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Luxman LV 105 Amplifier gone dumb

Hi there,

I have a Luxman LV 105 Amplifier that sudden gone dumb. It is one driven buy both tubes and FET's. I open it up with power on, I found:
the LED's on the board glow,
the heat sink warms up,
and the tubes, visible from outside, glow too,
no hissssssss from any input gangs (phones, tapes, aux...) even with volume control turned to max.,


Can anyone suggest to me what might probably gone wrong and where I should start to probe the problem?
Can anyone offer me a copy of the maintenance manual?
(note: this model is 220v. Version LV 105, not LV 105u of which I have a copy).

Posted by on

  • mayfirst Mar 24, 2008

    Thanks to Guest who sent me the Rapidshare link to download manual. It is the one I need, with 2 power transformers.



    But still though, would appreciate some one who can tip me on where to start probing the problem.



    I further found out that both heat sink and FET's, R Channel was hot, and L Channel (L side of heat sink) just warm, probably warmed up by the R.



    I am not too familiar with FET's.

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4 Answers

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Hnfgdgd

Posted on Mar 24, 2008

  • P1stol Mar 26, 2008

    Hey, it would be best to replace all the FET's and transistors on the main pcb and the pcb under the main pcb. This is wat i did.

    use this site for parts. comes to around 60$. http://www.audiolabga.com/

    parts i used where;

    2sk1529 x2

    2sj200 x2

    2sa1321 x2

    2sj75 x2

    2sa1360 x4

    2sc3423 x10

    2sc1815 x6

    2sa733 x2

    2sc3378 x2

    2sa970 x1

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Hi: If the Amp has an audio output transformer, check for bad solder connections to the pc board, This are the wires from the transformer to the PC board. Another place to look is the earphone connection plug. If the jack has a bent contact inside of it, you will have all sound cut off. Good Luck.

Al

Posted on Mar 13, 2008

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  • Master
  • 1,175 Answers

Dumb questions first...

Is the Tape monitor on?
Speakers properly connected?

Less dumb questions..

The tubes have high-voltage on them . Upwards of 450VDC.

DO the proper voltages appear on the high voltage pins on the tube sockets?

AND WATCH OUT FOR YOUR FLESH coming in contact with HIGH Volts DC . It can cause death.

If the only difference between the LV-105 and LV-105U is the line-in volts then you can use the 105U schematic for everything after the power transformer.

Posted on Mar 10, 2008

  • Scott Frye
    Scott Frye Mar 25, 2008

    If the schematic shows what voltages should appear on the power fets and the fets measure OK then fets getting hot should be replaced.

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