A friend has an old Radio Shack remote outlet control. It oddly will turn a lamp ON remotely, but will not turn it off. Any ideas?
The 9V, handheld transmitter has separate buttons for "on" and "off". A small LED lights when either is pressed. Once the receiver's remote outlet latches on, repeated presses of the transmitter "on" button make no difference. And as I said, pressing the "off" button does nothing either.
You can see in the photos that a Motorola encoder/decoder pair is used to send the message; MC145026 encoder and MC145027 decoder. A "valid transmission" output is produced when the right code is received and a nibble of data can also be passed. I don't see any other ICs smart enough to use a data nibble, so one thing I don't understand is how this thing differentiates between an "on" signal and an "off" signal.
The receiver switches the outlet with a relay rated to 30A at 220V. It uses a transformer-less power supply - a capacitor (the big blue one) and diode followed by an electrolytic capacitor. There's also a zener diode nearby and I think that "regulates" the voltage for the rest of the circuit. There is evidence of heat aging in the vicinity of that zener, which is right next to the big electrolytic cap, both on the right hand side of the 2nd photo.
I'm thinking of replacing that big electrolytic cap for good measure, but otherwise I don't have a clue how to proceed. I have no way to tell if the problem is at the transmitter or the receiver.
The 9V, handheld transmitter has separate buttons for "on" and "off". A small LED lights when either is pressed. Once the receiver's remote outlet latches on, repeated presses of the transmitter "on" button make no difference. And as I said, pressing the "off" button does nothing either.
You can see in the photos that a Motorola encoder/decoder pair is used to send the message; MC145026 encoder and MC145027 decoder. A "valid transmission" output is produced when the right code is received and a nibble of data can also be passed. I don't see any other ICs smart enough to use a data nibble, so one thing I don't understand is how this thing differentiates between an "on" signal and an "off" signal.
The receiver switches the outlet with a relay rated to 30A at 220V. It uses a transformer-less power supply - a capacitor (the big blue one) and diode followed by an electrolytic capacitor. There's also a zener diode nearby and I think that "regulates" the voltage for the rest of the circuit. There is evidence of heat aging in the vicinity of that zener, which is right next to the big electrolytic cap, both on the right hand side of the 2nd photo.
I'm thinking of replacing that big electrolytic cap for good measure, but otherwise I don't have a clue how to proceed. I have no way to tell if the problem is at the transmitter or the receiver.
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