Giving this another shot...Labtec LCS-2412

Good luck. I would venture to say it is going to be next to impossible to find service literature on things like your speakers which likely would never get serviced by a third party facility. I've come to terms that for many items there is just no service info available unless you are a factory authorized repair center.

I'd give it up, myself. That kind of unit is unlikely to have anything very complicated inside anyway. If you're really set on repairing them, buy a few 'chip amp' kits which use the same supply voltage and substitute those for the original circuitry. Couldn't cost more than ten or fifteen bucks. If you can ID the particular chip amps contained in the original circuitry, buy a one of the chips and sub it out. There's very little else to go bad in such gear.

jak

Yeah, that was the answer I sort of expected, but I thought I'd give it one last try. Thanks for taking the time to reply.

This unit uses multiple-op-amp DIP chips. If one or both channels were completely dead, I think I'd be in better shape from a troubleshooting perspective.

But it's exhibiting some weird behavior: the volume control works normally for the right channel, but the left channel output level remains very low as you rotate the knob. During roughly the last 20% of the rotation of the volume control, the left channel output level will "jump" up to match the that of the right. I've cleaned all the pots.

The (single) tone control increases the treble of the right channel properly, but the left channel remains "muffled" until again you approach the maximum treble setting, at which point the left channel emits a soft thump followed by a constant, quiet hiss that sounds like pink noise - almost as if the tone circuit is entering into hard oscillation at a frequency higher than I can hear.

I guess my best bet's going to be to find some typical circuit diagrams involving the same chips, and use those as a troubleshooting guideline.

Thanks very much for the reply.

Unless this is some digitally controlled complex audio system, and suspecting it is a set of conventional "computer speakers", why not do what we all must do from time to time; open the devices, remove the PCBs and trace the schematics. Often the time incurred is less than the fruitless efforts at searching for the schematics elsewhere.

Regards,

Michael

I thought it would be worth one more attempt at acquiring a schematic, before I begin doing exactly what you've described.

Thank you for replying.

Sorry I didn't have better news. But spending a majority of my adult life as a tech I have experienced your dilemma countless times and spent countless hours searching for solutions fruitlessly.