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[kenwood850]

Recently with the seasonal installation of some X10 modules for Christmas lights I found some modules were not responding to commands as they should. In the past however, if my memory is not faulty, they responded in all locations without a problem.   

At the main electrical panel I have an XPCR unit that has been installed for several years and also installed are two 250V 1Mfd capacitors in series across the two phases.   I also have an old carrier current intercom kicking around that I found can be used to hear the X10 signals if I open the squelch all the way.

What I have discovered on investigation is that with the two breakers closed so that capacitors are connected between the phases, I can here X10 signals on the intercom when the source is on one phase and the intercom is on the other.  If I open the breakers on the capacitors, I cannot hear any X10 signals in the same configuration.  If I then close the breakers connecting the XPCR, I still cannot hear the X10 signals on the intercom even though the light blinks twice on the XPCR with each command given.

 From what I have seen, actually heard, I am pretty sure the XPCR has failed but I have several questions.


1. How many times should the light blink on a properly operating XPCR?   I have a feeling the lights are only showing the reception of the original double burst signal from the source and it is not repeating it.   The only thing I can find in the instructions is that the light blinks but there is no description of how it blinks. 

2. If it has failed, and it appears that it has, I am also guessing that since the light still blinks on signal reception, fixiing it is probably not as easy as replacing a MOV or some such and it is best just tossed but I am open to suggestions.

3. As an aside, and nothing to do with my problem, in searching through past posts on XPCRs to see if I could find a blink sequence, I found where someone said that the both breakers connecting the XPCR should be closed simultaneously with no real explanation as to why.  In the past I have flipped one breaker on and the other since they are not ganged and not had a problem.  I am curious as to the rational for that statement.   I would think as long as the neutral remains connected it would not be a problem.  Even a ganged breaker might have some time difference even if it is very small.

[Brian H]

One clarification.
You have both a XPCR and a passive capacitor between the same two incoming power lines?
So you are coupling the XPCR outputs back into each other.

1) I put my test XPCR on a test rig. After fixing it.
The LED flashed two times.
2) Hard to say. Probably not a MOV as I will elaborate shortly.
If the passive coupling capacitors worked but the XPCR with out the capacitors connected didn't. It could be a defective XPCR.
3) Some Coupler Repeaters have issues with power on one line only. I don't think this is a problem with an XPCR as in most installations the second Black wire is not connected to anything. Power is taken from Red to Neutral. If it is Off the unit is not powered.
Turning on one at a time maybe OK. With my XTB-IIR. connected to separate breakers. I try and flip both on at the same time.

Side note. NEVER power up an XPCR if the Neutral is missing. The MOVs and fuses for the Red and used Black Line wires will. Blow out and emit magic smoke. I replaced both fuses and MOVs and tested it. Seems to be fine with the tests I ran.
Tried both Black wires along with the Red. All seemed to have about a 3 volt X10 output. On a XTBM X10 meter.

If the modules where in storage. You may want to rotate the House and Unit Code dials a few times. Some times they get dirty and the code set is not what it thinks it is set too.

[JeffVolp]

With my XTB-IIR. connected to separate breakers. I try and flip both on at the same time.

There is no reason to do so.  It is powered off Phase I.  Phase II is strictly a 120KHz tuned-circuit coupling network.

Side note. NEVER power up an XPCR if the Neutral is missing. The MOVs and fuses for the Red and used Black Line wires will. Blow out and emit magic smoke.

The MOVs and fuses were popped in a couple original XTB-II's that were misswired.  The surge protectors and coupling networks in the XTB-IIR will withstand 240V so no damage is done if the neutral is open.  (It just won't work.)  If 240V is connected across Phase I and Neutral, the user replaceable fuse will pop.

Jeff

[Brian H]

Thank you for the information Jeff.

My thoughts are. There is a MOV from each Line to Neutral.
With the Neutral open there was 220 volts across two of them in series. Since they are not precision components. More voltage was on one of them and it started to fail. Then most of the voltage was on the second one and it also failed.
Thank goodness the real small gauge wire blew open from the close to shorted connections of 220 volts.

[kenwood850]

One clarification.
You have both a XPCR and a passive capacitor between the same two incoming power lines?
So you are coupling the XPCR outputs back into each other.

I am not sure why that would make a difference unless there was a difference in amplitude or phase in the X10 signals between each leg.  If there was a difference in amplitude I could see that stronger signal using the capacitors to reinforce the weaker leg, but I am not sure that would not be a good thing.  As far as a possible difference in phase, I would think that both legs would use a the same generated signal to avoid that issue or otherwise there could be destructive interference or distorted signals with or without the capacitors. I will however try it both ways and see if there is a difference and that I am laboring under a misconception.

1) I put my test XPCR on a test rig. After fixing it.
The LED flashed two times.

Interesting.   I was not expecting that.  Do you know if the XPCR waits until the incoming signal is completed before repeating it.   That is what I would expect to avoid a collision that might result in the signal being distorted and unusable.  Perhaps the blinking light shows only the incoming signals.

2) Hard to say. Probably not a MOV as I will elaborate shortly.
If the passive coupling capacitors worked but the XPCR with out the capacitors connected didn't. It could be a defective XPCR.

The day after my initial post, my thoughts finally had enough conviction as to it being a bad XPCR as well so I ordered a replacement unit.

After placing the order, I removed the current unit from the panel and opened it up to see if that magic smoke your mention had escaped and there was nothing obvious.  On the power supply board there was some discoloration on one side of the board where the largest SMD capacitor on the opposite side of the board is located.   It looked like the discoloration of long term heat rather than the result of a catastrophic failure.   

