X10 TM751 Endless Dim Problem

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Well, thanks Dave for the response. Now this is interesting... I noticed that the TM751 was slightly warm when I would go over to unplug it to reset my lamps. I didn't think much of it, but the next time I plugged it in, I put it right next to a fan running in my apartment, with air blowing right across the model. It's been plugged in for at least a couple of hours (a record), and I haven't had an endless dim since (I've been testing it every 5 minutes or so)...

Is there any possibility that an overheating module would cause an endless dim, or is this more likely a coincidence? (even if it's not, I don't really want to run a fan 24/7 just to keep the dimmer working).

And if it does turn out to be a coincidence, is there a newer transceiver module that doesn't suffer from this annoying problem?

Sorry for so many questions and thanks again, Gavin

Dave Houst> It sounds like you've already tried the things that worked for some people.

It may not be entirely coincidental (I suspected the 20 minute abeyance after (de)tuning might be heat related.) but I suspect the heat is somewhat normal (or an effect of the endless transmissions). The TM751 draws 1.2W when idle so should be slightly warm. If you have a ~3W nightlight, the nightlight should be warmer than the TM751.

It's been a few years since I investigated this but I found I could induce it in 100% of the TM751 modules I tested (about a dozen) by aligning the antenna with an extension cord. Inductive feedback of the 120kHz on the line appears to trigger the phenomenon.

The RR501, while not immune, is far less susceptible.

However, I recommend go>Well, thanks Dave for the response. Now this is interesting... I

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Well, I'm pretty sure at this point that it's mostly heat related. With the fan on, it continues to work fine, but after a few minutes with the fan off, endless dims start back up. When I turn the fan back on, the endless dims go away after a couple of minutes.

Too bad there isn't a good spot inside the module for a small copper heatsink. Thanks again Dave, for all your help.

- Gavin

Dave Houst> It may not be entirely coincidental (I suspected the 20 minute abeyance

That's certainly interesting. A fan blowing air over the oputside of the plastic case can't be doing much cooling to the internal electronics. That it makes a difference is surprising. Maybe it's just blowing away bad karma. ;)

I'd love to have an oscillosc>Well, I'm pretty sure at this point that it's mostly heat related.

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If you feel comfortable running it while it's out of the case, you could heat it with a hair drier until it fails then spot cool individual components with some kind of freeze spray until you locate the faulty component.

Dave,

You mentioned the Leviton HCPRF All Housecode Transceiver. I am looking for a transceiver that can receive and transmit all the 256 codes, regardless of which house/unit code it's internal relay is set to. Even this one seems to only be able to respond to the house code it is set to. Isn't there one that can respond to all of them?

Dennis

Dave Houst> It may not be entirely coincidental (I suspected the 20 minute abeyance

The HCPRF receives RF from all 16 housecodes and all 16 unitcodes and transmits PLC to all 16 housecodes and all 16 unitcodes. I haven't checked how many of the function codes it handles but know it handles all the standard ones (On, Off, Bright, Dim) listed in the CM17A protocol doc...

plus All Lights On & All Lights Off. Some transceivers also handle All Units Off and some of the functions can be triggered by more than one RF code.

The Smarthome online specs in the link I gave seem to have been written by someone who has never used one. Look at the User manual (from Leviton) which says, "Cat. No. HCPRF functions as a remote control receiver which accepts ON/OFF, DIM, BRIGHT, and ALL LIGHTS ON/OFF commands of up to 256 DHC codes from DHC remote controls."

That actually makes for 576 codes, 256x2 (On, Off) + 16x4 (Dim, Bright, All Lights On, All Lights Off).

NOTE: There are some limitati>

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| You mentioned the Leviton HCPRF All Housecode Transceiver. I am | looking for a transceiver that can receive and transmit all the 256 | codes, regardless of which house/unit code it's internal relay is set | to. Even this one seems to only be able to respond to the house code it | is set to. Isn't there one that can respond to all of them?

If you are able to do some soldering you might want to look at my replacement PIC code for the RR501 (and TM751, though with less functionality). It eliminates the endless dim problem and allows you to enable any combination of house codes. It is available on my home automation page linked from

Dan Lanciani ddl@danlan.*com

Yes, Dan's replacement PIC works a treat with both the RR501 and the TM751, at the cost being able to use the internal relay of the module. Life's become so much simpler after implememnting the all-house-code.

Thanks, Dan

Anand Dhuru