I would like to relate an interesting problem that I discovered. I
recently purchased two refurbished IBM 8514 VGA monitors for both my and
my wife's computers that we have at the house. Shortly after setting up
these monitor I noticed that several x-10 modules both wall switch and
plug in type would not reliably respond to command from either the CP-290
controller or from several of the maxi-controllers in the house. I
presumed that the phase-to-phase coupler needed to be replaced. I built
another coupler and installed it but there was no change in the operation
of the offending modules. I tried substituting the plug-in modules with a
known good spare but again no improvement. I thought back to any changes
in appliances or equipment in the house. The refurbished monitors were
the only change that I could think of. I checked to see that the power
switches to the computers were off as well as the monitors. Still no
improvement. I finally decided to totally unplug the computer systems and
as if by magic all of the x-10 modules and controllers including the rf
remotes were working perfectly. Simply plugging the computers back in the
ac outlet let to immediate module problems. I started to isolate the
computer equipment piece by piece and decided that with either of the IBM
8514 monitors plugged in I started getting module problems. Althought the
power switches on these monitors was turned off there must still be some
sort of circuitry active inside the monitors that emit enough noise to
cause interference with the 120Khz x-10 signals. I tried a couple of
power line filter and settled on the Radio Shack Twin Outlet Power
Protector #26-1395A. I found these at the local store on a close out
table. One of these was used for each computer system in front of the
monitor and cpu. The printer also has a filter for good measure. This
particular filter comprises three fused movs with indicator light for
normal mode and common mode spike protection and a balanced pi-type
filter as well as circuit breaker. Normally you think of a power line
filter to keep trash out of a piece of equipment but it can also be used
to keep trash out of the power line. This has been a bit long but I
thought this might help someone else who might be having similar
problems.
Allen.....
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| Allen Kass, Chief Engineer WRVQ Radio Q94 Richmond, VA. |
| Voice: 804-756-6481 Fax: 804-755-6077 |
| Home page: http://www.infi.net/~allenk/index.html |
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