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[bkenobi]

I have one of these old Radio Shack controllers that the previous owner left in my shop.  It's worked fine for me for over 5 years until tonight.  It can now only send commands to the one module in the shop but cannot control modules at the house.  My XTBM indicates 0.19-0.27 signal strengthwhen plugged into the same outlet.  I have a XTB-IIR in the main panel location around 200 feet away but I get no repeat meaning that the signal is too weak for the repeater to properly detect the command.  I get the response from the repeater when I plug in the XTBM at 4.50, so that's not the issue.

Is there anything that can be done to easily and/or affordably repair the signal or should I look for a replacement?  I assume the best direct replacement is the Mini controller MC10A.

[toasterking]

I am not sure, but I think you may be referring to the 61-2677C which appears equivalent to the X10 MC460 Mini Controller.  I had an MC460 stop transmitting entirely.  The procedure on this page (scroll down to "Fixing the Mini Controller") fixed it for me:
https://www.idobartana.com/idobartana/hakb/modifying_mini_controller.htm
FWIW, my unit wasn't working at all at the time I performed the repair, and the LED stayed on solid even though no button was being pressed and nothing was being transmitted.  It may not be the same failure as yours.

[bkenobi]

I pulled the cover off and noticed the black heat damage shown in the link.  My first thought was that these were likely the culprit.  The link you provided confirms that suspicion so I'll try replacing the diodes.  Thanks!

[Brian H]

I would also replace the power supply capacitors. They tend to dry out and not work as well, with age.

I had an RR501 where the PCB was dark brown and the solder has started to get crusty around the Zenner Diode in the power supply.
I replaced it with two in series. Each half the voltage and same wattage as the original. I also changed the main filter capacitor for goo measure.

[bkenobi]

I can do that. Do you have a part number for them?  I can see one is 2.2K 250VCMC But the other 2 are not visible.

[bkenobi]

 I replaced the 2 diodes but saw no improvement. I see 3 large blue components but only 1 appears to be a capacitor to me.  The cap next to the adjustment screw is marked 1000uf 25v. The large component on the other side is labeled 2.2K 250VCMC. The smaller component below that one and next to the other adjustment screw is labeled .22K 250VC(M?).  Which ones should I source?

[Brian H]

The 2.2K is used to limit the current into the power supply. The .22K is most likely the X10 signal coupling to and from the power line.
Both look like a Mylar type. I would say they didn't have to be changed. Dave may have a better handle on them going bad.

Now the 1000uf/25 volt is an electrolytic capacitor and is subject to drying out and deteriorating. That one should be changed. As it is the main filter capacitor for the power supply.

[dhouston]

While X10 may have used a slightly different design, this PDF explains transformerless power supplies with example schematics.
ww1.microchip.com/downloads/en/AppNotes/00954A.pdf

As Brian suggested, the large mylar cap is likely part of the power supply while the electrolytic is the storage cap shown in the capacitive supply example. I don't believe mylar caps fail with age in the way cheap electrolytics do.

One of the diodes was likely a zener - if it blew it would likely take out other components. I'm clueless as to a likely value but the PL513/TW523 schematics might have similar power supplies.
tinymicros.com/mediawiki/images/1/1d/X10_Protocol_Technical_Note.pdf

Could this be a 61-2677B? RadioShack used to have manuals, parts lists, schematics, etc. online but now that they've gone the way of X10, I've no idea whether anything might still be available.

[bkenobi]

I removed the electrolytic cap and tested it.  No capacitance at all.  I checked the polarity and same result. Just to be safe, I tested a good cap and the meter works fine so I'll see if Radio Shack caries basic supplies these days.

[bkenobi]

Radio Shack didn't have exactly the same capacitor, but they had one that should work from what I've read.  The original cap is 1000uF 25v but Radio Shack only has a 1000uF 35v which is rated at a higher voltage so should work I believe.  However, I tested the cap prior to installation and my DMM indicated no capacitance.  I tested a few other electrolytic caps in my supply box and they all reported the correct capacitance.  Is it possible RS sold a dead cap or is there something I'm doing wrong testing?

In any case, I installed the cap and the module still produced 0.14 signal strength.  I don't know if reporting no capacitance means open connection or no connectivity.  I removed the cap and tried sending a signal briefly and found it had zero signal, so clearly the cap does something.

So should I source another cap or look at something else?  Maybe one of the components is a fuse that's blown?  I don't see anything that looks like a fuse to me, but I'm used to the replaceable glass type.

[Brian H]

In your photo.
To the left of the two diodes. It looks like a coil. You may want to check its resistance as some X10 power line supplies had a coil in series with the line.
Also just above the diodes and below the small tuning can. There is a small capacitor. It has gunk on it but it maybe just some glue. If its side is blown out. It may have failed.

Yes a 1000uf 35V is fine. As long as it was not physically too large to fit correctly.

[bkenobi]

The new 1000uF cap is identical size.

I'll check those other two items.  They were the two I was eyeing but didn't know what they were.  I'll see if I can find any markings.  Since they are easy to remove I may just pull them to see if the markings are hidden and/or perhaps locate some hidden damage.

Any thoughts on the new cap not indicating capacitance with my DMM when tested?  Seems like a problem to me.

[bkenobi]

The cap next to the tuner is marked 152J 250. I tested it and the meter reports 1.65nF capacitance.  The beige component (coil) has no markings and no visible damage. It has continuity but I don't know how else to test it.

[Brian H]

152J 250 is a 1.5nF capacitor. A 1.65nF is probably some added offset in the meter. Mine at that low a capacitance has some residual level even when not connected to anything.

The coil is probably OK also.
 
No capacitance reading on the new capacitor is suspicious. Unless your meter can't read 1000uF and is over range. Though most meters will give an out of range indication.

Can you safely measure the DC voltage across the 1000uF/35V capacitor when the unit is powered up?

[bkenobi]

I pulled the cap and am going to exchange it.  If the new one doesn't register capacitance on the meter, I'll check voltage.   I'd be surprised if it couldn't measure 100uF since I've tested caps in the nF to MF range before.