Got the set consist of M-120A, C-120A & G-120 (not mk2) as gift from former Boss who's leaving the country. The set has been idle in the matching Luxman rack for several years due to intermittent sound he suspected the amp has problem. Tested at my home that I found it's the preamp has problem and the amp is working perfectly.
After several minutes of playing there's screeching or static sound on both channels at irregular intervals. The strange sound goes with volume control.I'm not a tech so, completely blank on this. Need your technical opinion or insight to at least I have an overview of the problem when I take it to technician.
Would appreciate any feedback you can share...
After several minutes of playing there's screeching or static sound on both channels at irregular intervals. The strange sound goes with volume control.I'm not a tech so, completely blank on this. Need your technical opinion or insight to at least I have an overview of the problem when I take it to technician.
Would appreciate any feedback you can share...
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Could just be the volume control, could be old caps, could be a bad solder joint.
It takes a tech to figure it out. Blind diagnostics is just a stab in the dark. That was the good old days of gorgeous Lux stuff, so have it checked out. All the electrolytic caps are bad by now. Probably dirty switches and pots.
It takes a tech to figure it out. Blind diagnostics is just a stab in the dark. That was the good old days of gorgeous Lux stuff, so have it checked out. All the electrolytic caps are bad by now. Probably dirty switches and pots.
Already did basic knobs test by rotating seems everything is fine, no any sign of dirt in contacts. Not use any contact cleaner and I don't have one. Hope no major problem, have plan to replace the caps. In other thread I read mk 2's C111,C112,C123 & C124 have 2.2uf carps not electrolytic. The model I have at C111& C112 has axial caps with "crossover capacitor" label. Those locations can I put poly caps of same value or only the 2 locations with axial caps.
Thanks for the reply...
Thanks for the reply...
Sounds like bad transistors in the pre-amp or bad solder joints (or both). Does it care which source you're using? Does it stop if you disengage the tone controls? Is it on both channels?
Bad caps are unlikely.
Cleaning the potentiomters and switches is mandatory before you do any kind of service or troubleshooting. This can be the source of any type of problem. Just regular alcohol will work.
Bad caps are unlikely.
Cleaning the potentiomters and switches is mandatory before you do any kind of service or troubleshooting. This can be the source of any type of problem. Just regular alcohol will work.
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Thanks to all..
Will do pots cleaning and see what happens. Used aux input only, others not tried yet.
Will do pots cleaning and see what happens. Used aux input only, others not tried yet.
Spray the MONITOR and DUBBING switches thoroughly, and work them back and fourth about a thousand times (I'm almost not even kidding). These are usually the culprit of many problems, and I've literally experienced the issue you're having with a similar Luxman model which was caused by a dirty tape monitor switch.
This combo is one of the nicest ever made in my opinion. I hope you get it running well (and keep them!). 🙂 If necessary I'd recommend spending quite a bit on them.
This combo is one of the nicest ever made in my opinion. I hope you get it running well (and keep them!). 🙂 If necessary I'd recommend spending quite a bit on them.
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Already sent the preamp to a tech for check up and observation. Gave him all your opinions and suggestions as first stage of diagnosis and trouble shooting. Hopefully to hear from him after a couple days and update here, but still I need your insights for other possible parts need to look into.
Thank to all.
Thank to all.
I got message from the tech, he found the problem on left channel. And it's now running for several hours without any hint of problem but did not mention what's the cause. Will update when I talk to him again.
Have plan to recap the PSU and other signal cap, is it worth to do it? Any recommendation of cap brand and type would appreciate much.
Thanks.
Have plan to recap the PSU and other signal cap, is it worth to do it? Any recommendation of cap brand and type would appreciate much.
Thanks.
Cap type info
Caps @ PCB labeled crossover cap, ? I have Ver. 1 Schematic diagram says 50v 10uf, NX.
if bipolar is it possible to be replaced with poly?
Luxman C-120A mk2
Label: 2.2uf 50v crossover capacitor
Underside of PCB w/ bypass cap
Thanks..
Caps @ PCB labeled crossover cap, ? I have Ver. 1 Schematic diagram says 50v 10uf, NX.
if bipolar is it possible to be replaced with poly?
