strength from the slave switch is attenuated by the resistance of the wall wires and the resistance of the lamp filament (the X10 signal passes through the lamp). Thus with long wires, and some hot lamps, there is insufficient signal to detect remote switching. This resistance is added to a resistance of an INTERNAL resistor inside the switch. My solution was to reduce the internal resistor, such that the total resistance (wall wires + fillament + internal resistor) is reduced, increasing signal strength.
Sometimes the problem has an even weirder manifestation: the slave switch can turn the light OFF but not ON. This is related to another parameter: the X10 transmission protocol. Turning ON requires more '1' bits than OFF. '1' bits are higher voltage, which as discussed, are attenuated. OFF is the absence of voltage, which is there by default. Thus OFF works but ON doesn't.
Yet other times, the opposite happens: the wall switch turns on but not off. The wall switch module is wired in series with the light bulb, this means that the powerline signals have to pass through the filament of the bulb in order to complete the circuit. The reason you can get the wall switch module to turn on but not off is because the X-10 signal has to pass through the lamp, and a hot lamp has a higher resistance than a cold lamp, therefore it takes a slightly higher amplitude of signal to turn a wall switch off than it takes to turn it on. If however you have a big enough signal, you would not notice the difference.
The procedure to solve all these problems:
1. Open the module: unscrew the screw holding the aluminum plate to the triac and carefully push the tabs at the four corners of the case and open the two halves of the plastic case. Push out the RED BLACK and BLUE wires from the plastic notch.
2. Carefully, using a small flat screwdriver push out the PCB from the plastic case. Behind it are the two code wheels and the power cut and switch. The powercut has a small metal tab that you don't want to lose if you want this feature.
3. The area of interest is where the RED wire is soldered in the PCB. It is followed by a 10Kohm 1/2W resistor (brown, black,orange). Replace this with an 8KOhm resistor. Assemble everything back.
You don't have to give up your old regular nice looking switches when installing X10 wall switches. Your old switches may be antique, or better looking or have a better feel to them than X10's push button. You can add any switch which is (or you can turn into) a spring return, to X10.
Thus the original switch controls the X10 module, not the light directly as before. 4. Inserted the module behind the original light switch. The downside of this mod is that its not as straightforward to get to the X10 module, but so far (a few years), there was no need to.
Credit: Steve Bloom
based on these projects:
Excerpts from Dr. Ed Cheung project :
The purpose of this project is to see if its possible to replace the microchip inside an X-10 WS-467 wall switch with a custom programmed microprocessor. The reason is that the stock wall switch exhibits some undesirable behavior. One example is that the switch turns the lamp on full bright when you send it a DIM command when the wall switch is off. The more desirable trait would be to brighten up from off gradually.
Inspection of several wall switches showed that the chip bore markings from the Microchip corporation, fueling the suspicion that it is possible to replace it with a PIC micro (from Microchip). A unit with an A/D converter is needed since the X-10 carrier is fed unamplified to the stock chip, and can have amplitudes in the tens of millivolts.
Results of the investigation
After removing the stock chip, and soldering in a socket, I was able to plug in a ribbon cable leading to a solderless breadboard. This allowed me room to work and experiment.
My initial attempts were successful, I was able to port my X-10 receiver from my home automation library and was able to receive X-10 commands. These commands were succesfully used to control the attached light bulb. The only modifications needed to the circuit board were the replacement of a zener diode and of course the microchip.
I then attempted to send X-10 commands from the wall switch, but the low operating voltage of the PIC and the inadequate signal coupling transformer made this not possible. Specifically, I directly connected both sides of the signal transformer's secondary to the PIC, and drove them in a complementary 'bridged' fashion. This applied 10 Volts peak-peak to the secondary. Due to the 10::1 ratio, this voltage appears as 1 Volt peak-peak on the primary and the power line. As a comparison, a mini controller plugged into the same outlet as the wall switch, produced 5 Volts peak-peak at the signal transformer's primary. Thus we need about a five fold increase in transmit amplitude.
Another issue is the fact that the PIC can sample no faster than 50kHz, while the X-10 carrier is at 120kHz. Since we will thus be subsampling, the apparent frequency of the X-10 carrier in the sampled data will be aliased down to the frequency Tr:
Tr = Tx - nTs, where n is an integer such that: 0 < Tr <= Ts
Thus if Tx is an exact multiple of Ts, the apparent frequency will be zero, and the carrier will not be detected. Since the sampling rate is 12.6khz, the carrier needs to shift by +/- 6.3kHz to cause this.
Finally, since the PIC is not frequency selective, burst of noise by nearby TRIACs can cause the carrier to be distorted compeletely. A better detection algorithm can address this, or analog hardware needs to be added to provide frequency selectivity.
Long Term Update
Leviton released in the Spring of 1997 wall switches that no longer go on full blast when the module is OFF. They are the same price as the regular Leviton switches ($35-$50). Because of this, the value of an Improved Wall Switch has been diminished. This project is on permanent hold at this point, and I am making the source code available for non commercial use.
Thanks to Steven Bloom for his feedback on this mod.
For low voltage operation, the triac in the module must be protected from the inductance of the load, which is induced by the coil of the low voltage transformer.
The following addition of a 'snubber' network is the only difference I am aware of between a wall switch and a 'low-voltage' module, sold for more then twice as much.
The snubber network adds a capacitance and resistance so that the triac sees more of a purely resistive load then otherwise. For more on this, look up 'snubber circuit' in altavista.
Reassembling the power-cut switch
If you choose to use the powercut switch here are two methods to do it. The second one was found to be preferable.
Method 1: Use some electrical (or other) tape to hold the code wheels in place then lift the board into the housing with the little metal power-cut plate balanced on its perch.
Method 2: Take the plastic power-cut slide-switch out of the housing (squeeze the two retaining tabs from the inside with pliers and push them out one side at a time). This way you can reassemble the unit without the metal tab, and after everything is back together, simply drop the tab into place. It's easy to seat it properly this way then push the slide-switch back into its hole.
Modification to a
silent appliance module
The topics range from quieter appliance modules
to ceiling fan control with wall switch to cheaper fluorscent wall switches.
another description of the procedure, including adding a neutral wire
1. Using the schematic as reference and tracing the
circuit out, remove the coil/choke, triac assemble, the 1k resistor, 2 diodes and the
39ohm resistor, noting (with pencil?) the hole positions of each.
Tom Myers wrote in response
This modification requires testing and tweaking the module while it is connected to the mains powerline. This information is provided AS-IS, for informational purposes only, with no warranty whatsoever. It is your responsibility to know and understand common safety procedures, especially those involving electricity at potentially dangerous power levels. Proceed at your own risk.