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Need Luxman Help!  M-120A Amp
Need Luxman Help!  M-120A Amp
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Old 9th April 2004, 12:31 AM   #1
Thinkster is offline Thinkster  United States
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Default Need Luxman Help! M-120A Amp

I've had this classic Luxman Amp (M-120A) that's been out of commision since 1995! One channel was blown and the other channel was weak output. Replaced the four output transistors for the blown channel and tested it out only to have the replaced transistors blow out again! The load was fine, it was on a test bench so the output was not shorted. Back in 1995 I was not able to find a service manual or schematic or even the company Luxman for that matter. Now it's time once again to try to get this Baby running again, so If anyone has a schematic, service manual or advice, that info would be highly appreciated. I don't have the time to reverse engineer it, that's why I need the schematic...

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Old 9th April 2004, 03:03 AM   #2
K-amps is offline K-amps  United States
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1) What are the outputs? If Toshiba 2sd424/ B554 then I have the original Tos parts.

2) Replace the bias transistors on heatsink and the drivers/ pre drivers.

3) Power up with 100 watt lamp in series with AC promaries, this will save any further output destruction.

Good luck!

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Old 16th December 2004, 08:24 PM   #3
Punitg is offline Punitg  India
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I do have the document you are looking for. I want to help you since I have the same amp but sad not using it. Would like to know mor about you, do send me mail 10
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Old 16th December 2004, 10:10 PM   #4
EchoWars is offline EchoWars  United States
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Originally posted by K-amps
1) What are the outputs? If Toshiba 2sd424/ B554 then I have the original Tos parts.
Good to know...I might have to pester you sometime in the future.

The Lux 120A uses plastic output devices (2SC2581/2SA1106, TO-218 package) on a heatpipe. I have the manual somewhere...but rarely do the outputs blow without taking something with them.

The lamp is mandatory for repairs and an excellent suggestion (unless you can afford a nice Variac...)
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