Luxman R-600 restoration

[Adriatic]

So, bad weather here and I went for the very last action, replacing transistors in tone amp section - and run into issues.
1. Replacing D902a,b with BC640 went good, I even believe that sound had improved (basses do not sound "annoying" anymore)
2. Replacing 901a,b and 903a,b with BC639 -> The sound had improved significantly (high tones became really sweet) - but background noise went horrible! I also had some occasional visual "pumping" of bass driver on my loudspeakers.
I put back the originals and all was good again. Now seeking for replacement for 2SC100 (original transistors are marked BC, 4TC, C1000). Any idea? Would 2SA1815 be the right replacement?

 

[Adriatic]

Ah yes, that resistors on Pentium cooler.. TO-type (1kOhm) doesn't get hot at all - but that ceramic brick (560Ohm) is heating like crazy.. but cooling properly, so all good so far.

Oh man, a simple receiver but really nice playground

 

[Fredrik 1977]

another R600 saved!
nice units, one of my first real hifi amps back in 1991, was 14yo and found one in a dumpster. i was amazed!

 

[Fredrik 1977]

2sc1000 are crap and you replace them with BC639

as allways! when using european standard you have to twist some legs on the transistors.
2sc1000 is EBC, BC 639 is ECB

 

[Adriatic]

Thanks Fredrik, I had few more units on my desk since (Marantz 29, Sony TA-8650 VFET), so never really followed your advice - until today.

I checked the pins on BC639 again. They were placed correctly (I even did that twisting and switched BC with CB but then there was no sound at all).
So, replacing 2SC1000 with BS639 at 901a,b and 903a,b with did improve the sound significantly (probably what you had experienced too) but added some annoying background noise (also when volume is zero).
(placing the originals C1000 back -> the noise is gone, together with the cristality of the sound.

Now, I am not sure how to look further and would appreciate any idea.

 

[Fredrik 1977]

check again. it woult be noisy if EBC isnt right

 

[Adriatic]

So, update on four transistors 901a,b and 903a,b.

Checked again and again, switched pins on BC639 (base pin is easy to determine) -> same story again and again.
Then I got another batch of BC639 AND one batch of BC184B (which were marked as best substitute for 2SC1000) - all with documented pins (and I checked for base pin every time to ensure I'm good).
With them.. you guess -> same same story, significant improvement of sound quality (like opened on all frequencies) but again with background noise (on zero volume).
The problem may be elsewhere whee inserting that noise-free transistors reveal another source of noise. Hm....

OK, then I found NOS 2SC1000 - put them in -> and all was good, very nice and warm sound but not as with bloody BCs.

I am done.. and HAPPY... no more. Love to watch that beautiful face and discrete dimmed scale lights.. just a pleasure to watch & listen.

Next is to persuade my Marantz-collector-very-good-beer-drinking-friend to trade his mint R820 with my Marantz twenty nine

Thanks a lot, Frederik.

 

[Adriatic]

so, Frederik, that restoration kicked on an avalanche.. Few weeks ago I got a present from my friend - nice R-820... and just today a fully working R-1500 found its way to me.

 

[Fredrik 1977]

Nice!

i have a R-800 coming up! but this time im not gonna bother with the resistors. ill do a separate psu for the tuner. like it should´ve been done from factory.

 

[Adriatic]

R-800 has a much better layout then 600, almost like a 1500. You will love it.

 

[Gurkov]

Hey there! @Fredrik 1977 and @Adriatic

Curious to know what speakers you've had good results with, when pairing with the R-600.

 

[Adriatic]

I use Q acoustic concept 20.. but generally not too happy with the sound of R600... all works OK but, once you have 820 and 1500, you do not look at 600 anymore.