Question about Lexicon MC-1 Amplifier

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Volume has started to fade

I have a Lexicon MC1 which has been working fine for the last 6 years. it was properly setup by a specialist. Recently the volume has started to drop to zero on its own accord and has to be put back up manually. Other times when watching movies the sound goes all fuzzy and the only way to hear anything meaningful is to put it on 2 channel. DTS, THX 5.1, 7.1 all sound awful. Any ideas?

Any assistance would be greatly appreciated.



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  • DannyPara May 29, 2008


    Many Thanks for the prompt response. I have access to a good solderer but how will I know which joints need re-soldering? I haven't opened up the case yet to take a look but I can guess that there will be a lot of electronics in there.

    Many Thanks again,


  • DannyPara Jun 02, 2008


    Many thanks for taking the time to assist me. I still need to find the time to get the unit to an Electrician in order to get the soldering done. I will report back once that has been completed.

    Your help is greatly appreciated.



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HI DannyPara

If the problems are intermittent, then the amp will most probably be suffering from dry solder joints. This is not uncommon about power devices in the unit like output stages and power regulators. I suggest that the amp needs to be checked over for such problems, and where needed resoldered to bring it back to a reliable state. If you are a gun with a soldering iron, you could do it your self. For this sort of work, I prefer to use solder with a 2% silver content as it produces a mechanically stronger soldered joint, and has a higher resistance to failure from the rigours of heating and cooling that constantly happens in amplifiers. If you think you dont have the skills required(good quality soldering is an practiced, and aquired skill), then get it into a decent repair guy for some attention. If you dont fix these problems,new faults may manifest themselves, and even expensive failures to output stages if left unattended.

Happy to answer any other questions you may have about it, just give me a hoy :) Thanks for using FixYa, If you consider the advice I have given you as sound, a FixYa rating is a great reward for my efforts to help you. Cheers.


Posted on May 29, 2008

  • Graeme Ross
    Graeme Ross May 30, 2008

    I would start with the power supplies, and audio power output stages. Any area that has has heatsinks, or where browning of the PCB is occurring, or just plain suspect looking joints. I also like to spend some time thouroughly inspecting the soldering of the PCB's under good light.

    I have a term that I use to describe this sort of work. BLANKET RESOLDERING. Pretty much means resoldering everything that may need it, or even not need it. Failing solder joints can be very difficult to find with the eye. You can often test for these sorts of problems by heating areas with a hair blow dryer(dont get too carried away with the heat), and then gentle repetitive tapping of the PCB in that area may help to locate the section that is contributing to the problem, and help to prove that you have indeed fixed it. The same percussive technique can isolate the problem whilst the unit is actually faulting also. Good Luck :) Let me know how you go. :)




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