used x10 since the early 80s including building custom computer interfaces and software ... in the past month I have had 2 TM751s fail ... one is completely dead the other is randomly stuttering (any time it gets a dim command it gets stuck sending dim continuously and wiping out the entire X10 spectrum) ... took them both apart but couldn't find either a fuse (most modules have a whisker open air fuse) OR any noticeable failed components ... went online looking for a schematic ... apparently there was a tm751.gif file on one of the forums but the link is long dead ... several years back I had purchased a CM15A but have never used it ... as it has 2 antennas (one internal and one external), I was expecting it should just act like a TM751 even if it wasn't connected to a PC? The manual for this device isn't very clear on its capabilities ... mostly talks about how to use the PC software ... does anyone recall if the CM15A could work in this capacity (standalone like the TM751) or does it have to be connected to a PC with software much like the TW523?
It can act as a all address [House Code A-P, Unit Code 1-16} transceiver. The software lets you select which House Codes are transceiver. It can stand alone as a transceiver after being told what House Codes to transceive. I believe the default was Auto that only used the ones for modules installed in the GUI.
Since the original X10 Wireless Technologies went bankrupt. The new owners lost the registration servers in the move. So installing Active Home Pro, that needed registration, was not easy. Tuicemen has written a program that allow you to install AHP and four of the added plugins.
The external antenna is the receive one and its range is not too good. About half of the antenna wire is inside the case. Wrapped around the case. Some of us have extended it all the way out and improved the range. Others removed the antenna and installed a BNC Jack with an external antenna.
I will see if I can find any sites with active schematics. I do know there are more than one hardware version of the TM751 and many other modules.
The TM751 and RR501 schematics and photos are not in the FCC Database. The older CM15A schematics and photos are on the FCC web site. The newer CM15A with the RF receiver and RF transmitter on the main board and surface mounted controller. Are not there.
I did a test. With what I believe is factory settings. Blank Room with No modules. Cleared downloaded memory. Tranceived House Code Auto. No House Codes where tranceived. Set to Tranceived House Codes. Specific and enabled A and P. A and P tranceived. Other 14 not. Set to Tranceived House Codes. Specific and enabled all 16 House Codes. All tranceived. This was not on the computer after each change and no batteries installed.
The CM15A is far superior then the tm751. It has memory and a polite transmitter meaning it waits for the power line to be clear before sending a x10 command. I've never experienced range issues BLH mentioned but I have it mounted on the second floor.
Installed an archived copy of ActiveHome Pro and was able to configure the CM15A to the point where it is now receiving commands from a PowerHouse 8 in 1 remote with 3 noticeable differences: 1) the remote RX range is much less then the TM751 ... will look at antenna mods ... maybe just transfer one of the antennas from a failed TM751 2) there is more of a lag in time between RX and X10 action 3) I suspect the CM15A X10 signals may be weaker then the TM751 as it is having difficulties controlling devices on the 2nd AC phase ... the TM751 has a polarized AC plug where as the CM15A has an internal transformer to isolate circuitry from the mains ... having a transformer means it can be plugged in to the wall in any polarization ... cross phase x10 signal coupling can sometimes be improved by just flipping an X10 transmitters plug
At least for now I have manual remote control restored
1) As a quick thing to try. Tape or fasten an 18" metal rod on to the external part of the antenna. 2) If there is any noise the CM15A thinks is on the power line. It is polite and maybe temporarily holding off sending the power line commands. 3) Depending on how old the TM751's where. It is possible the CM15A has a lower PLC signal. There was a change in the TM751 and old ones had a higher PLC signal.