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[GeorgeM]

My CM15A is about 2 years old, and I have experienced slow loss of coverage to the modules.  My old X-10 manual controllers still work just fine, so I suspect the CM15 has either drifted off frequency or lost output, rather than there being a noise or suckout problem.  I downloaded the schematic and checked the inside for obvious problems, but see no burnt parts or bulging electrolytics.  Voltages are as apecified.  I tried the link in the Forums to the level meter, but it is no longer valid, I would appreciate a lead to that item.  And, any suggestion on turning on the X-10 signal continuously in order to accurately measure it.  Comparing it on a spectrum analyzer with an X-10 Command Console, it appears to be 5 - 10 kHz low.  Any guidance appreciated.  

[Dan Lawrence]

My CM15A is 4 Years old, bought in 2005 and is still going as strong as the day it was set up. All my modules work as they always have. Could possibly yours is getting interfered with, like the PC it is connected to that has AHP installed on it, and no noise filter or the noise filter you have needs replacement.

[GeorgeM]

No, and No.  I only connect the computer to correct the time every couple of weeks.  I carefully monitor the electrical configuration to correlate changes with performance.  When the unit was new, I could place it almost anywhere and it would control all the modules.  I have had to find better locations twice since then, with essentially no changes in electrical loads.  Interestingly, it reliably controls an outside light some 200 circuit feet away, but no longer the lamp in the guest bedroom.  That change happened last week, and no other electrical changes were made last week.  I have become very sensitive to bulb changes, and what is plugged in where since this problem started escalating.

[Brian H]

Not sure what tester you where linking to.

I know both the ELK ESM1 and Smarthome TesterLinc are both discontinued for a long time now.

http://jvde.us/
http://jvde.us/xtb/XTBM_description.htm
http://jvde.us/x10_troubleshooting.htm

Anything new for the holidays? Even a new cell phone game console or electronic gadget could be changing things.
Whet type of new bulbs? CFLs can be a problem in some installations. Also an aging CFL near end of life could be generating more noise.

There was a post here a very long time ago, where somebody re-tuned the coils on the board. I believe in their case it was for the receiving portion, but maybe the transmitter also.

[dave w]

My CM15A is about 2 years old, and I have experienced slow loss of coverage to the modules.  My old X-10 manual controllers still work just fine, so I suspect the CM15 has either drifted off frequency or lost output, rather than there being a noise or suckout problem.  .  

George, FWIW
Your troubleshooting assumption seems sound, however when compared to the X10 wired controllers and the two X10 tranceivers, the CM15A has a decidedly lower output. So you could still be seeing a growing noise problem, such as a dying CFL. With the lower output, you would see it first in the CM15A.

I have the Volp XTBM meter and two ELKs. The XTBM is the "Fluke" or "Hewlett Packard" of X10 signal meters.

[Brian H]

dave w; The CM15A must have been changed by X10.
I saw tests of the early ones and most times the CM15A had a higher signal output than most wall powered transmitters.
Side note. I sent an order for an XTBM kit yesterday.

[GeorgeM]

Well, forum, thanks.  It turns out that it was off frequency.  And, 120 kHz is NOT the frequency.  I ran a check using my old X-10 transmitters, and the sweet spot in my system, where the fartherest modules respond most reliably, seems to be just below 130 kHz.  This is the best response for a bunch of old receivers of all kinds and ages, which don't seem to like 120 kHz near as well as 130.  All my notes indicate 120 kHz is the design frequency, but my modules seem to disagree.  So, I set the CM15A to 129.3 kHz, peaked the output, which is within a dB or two of the old X-10 controller outputs (you are right, Brian H), and things are back to working good.  Unfortunately, I had already moved the slugs in the transformers before I set up to accurately measure the frequency, so I do not know exactly where it had drifted to.

I looked at the noise around 120 kHz on my AC service, and found a litttle.  In tracing the source(s), it turned out to be coming from the various X-10 receivers.  With them disconnected, all was quiet.  When I turned on my CFLs, they were mostly around 50 kHz, and harmonics thereof.  So, any switching at 60 or 65 kHz would sure wipe out an X-10 system.  One reason I keep things quiet around 100 kHz is I am using a Loran C receiver to discipline a frequency standard I maintain.

Test note:

I measured the frequency with a HP 8558B spectrum analyzer referenced to a signal generator and counter.  I measured the relative outputs using a Tek P6021 current probe, with a B&K 1655 as the AC interface for consistent load impedance for the DUT.

