Luxmann L-410 problem - noise

EE · 27th August 2009, 02:20 AM

Hi everyone,

my old Luxmann L-410 is suddenly making problems.

Its idle noise has slowly increased over the last weeks... I can now clearly hear a hiss in my listening chair, about 3 metres away from the speakers. It has been dead silent before. Also, it has become extremely sensitive to other devices being switched on or off. Everytime the fridge goes off next door, I can hear a loud "click" and see the membrane of the woofer move outwards. The same happens when I switch off the lights somewhere in the room. Sometimes it "clicks" with no appearant reason - could it be that it's also sensitive to what happens at the neighbour's flat?!

I am absolutely sure I didn't change anything in my setup. Also, I checked whether the problem remains with the volume turned all the way down and with all cables removed except mains and speakers - it does.

Any idea what could be wrong? Is this old amplifier dying?

Regards

sakis · 27th August 2009, 05:43 AM

you might have mecano issues loose contacts or grounds
you might have recaping issues ( small electrolytics are dried out inside the amp )
you might have cleaning issues switches and pots inside are dirty or very dirty

take a look at this .... a vintage amplifier repair and upgrade manual
vintage amplifier repair/upgrade manual

hew128 · 2nd September 2009, 01:44 PM

Hi EE,

Sounds like a similar problem my L410 had. Additional "problem" was when I push the SPKR-A/B button in, there was a loud sharp thud sound. Was also super hot when it was on. Had a electronics burn smell as well - bad capacitor and the transistors.

Sent to a local repair shop twice and now works like new!

Problem was solved for my L410 when all the transistors were replaced. I recapped it myself and now works like a treat w/o the bad smell.

tricomp · 4th September 2009, 08:33 AM

Hi,

At least you could investigate if the problem (Hiss) is comming from the pre- or the mainamplifier.
As I remember the L410 has a Pre-Out / Main-In provision that can be bypassed with a switch. If you have nothing external connected between the OUT/IN RCA's your switch must be set for the bypass mode. Put it in the opposite position to disconnect the pre-amp.
Did the hiss go away? If so, obviously you should look in the pre-amp section for the fault. If there's still noise, the main-amp is defective. Could be bad electrolytic cap's, could be any transistor, could be .... well, your guess is as good as mine.
..only MY guess during a repair would be founded a bit on looking through the service-manual

PM me with your e-mail address if you need more info.

/rgds,

/tricomp

27th August 2009, 02:20 AM	#1
EE diyAudio Member Join Date: Oct 2003	Luxmann L-410 problem - noise Hi everyone, my old Luxmann L-410 is suddenly making problems. Its idle noise has slowly increased over the last weeks... I can now clearly hear a hiss in my listening chair, about 3 metres away from the speakers. It has been dead silent before. Also, it has become extremely sensitive to other devices being switched on or off. Everytime the fridge goes off next door, I can hear a loud "click" and see the membrane of the woofer move outwards. The same happens when I switch off the lights somewhere in the room. Sometimes it "clicks" with no appearant reason - could it be that it's also sensitive to what happens at the neighbour's flat?! I am absolutely sure I didn't change anything in my setup. Also, I checked whether the problem remains with the volume turned all the way down and with all cables removed except mains and speakers - it does. Any idea what could be wrong? Is this old amplifier dying? Regards

27th August 2009, 05:43 AM	#2
sakis diyAudio Member Join Date: Jan 2006 Location: nea makri athens greece	you might have mecano issues loose contacts or grounds you might have recaping issues ( small electrolytics are dried out inside the amp ) you might have cleaning issues switches and pots inside are dirty or very dirty take a look at this .... a vintage amplifier repair and upgrade manual vintage amplifier repair/upgrade manual __________________ SERVICE ΕΝΙΣΧΥΤΩΝ ΚΑΙ ΙΑΠΩΝΙΚΩΝ ΜΗΧΑΝΗΜΑΤΩΝ ΗΧΟΥ www.eastelectronics.gr

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2nd September 2009, 01:44 PM	#3
hew128 diyAudio Member Join Date: Jan 2006 Location: Singapore	Hi EE, Sounds like a similar problem my L410 had. Additional "problem" was when I push the SPKR-A/B button in, there was a loud sharp thud sound. Was also super hot when it was on. Had a electronics burn smell as well - bad capacitor and the transistors. Sent to a local repair shop twice and now works like new! Problem was solved for my L410 when all the transistors were replaced. I recapped it myself and now works like a treat w/o the bad smell.

4th September 2009, 08:33 AM	#4
tricomp diyAudio Member Join Date: May 2004 Location: Jutland	Hi, At least you could investigate if the problem (Hiss) is comming from the pre- or the mainamplifier. As I remember the L410 has a Pre-Out / Main-In provision that can be bypassed with a switch. If you have nothing external connected between the OUT/IN RCA's your switch must be set for the bypass mode. Put it in the opposite position to disconnect the pre-amp. Did the hiss go away? If so, obviously you should look in the pre-amp section for the fault. If there's still noise, the main-amp is defective. Could be bad electrolytic cap's, could be any transistor, could be .... well, your guess is as good as mine. ..only MY guess during a repair would be founded a bit on looking through the service-manual PM me with your e-mail address if you need more info. /rgds, /tricomp