Luxman M-02 Amplifier Recap

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kecapmanis021

kecapmanis021

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Joined 2017
#1
Hi everyone, my brother has a Luxman M-02 amplifier which has been stored in the attic for like 10 years. I'm thinking of putting it to good use but perhaps most likely the amp will need a recap for the power supply. After I checked the service manual, it specify 15000uF/71V smoothing caps. Does anybody know what brands make that spec? I checked a couple of Nichicon and Panasonic common type but couldn't find suitable caps.

There're also several other caps that baffle me. The Ac type like in C102a,b. What does the Ac denote (what type)?

I don't have background in electronic so most likely I'll get somebody to actually do the recondition. But I'd like to learn and understand more about the amp.

Thanks.
 
#2
Welcome to diyaudio 🙂

Caps like C102 are drawn as bi-polar or non-polarised i.e. an electrolytic that has no polarity and can be fitted either way around.

The big reservoir caps could well be OK if the amp hasn't been abused and subject to 1000's of hours operation at high temperatures. The answer is really to look at the ripple voltage on a scope and possibly try and make a determination of the E.S.R. value. Age alone isn't sufficient to condemn them.
 
#3
Hi Mooly, thanks for the warm welcome. Perhaps I should open the case and see if there's any leaky elco. If all looks Ok then I'll give it a warming up with a cheap pair of speaker this weekend.

I remember the volume pots give a tizzy sound everytime I adjusted the volume the last time we had it on, that was like 10 years ago.

Mooly said:
Welcome to diyaudio 🙂

Caps like C102 are drawn as bi-polar or non-polarised i.e. an electrolytic that has no polarity and can be fitted either way around.

The big reservoir caps could well be OK if the amp hasn't been abused and subject to 1000's of hours operation at high temperatures. The answer is really to look at the ripple voltage on a scope and possibly try and make a determination of the E.S.R. value. Age alone isn't sufficient to condemn them.
Click to expand...
 
#4
The volume controls may respond to careful cleaning with a suitable product (such as Deoxit... but that stuff costs dear). Ideally replacement is the best option for such things or, if the control is of a suitable type, opening and cleaning the track and wiper and possibly re-tensioning and moving the wiper to a fresh part of the carbon track.

Just squirting the controls in hope is the least satisfactory option.
 
#5
10 year old caps should not need any attention, unless they were faulty when fitted or have developed faults due to heavy use. 50 year old caps are a different story. There is no need to blindly follow the herd into unnecessary cap swapping. The most likely outcome is no change; the next most likely outcome is introducing new faults.
 
#8
Today I took off the top and bottom cover of the M-02 and after checking there's nothing leaking/burned. Put the cover back on and switch it on. There's a click sound, I guess it's the delay switch for speaker, the warm-up Led goes out after 4 and half minutes. One thing I notice the left side of top cover is warmer than right side, looking from front panel.

The AC power cord is a 2-lead model and rather thin. My house uses 3 lead AC with one lead for grounding (arde). Is it a good idea to change the power cord with 3-lead cable and if so where should I connect the AC grounding lead inside the amplifier?

For the C-02, the warm-up Led goes out after like 40 minutes, which I think is rather long. This unit also uses 2-lead AC cord. Any suggestion whether I should change it to 3-lead power cord? and where should I connect the grounding lead? Thanks.
 
#9
Make a list of ALL electrolytic caps and replace them for decent quality new stuff. Solves current problems or solves future problems. C02 and M02 are made in 1986 so caps are 30+ years old and worn out if the units have been used normally. I used to repair Luxman stuf but for some reason I mix model numbers up so I can't tell if these are devices that become quite hot. If they do caps surely need replacement. The fact that you have some timing issues speaks words. I have seen many Luxman devices with less than half of the electrolytic caps being OK. Especially the models with PCB's mounted upside down, nearly all caps used to be defective and this was at least 15 years ago ! Maybe the fact that I needed to replace caps in so many Luxman devices is the reason I mix model numbers up 😉 Same for Marantz SC80, I have seen so many defective ones that there was a moment I refused to repair them anymore. With nearly 90% defective caps plus defective semis and shitty PCB material some devices are just meant to be thrown away 🙂

Replace small value electrolytic caps for film types if they fit physically. Make the list and have it checked here if you like. I think you can't go wrong with Panasonic FR.

* Both C02 and M02 can be fitted with IEC inlets with the PE wire connected to the casing in a specified way. Please note that this is best done by an experienced person otherwise you might end up with a less safe and even humming device ! Funny to see that even in 2017 you use the dutch word "aarde" for PE 😀
 
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#11
Hi John. Indonesia used to be Dutch colony till 1942, and "arde" is actually the common term used here for electrical grounding. I think the grounding is an important issue as equipment without proper grounding usually leaks current to the chassis.

M-02 PCB is indeed mounted upside down, a very strange way.

As for the speaker relay, is there any specific type/product you might recommend?

jean-paul said:
Just checked these models and yes, advice to replace all electrolytic caps is sound advice. I know these devices. Also replace speaker relays in the M02 for silver contact ones.
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#13
Yes "aarde" is very important for safety but beware connecting audio-GND to PE. We learnt your kecap manis as "ketjap manis" and even found a way to produce it better 🙂 Also ketjap asin, sambal badjak, sambal oelek and satay sauce can be bought everywhere in the Netherlands. I try to remember the good things and forget the bad things of the colonial period as I am not responsible and I can't do anything anymore to change it. Let's say that the influence of the former "Nederlands-Indië" (tempo doeloe) can still be found in the Netherlands of 2017. We learnt from the Indonesians.

BTW Omron says this type is a direct replacement:

https://www.fa.omron.co.jp/data_pdf/closed/prdn-272.pdf

New for me as I always learnt that a interface PCB is needed. If you can't find the official replacement relays the ones in your last link seem quite OK.
 
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#14
Hi Jean, thanks a lot for the pointer, much appreciated. I'll check out the dimension of the relay unit.

I need to change the power cord since the PVC jacket of the original cord is kind of sticky like rubber going bad. Perhaps I'll just follow the original wiring without AC grounding lead.

I'm glad you enjoy the pun on my nickname. Indeed, there's no need to go into the colonial stuff, let's just enjoy the music. Cheers!

jean-paul said:
Yes "aarde" is very important for safety but beware connecting audio-GND to PE. We learnt your kecap manis as "ketjap manis" and even found a way to produce it better 🙂 Also ketjap asin, sambal badjak, sambal oelek and satay sauce can be bought everywhere in the Netherlands. I try to remember the good things and forget the bad things of the colonial period as I am not responsible and I can't do anything anymore to change it. Let's say that the influence of the former "Nederlands-Indië" (tempo doeloe) can still be found in the Netherlands of 2017. We learnt from the Indonesians.

BTW Omron says this type is a direct replacement:

https://www.fa.omron.co.jp/data_pdf/closed/prdn-272.pdf

New for me as I always learnt that a interface PCB is needed. If you can't find the official replacement relays the ones in your last link seem quite OK.
Click to expand...
 
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