3) Some Coupler Repeaters have issues with power on one line only. I don't think this is a problem with an XPCR as in most installations the second Black wire is not connected to anything. Power is taken from Red to Neutral. If it is Off the unit is not powered. Turning on one at a time maybe OK. With my XTB-IIR. connected to separate breakers. I try and flip both on at the same time.

Side note. NEVER power up an XPCR if the Neutral is missing. The MOVs and fuses for the Red and used Black Line wires will. Blow out and emit magic smoke. I replaced both fuses and MOVs and tested it. Seems to be fine with the tests I ran.
Tried both Black wires along with the Red. All seemed to have about a 3 volt X10 output. On a XTBM X10 meter.

All good to know. Thank you.

If the modules where in storage. You may want to rotate the House and Unit Code dials a few times. Some times they get dirty and the code set is not what it thinks it is set too.

Another good thought.  In this case I confirmed the module was working from another outlet and even tried several different modules by different manufacturers in case the signal was borderline and one module might be more sensitive than another.  No luck.   

Thanks for taking the time to reply.

[Brian H]

I don't know how the XPCR receives and then repeats the messages.
I suspect. It receives a message on a phase. Then sends it after it is complete.
Maybe timed to the phases Zero Crossing signal. As it has three outputs and can be used on a three phase 208 Volt or split phase 220 volt system.

I have seen some reference to some controllers sending three messages timed so one of the three matches each phase in a 3 phase system.

I thought I saw information on not having both an active repeater and passive coupling between the phases. Don't off hand remember why.

[roger1818]

Having both an XPCR and capacitors across the phases will definitely cause problems.  One of the issues with using the capacitor solution is that 240V modules won't work since the signals on the two hot wires are in phase, so the delta between them is zero.  The XPCR solves this by transmitting inverted signals (shifted 180 degrees) on opposite phases, so that the delta between phases is 2X.  If you have both installed, it will short out the transmissions from the XPCR and could potentially damage the transmitter.

[dave w]

One of the issues with using the capacitor solution is that 240V modules won't work since the signals on the two hot wires are in phase, so the delta between them is zero. 

I don't think I understand that. Signals would be 180 degrees out of phase, wouldn't they?

[kenwood850]

The new XPCR arrived today and I installed it this evening.   Everything is turning off and on as it should so it would appear the old unit was indeed defective.   If the new unit lasts as long as the old one, I will be happy.

I was a little confused as well but after thinking about it, Roger1818’s explanation makes sense for the same reason the two 120V legs have to be 180 degrees out of phase to achieve 240V.  I would guess if there is a 5V X10 signal between one leg and the neutral there would be a 10V signal between the two legs by having them out of phase by 180 degrees.  Placing the same X10 signal on both legs would still achieve 5V of signal between each leg and the neutral but 0 V between the two legs when there is no neutral.  If you put the capacitors between both legs for coupling you are essentially shorting out the 10V signal since the impedance is probably less than 5 ohms.   In my installation, it probably does not make much difference if the signal between each leg is in or out of phase since all my modules are between one leg and neutral, but since there are 240 V modules, I can see why the XPCR is designed the way it is and why the capacitors should not be used.

In my case the capacitors, as is the XPCR, are on their own dedicated breakers so I have turned the breakers off but left capacitors in place in case of another XPCR failure down the road.


Thanks to everyone for their explanations and suggestions.

[Brian H]

You may want to look at Jeff's great set of X10 troubleshooting tutorials.
The one on Passive Couplers and Repeaters maybe particularly interesting.
http://jvde.us/x10_troubleshooting.htm

[roger1818]

One of the issues with using the capacitor solution is that 240V modules won't work since the signals on the two hot wires are in phase, so the delta between them is zero. 

I don't think I understand that. Signals would be 180 degrees out of phase, wouldn't they?

The 60Hz power would be 180 degrees out of phase from the transformer on the pole (the capacitor acts as an open to it), but to the 120KHz X10 carrier, the capacitor acts as a short, so the X10 signals will be in phase on both power phases (with a slight signal reduction).

[JeffVolp]

I would guess if there is a 5V X10 signal between one leg and the neutral there would be a 10V signal between the two legs by having them out of phase by 180 degrees.  Placing the same X10 signal on both legs would still achieve 5V of signal between each leg and the neutral but 0 V between the two legs when there is no neutral.

That is correct.  And the original version of the X10 XPCP passive coupler did invert the phase of the 120KHz when connected per the instructions.

It is interesting that the newer version in the "Decora" plastic case does not invert the phase when connected per the instructions, so both phases have the same signal.  That is the approach I took with the XTB-IIR because any 240V resistive loads like a stove or water heater would also severely attenuate flipped phase signals.

There are very few 240V X10 loads out there, and when one exists, the fix is to attenuate the signal on one 120V leg at the 240V load with a capacitor to neutral.

Jeff

[Jeff Weems]

I am replying just for the record.
I bought an XPCR from Amazon.com 1/26/2019.
The box and the device appeared to be brand new/unused.

I carefully installed per the instructions provided with the XPCR.
I used an XTBM to verify that XPCR responded, X10 signals were repeated across the 120V phases, and X10 signals amplified by about 5V near the XPCR. The LED on the XPCR was flashing as signals were repeated.

After maybe an hour there were X10 misses, and the XTBM showed no repeater on the system. The LED on the XPCR was not flashing.
I power cycled the XPCR and then it worked correctly again, but only for an hour or so, and then once again the XTBM reported no repeater, there was no repeating, and the XPCR LED was not flashing.

I have ordered an XTB-IIR and have other options I will pursue. The XPCR description sounds good, and the price is low, but based on my experience not a reliable device. If anyone is successfully using the XPCR and has any suggestions for me I'd be interested.

[brobin]

You made the right choice ordering the XTB-IIR as it is far superior to any other repeater/coupler/amplifier ever made - and I believe I've tried them all. It just works.