Luxman C-120A mk2
Label: 2.2uf 50v crossover capacitor
Underside of PCB w/ bypass cap
Thanks..
Those Elna caps that you put in look pretty ancient. Did you put old caps in there? 😱
Bipolar or not, an electrolytic can always be replaced with polyester caps, as long as they fit.
Bipolar or not, an electrolytic can always be replaced with polyester caps, as long as they fit.
Luxman C120A Preamp Recap
Ojojunkie, any further progress on the recap? How much difference has it made?
I have a C120A (not the MKII) but the boards look almost identical from the photos. There are three types of caps in it. In the PS and most other electrolytics are Rubycon. Signal path caps are Elna and there are two Marcon caps C223 and C224.
The unit powers up fine, is dead quiet but lacks the presence and detail of my Bottlehead Foreplay II tube pre-amp. After reading a large number of posts on the subject I decided to give the Luxman a new life and another chance with a recap.
Plan is to replace all Rubycons with Cerafines and the Elnas and Marcons with Silmic II's (again signal path).
Why? People seem to like the Silmics for their smoothness and "tube like" sound while others like the Cerafines, and others, for their detail and punch.
As this is a little subjective, I figured it a good place to start plus it seems like a similar mix to stock but hopefully with much improved components -- and with 30 year old caps, it is bound to be an improvement.
I am likely going to do the PS caps first, then the pre-amp, phono and tone section (I usually bypass this - Foreplay has none of it).
I have photos and a spreadsheet showing the existing complement of caps and the proposed compliment. And can post if there is interest.
Ojojunkie, any further progress on the recap? How much difference has it made?
I have a C120A (not the MKII) but the boards look almost identical from the photos. There are three types of caps in it. In the PS and most other electrolytics are Rubycon. Signal path caps are Elna and there are two Marcon caps C223 and C224.
The unit powers up fine, is dead quiet but lacks the presence and detail of my Bottlehead Foreplay II tube pre-amp. After reading a large number of posts on the subject I decided to give the Luxman a new life and another chance with a recap.
Plan is to replace all Rubycons with Cerafines and the Elnas and Marcons with Silmic II's (again signal path).
Why? People seem to like the Silmics for their smoothness and "tube like" sound while others like the Cerafines, and others, for their detail and punch.
As this is a little subjective, I figured it a good place to start plus it seems like a similar mix to stock but hopefully with much improved components -- and with 30 year old caps, it is bound to be an improvement.
I am likely going to do the PS caps first, then the pre-amp, phono and tone section (I usually bypass this - Foreplay has none of it).
I have photos and a spreadsheet showing the existing complement of caps and the proposed compliment. And can post if there is interest.
firstly, you have to locate where the static is coming from, is it from the preamp or power amp?
you can clean the volume pots with carbon tetrachoride aka "lighter fluid" or deoxit to clear the crackling on the pots when you turn them...
Errrm... carbon tetrachloride is 93% halogen and non-flammable but is a banned substance as a general solvent, due to its damaging effect on our nervous and renal systems and has carcinogenic links too.😱 "Lighter fluid" is a petroleum by-product aka white spirit and burns fiercely but with caution, may be safe to use as a solvent in small quantities in a well ventilated area.
Carbon tetrachloride - Wikipedia, the free encyclopedia
thanks for the heads up Ian, lighter fluid is what i use, in a well ventilated space and small quantities, should not be a problem...i am now 60 years old and seems healthy....just be careful when using...
Well AJT, I'm even older and spent a lot of years in the lab. and factories with solvents of all kinds and the toxicology was well known there, even before I began. The problem was that because the use of carbon tet. and other nasty solvents was once everywhere, even for dry cleaning, the public just accepted it like I did, as a fact of life.
I'm only now beginning to find out what those and many other high chemical exposures like lead oxide, asbestos dust, smoking and sunburn have done over the years. Maybe I should donate myself to medical research
I'm only now beginning to find out what those and many other high chemical exposures like lead oxide, asbestos dust, smoking and sunburn have done over the years. Maybe I should donate myself to medical research