From the position and orientation, I think those components could be 240v diodes, making a crude half-wave rectifier. They might also include resistors to drop voltage. One of the traces on the back should be leading directly to that large black capacitor. Check the voltage rating written on that capacitor - if it is less than 240v, and the circuit has not passed through a separate resistor, then those components are what I suggest - combined diode and resistor.

Check across those little components with your multimeter to see if resistance is significantly different one way to the other way. If they are diodes, you should get very high resistance in one direction. The one that is oriented to allow current to flow into the circuit is the one that should have the active AC line attached.

If that is the case, then the only real significance to the polarity would be if one of the poles is switched and the other is not. If there is a single-pole switch in the AC, then make sure that the active line is the switched one. However, clock-radios usually do not have a power switch, as for obvious reasons they are designed to remain switched on constantly - not much point in switching on your electric clock only when you wake up!

Also study the circuit to identify if there is a common ground plane - the markings on the electrolytic capacitors will indicate which is ground. Then check which of the power inputs connects most directly to that ground, and orientate the AC input so that the neutral is most directly connected to ground.

Maven

Thanks Maven, I'll have a look when I get home this afternoon. It's an unusual beast for sure. There is a transformer mounted inside the case, but I'm unsure as to it's role? I thought these sets used a resistor to drop down the voltage? There appears to be a spot for a large high-wattage resistor or similar component on the PSU.

Chris

I've found that the mains lead connects up two two isolated solder strips on the board (which contain only those blue components), which in turn connects directly to a transformer. I'm guessing that the polarity won't be a big issue here, aside from the blue components?

EDIT: I've also located two green 'mystery components' on the main board, with green and brown dots. I have no blinkin' clue what they are now! They aren't diodes, and I didn't find any resistance across them. The two blue ones being on the line into the transformer, I don't know what they would be for..?

Chris

Those little blue components look identical to small inductors as found in 1980's radio's and TV's. If you measure them Chris, you'll find they will have a very low resistance.

Their purpose is to provide some basic noise filtering.

The mains wiring looks to be too double insulated standards so mains polarity should make no difference. From your pictures, the black leads connect to the two red wires via the inductors. Presumably, the two red wires will then go straight into the power transformer.

If the transformer is down the line from the blue components then they won't be diodes. An iron core transformer can't work with DC running through it and would most likely overheat and burn out.

I think the best thing to do at the moment is try and grab a circuit diagram for the receiver. Scan GE circuit diagrams for similar models if one can't be found for that one - they won't have included these just for that model.

TV Collector - My multimeter measured something like 0.1Ω across those components.

Brad - I took a gamble, soldered the two-core mains cable in and plugged it in (using appropriate safety measures in case it went up in a shower of sparks!). It works pretty nicely. I found a replacement speaker (the previously mentioned 16Ω 1.6W speaker), and it works great. Now, I need to fix the LED display (it sometimes displays the wrong digits) and clean the volume pot and AM/FM selector switch. The alarm circuit also seems to be a bit dodgy (the alarm only activates when you touch the switch, so maybe it's dirty?)

Chris

I'd say dirt/dust/grime may well be the reason some of the LEDs are wrongly coming on too. LED displays are sometimes connected in a multiplexed fashion which just adds to complexity.

Could the IC or off-value resistors be a possible cause? I'm going to give it a clean up inside at a later stage, to see if any debris has shorted out the display...

Chris