Modyifying the X-10 RR501 Transceiver


I have successfully completed this modification three times, however, and I accept no responsibility for the effects of anyone making these modifications.   You follow these instructions at your own risk.

Modification Steps

(I've been advised by Mike Greenleaf that the C25 and C26 annotations may be reversed, so please check this; I'll update in due course). 

  1. There are at least two different version of this module. Open it up by removing the screws and remove the PCB.
  2. Change capacitor C26, usually blue, (2E225) from 2.2uF 250V to 1uf 400V. Fix this one with silicon or epoxy glue.  This is the large capacitor.
  3. Change capacitor C10, also usually blue, (2E224) located close to the output connector, from 0.22uF 250V to 0.1uF 400V. It could be called anything else than C10 in other versions.  This is the smaller capacitor.
  4. Check that the 330k resistor, close to C26, the big capacitor, is 0.5W. It should be physically bigger than all other standard resistors. If not change it to 330k 0.5W.
  5. Change the 220K 0.5W (in some models 0.25W) close to the output connector to 470k 0.5W.
  6. Change the 130V MOV in parallel with the05-May-2011 9:58 PM05-May-2011 9:58 PM>y">If there is a resistor of 330k 0.25W going to the output connector, change this one to 470k 0.5W.
  7. The built in appliance module is using a cam relay with a 110V coil and is quite useless and noisy. I did not try to modify this part so I just disabled it. Just cut one of the white wires going to the coil of the cam relay. Cut both ends so nothing can move around and cause a short circuit.
  8. I prefer to de-solder the incoming power connectors and replace them with a cable with my own connector. Use a big, 100W, soldering iron and remove the blades by heating them up and push them through the plastic case.
  9. Also cut away the plastic support for those blade in the box giving you more room for your new cable. A good place to make a hole is in the big square hole on the bottom side close to the outgoing connector. Drill inside the big square hole another round hole towards the centre and pass your cable through. Solder the cable to the big pads where the original incoming connector was.

If you attempt these modifications, please let me know your results, and read the warning on the X-10 and 115V & 230V  page.

Reports received at Redoak

In April 2011, I had a report from Phil Simpson in the UK that the modified units do not last long as two diodes near the large blue capacitors are burning out and failing. I do not know the reason for this, but I am guessing the large capacitor is passing two much current and may need to be reduced further. As I do not have the circuit diagram for this unit, this is just a guess. Please be cautious.

I have had a report from Mun Wai from Malaysia that there are two MOVs in this module, so both must be replaced with 275V MOVs.

In Feb 2010, I had a report from muzzag50 in Australia that the modification worked (with the appliance module disabled) but with difference resistor and capacitor references.

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