Luxman LV-105u Amplifier - Restoration (Part 1)

The Luxman LV-105u restoration (Finally!)
Enjoy this long winded teardown and rebuild.

[@artharris2537]

I have one of these amps which I rescued from a friend who was going to bin it. It had a few faults - phono stage didn't work, mono button didn't work amongst other things. It was also full of dust where it had been stored in a garage for years. My brother in law put me onto someone who has fixed all the problems and thoroughly cleaned it. He says it's one of the best amps he has ever heard. The cost - £25! He's now looking at my Rotel RA-10.

[@johncooper6246]

Appreciate the fast play in processes. I would've added some muzak but that's just me... Thanks for posting. Most informative, cheers.

[@gustavom8062]

I've noticed the quite unique, mostly European set of test equipment (Metrix and Elektro-Automatik) you use, besides the trusty Fluke. Here in the USA, they are not common and appear expensive. First time I have seen some of them. Great videos and awesome work. Couple of suggestion if I may. I believe you would like a desoldering station; saves time and frustration removing lots of components. I use a Pace SX-80 station and saves me a lot of time. Other options are available, although I am partial to Pace for the ease of finding parts for it. Mine was a slightly used one via eBay as they are pricey new. The other suggestion is, if possible, a bit of the cost related to the overall rebuild of these units. To keep it real for most of the amateur rebuilder out there. Not all amp are worth several hundred dollars in parts. Although personal motives may justify it. Glad to see your quality of work. Keep them coming.

[@whatcouldgowrong7914]

Thanks for the suggestions I will take that onboard for the future :) I generally don't mention it as I'm in Australia and we pay a lot for parts and shipping so it doesn't necessarily reflect the cost but ill add it in. Funny enough my test gear I have sort of stumbled across but yes I'm quite partial to stuff made in Europe or Japan if its new.

[@vintagerider4301]

I repaired a LV-105ut a few years ago and the only item I gave up on was the volume pot, with the center tap for loudness. I could find a few on Ebay or Aliexpress, but none with the same resistance (I think it was 150K or 250K) In the end, I replace the pot with a standard unit, and gave up on the loudness. These days, I just repaired a LV-103 and is is much simpler.

[@sw6188]

The volume pot is 150 k and would have been custom-made for Luxman by one of the big pot manufacturers (probably ALPS) and those parts only supplied to Luxman so you won't find them anywhere else. That said, value isn't critical and you could have used a 100 k in its place without any issue. I have a 105U waiting to be looked at. I bought it not working. I know a couple of the output transistors have been removed. It's been on my 'to do' list for a while but I never seem to get any closer to looking at it.

[@justicelut]

I believe carby-cleaner contains toluene, which would explain why it can remove the glue!

[@whatcouldgowrong7914]

Yup Toluene loves this stuff!

[@Sans_Solo_]

Since electrolytic caps tend to increase in value over time maybe the new filter caps were intended a little insurance policy with the lower (new) capacitance.

[@whatcouldgowrong7914]

The tin foil hat side of me thinks they try to save electrolyte by running on the lower end of the 20% tolerance 🤣

[@ZekiJan]

Where can buy all the caps?

[@whatcouldgowrong7914]

I normally use Mouser :)

[@stef2797]

I don't call that a restoration, it's going to be totally rebuilt, never going to sound the same again.....may as well change the valves for mosfets too.....because there will be nothing original about it.

[@whatcouldgowrong7914]

You’re welcome to get one and leave it original if you want to watch it nuke itself… These units are 40+ years old now and have so many heat related issues. The MOSFETs are unobtainable and if they die due to another component failing, it will end up as a paperweight…

[@stef2797]

@@whatcouldgowrong7914 MOSFETs are unobtainable???...depends where you live everything is full of mosfets these days they more common than transistors.....put a couple of fans in the back to cool it. By the way components like resistors, transistors and diodes shouldn't need changing unless they are faulty the capacitors are about the only things i'd change in that unit, to keep it original, that where it's value is ,collectors don't buy things that have no originality. for reference go here on you tube "Mr Carlson's Lab" he does restoration projects on stuff way older than than your amp.

[@whatcouldgowrong7914]

@@stef2797 Just because they’re called MOSFETs doesn’t mean they’re the same or interchangeable. Many have attempted to use new types in these amps and failed without dramatic redesigns to suit. Not interested in collectors because I don’t resell many of these units. What I want is units that perform as good as or better than new. Things like resistors are carbon film in this units which are noisy and inferior to newer metal films. I’m not chasing a vintage sound, I want a clean sound to suit newer sensitive speakers and headphones. None of these amps sound original anymore anyway. Even transistors become noisy with age.

[@jmqwert]

Hello im restoring old hifi amplifier on amateur basis. One of my bigger headakes is sourcing replacement components. I see that you replace rectifier bridges, diodes, trimmers, capacitors and resistors in signal path. Beside this, dont you replace all kind of latch switches? Regards trimmers, i always try to use multi turn replacements, which is much easier to dial in and gives more stable values. Have placed feed on hifisentralen.no, repairing / restoring an luxman M05 amplifier. Thx for posting these repair videos! Nice use of carburetto cleaning, ill try it out as well!