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Vintage Luxman L-450 crackle and hum

Hi All - I'd be very grateful for your thoughts on a disturbing new development. This morning, after a nice and not very loud listening session, I stopped the last song and noticed that all was not quiet. The amp, a Luxman L-450 in pretty good shape, was making a kind of static-crackle hum, not very loud or low — like maybe middle C on a piano. I turned the amp off and back on: still there. I switched between all of the inputs (aux, phone, tape, etc.) and it was still there. Volume and tone controls had no effect. (It did not get louder when I turned up the volume.) What could it be? And what's the right way to repair it? I really like my Luxman and I want it back in shape!
brooklynluke
czarivey
5,946 posts
 
pro audio repair in Crown Heights
teo_audio
2,197 posts
 
Switches will also be an issue. Lube-cleaning them is generally a short term solution.

As in we hope we get lucky but no one has ever managed to be in that 0.5% (or whatever it is) percentile of people who somehow have all clean non-oxidized switches after 30-40 years.

I take them apart and clean the contacts with 3000-4000 grit sandpaper, to remove the oxide build up, the kind that never really comes off with any 'treatment'.

It's a huge job, at best. Not worth it for the the average person, unless they want to keep the item.  No one would every pay for the work, it's labor, labor, labor to the max. $400-500-600 labor on a $300 integrated? Yes, very possible. This is very much a DIY thing, not for the faint hearted.
czarivey
5,946 posts
 
switches and knobs are noisy when disturbed which isn't issue of current discussion. noise that comes without disturbance of knobs and switches is coming from circuit components.

teo_audio
2,197 posts
 
yes.
minkwelder
255 posts
 
Many of the problems on the Luxman units of that vintage were due to the thermal breakdown of integrated circuit modules (DML's) that are no longer available. There is a guy in, I believe, Holland named Hans Hilberink that makes replacement modules that are supposed to be better than the originals.

One of the best guys in the states for Luxman repairs is Tom Ishimoto at Northridge Audio in California, but Hans probably knows of someone closer to you. Hans posts on the Luxman Yahoo group, and is a goldmine of info.
http://www.hilberink.nl/codehans/luxman.htm
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