For forum future reference.  TC3 controls the transmit frequency, TC1 peaks the output, and TC4 is the receiver input.  The FCC place with a list of the schematics, etc. for the CM15A is: <https://fjallfoss.fcc.gov/oetcf/eas/reports/ViewExhibitReport.cfm?mode=Exhibits&RequestTimeout=500&calledFromFrame=N&application_id=476706&fcc_id='B4SCM15A'>
The schematic and other drawings are in .pdf.

Again, thanks for the inputs, and making me think harder.

[Brian H]

I have also seen steps to retune the modules on a few forums.
I also don't think X10s Chinese Assemblers went out of their way to do a precise tuning or use precision parts. Not when the mega module sale is selling eight for $49.00.

Thanks for posting the FCC site. I had posted it maybe a year ago and it is good to see it again mentioned.

Helpful post from me.

[JeffVolp]

120KHz IS the design center frequency, as specified in the X10 Communications Protocol document.

Measuring a number of devices around here, I found that an old boxy Sears controller transmits at about 130KHz, but my RR501, TM751, and the newer Maxi Controllers all transmit between 118KHz and 122KHz.  The XTB-IIR transmits very close to 120KHz because it is frequency locked to the powerline.

Since ceramic capacitors decrease in value slightly as they age, that could explain why that 30 year old Sears controller is off frequency.  How much they shift depends on the material:

        COG:  no change
        X7R:  -2% per decade of time (in hours)
        Z5U:  -5% per decade of time (in hours)

Because the capacitance changes rapidly in the beginning, it is usually measured after at least 10 hours.  Kemet says the test limits are set so the capacitor should meet the manufacturer's tolerance after 1000 hours.  Their chart shows the value of a X7R capacitor will decrease 2% over the next 10,000 hours, and then another 2% as it ages for 100,000 hours.  Obviously, a Z5U would drift much more, but I doubt anyone would use that for a frequency determining circuit.

This information was extracted from the Kemet Gold Max capacitor catalog.

Depending on what type of capacitors were used in those old X10 modules, and how "fresh" they were when the device was tuned, it is possible their center frequency could have shifted higher as they age.

Jeff

[Brian H]

The old X10 patent also says 120KHz.
Sounds like yours have drifted or where not that close to begin with.

[dave w]

dave w; The CM15A must have been changed by X10.
I saw tests of the early ones and most times the CM15A had a higher signal output than most wall powered transmitters.
Side note. I sent an order for an XTBM kit yesterday.

Thanks Brian,
Somewhere along this road I thought I remembered reading the CM15A is only about 0.7V where as the and the Maxi controller was about 1.2V, with TM751 falling between. Guess I need to do some testing with the XTBM.

I think GeorgeM is on to something regarding tuning your modules. I need to find a cheap O'scope on eBay, so will have something to do around the house after becoming un-employed this April. Will be fun 

[Knightrider]

FWIW:

Here's some frequency results from the Knightmare using a XTBM:


Sears controller: 121k
CM15A :117k
KeyPadLinc :118k
Wife's CM15A:  118k

My "junk" CM15A which does not work with PLC anymore is running 130k and the modules do not respond.

This is my original CM15 purchased in 2004 or so and I've been using it for RF only through BXMC (Bill's X10 Manual Control).  Looks like I've now figured out how to repair it.

Thanks guys!!!

[GeorgeM]

One final comment.  It is always possible that all my receivers were slowly drifting upward, while the CM15 was not. 

Knightrider:  Tune TC3 CW a quarter turn at a time while watching your most unreliable module.  Disable the relay(s) of course.  Note where it starts to respond.  Keep turning until it quits again.  Then turn the slug back CCW half way between, and you should be good to go, without having to buy that 'scope.
Good luck.

[Knightrider]

GeorgeM,

Would you believe that in all this time I never worked up the gumption to just open that bad boy up?

THANK YOU for the sage advice!!!!!

Looks like I'll have something to do with myself this week-end.

+1 from me!!!!

 

[GeorgeM]

Knightider:

The four screws in the CM15 case seem to be Posidriv® #1, and require a small diameter driver.  A small #1 Phillips will work if you keep a lot of pressure on it.  Otherwise, no particular surprises inside.  And, if you have a reliable way to measure frequency, which apparently you do, just adjust the slug as needed.  The output coil may or may not need peaking, hard to predict.  TC3 is on the notched end of the board with the TR6 legend adjacent.  See the photos at the FCC address I listed for a preview of what you will see inside.  Photo #2 is the component side of the main board.  The can nestled among all the components on the other side of the board is the output tuning.