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🛡Home Security => Problems and Troubleshooting => Topic started by: GPL on June 10, 2020, 12:37:57 PM

Title: XM19A power adapter, help needed to troubleshoot
Post by: GPL on June 10, 2020, 12:37:57 PM
Hi,

My SC1200 unit  has stopped controlling the lamp modules and the power horn.
I checked with an oscilloscope and found that the SC1200 is sending the X10 controlling signals as well as receiving a square wave synced to the power line from the power supply.

I assume that something is wrong to the XM19A power adapter and it cannot insert the right 120KHz bursts on the power line.
If someone has the schematic diagram of the XM19A unit and  information how to tune the two coils mounted on its board please make a post.

Thank you
Title: Re: XM19A power adapter, help needed to troubleshoot
Post by: Brian H on June 10, 2020, 12:56:02 PM
As you found.

The XM19A has the power line transmitter in it.
The signals are common ground, DC+, keying pulse from the SC1200 to key the X10 transmission on and off and the Zero Crossing pulses for the SC1200 to time the transmitter keying pulse.

You may want to look at the DC+ and Common to see if it is excessively noisy or the Zero Crossing signal is messed up. My usual suspects would be electrolytic capacitors drying out.

Another possibility would be the power line transmitter circuit. Getting the proper keying signal but not putting a signal on the power line.

I have not seen any schematics or service tips for it. Maybe a similar function supply may have information on it you could use as a rough schematic of the XM19A.

I did roughly tune one with my XTBM showing signal strength and trim it closer to the 120KHz.

If worse comes to worse. X10 sells a replacement XM19A. Though they show it out of stock.
Title: Re: XM19A power adapter, help needed to troubleshoot
Post by: GPL on June 25, 2020, 06:28:47 AM
It is strange, although I have found the schematics for almost any X10 module, I didnít find the drawing for that PSU, so I had reversed engineering the schematic from the pcb.
Title: Re: XM19A power adapter, help needed to troubleshoot
Post by: Brian H on June 25, 2020, 07:12:55 AM
I am not too surprised about no schematic. The MT12 and MT13 also have a similar power supply. I doubt they have a schematic available also.

You may also not find the schematics for the presently sold Lamp and Appliance Modules. Completely new designs. New surface mounted Sonix SN8P2501 controller and power supplies around 3 to 4 volts. On my Lamp modules. Not even a regulated supply. Voltage goes slightly down when turned on. My thought gate current for the Triac.