I got my amp as a swap: website for disco kit... i have found that the pre amp stage is fine, it shows both channels on the front of the amp, but it doesn't come out through the left speaker. I have changed all the external wiring around to check if it was that, but nothing has changed the situation. On closer inspection inside, i found a wire that had come loose, which i have soldered back on. I have also inspected the base of the main board and all seems ok.
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Re: Left Channel Not Working
You may have blown the power output amplifier on the left channel. This is what this looks like. You will have to take some measurments to determine if the output power amplifier is indeed malfunctioning.
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Yes amps buzz when something gets near them - say a pen or probe and if you know what it is safe to touch a finger! Fortunatly for you the left channel is the same as the right. So if you believe it's the pre-amp work backwards from the where the power amp connects to the pre-amp, going through the pre-amp stage by stage - prodding the parts. Remember a buzz in the right a buzz in the left! No buzz in the left but one in the right fault found! Ignore the power supply it's nothing to do with that as it's common to both channels.
Hi there I have a C340 that has similar problem, you must have bought this from ebay, lol.
Nad made a mistake on the C range, the pre - power link can be shorted out. if the pre is shorted out it takes out the pre amplifier stage, I have managed to get the right channel working, I will keep you informed what is the cause of the left channel. I have replaced the pre-amp IC and a couple of Jfets and transistors. Once I have repaired the Amp I could repaire yours if you like???
To find out what the problem is try this, swap over the right and left leads from the deck to the amp. If the problem stays on the left channel there's something wrong with pre-amp in your amp. If it goes to the other channel (right dead) it's the deck. Next remove the wires to the cartridge to the deck with the fault. Make a note of how they fit on the cartridge before you do. With the amp connected to the deck and on. Touch (one at a time) each of the four wires with your finger. Two of them will probably produce no sound. But from one wire you should hear a buzz on the left channel and from another wire a buzz on the Right channel. If you get a Buzz on the left speaker then all the connects are good and the cartridge has gone. If you don't get a buzz, then there is something wrong with the left cable connector between the deck and amp.
The left channel output in the amplifier stage is going out - could be a cold solder connection due to overheating. Check the left channel output of the power transistors solder trace - you can compare them to the right channel stage because they're almost identical circuits.
The mono button on your amp is simply feeding one channel to both sides, so is no indication that the other channel is working. Here's what to do. With the good channel comming off your deck, swap it over so it's going in the dead channel side on your amp. If the channel does not spring into life, it's not the record deck that is faulty, but your amp. Now your thinking but it works on CD! True, but the record deck socket on the amp has another pre-amp just for that purpose only. You can track this pre-amp down by following the wires from the socket.
If on the other hand the dead channel comes to life when you swap the jacks around, then it's is the deck. The most obvious fault being the cartridge. But some decks also have a pre-amp in them.
More likley that there is a fault in either the pre-amp or power amp of the left channel. To be honest with you it's one of the most diffcult problems you can have, unless you can see a burnt or damaged part. All you can do is compare the parts in the right channel with those in the left.
Touching the parts in either channel with a screwdriver (don't short any) will cause a buzz! This can be used to test the channels. Work backwards from the power amp section. Remember a buzz in the right should give you one in the same place on the left!
PS KEEP AWAY FROM THE POWER SUPPLY.
If you are not good with electronics consult someone who is.
If amp has pre out power in connections the try driving another amp from pre out stage. Try driving power in stage from another source. Swap round inputs to check preamp section Always start at low volume, check sound is ok at low the make it loud.
Write down results of all tests, it will save time and money at the repair shop
It sounds like the preamp wire that carries the left channel signal between the HU and the 2ch amp has an issue. Here's two quick things to check.
Check that both ends of the left preamp cable between the deck and 2ch amp is not loose or disconnected.
Swap the left and right preamp connections at the amp. If the issue stays with the left channel, the issue is with the amp. If the issue moves to the right channel, the issue is with the preamp cable or the HU's preamp output.