Luxman L100 redo.

anderslober

Yikes...not again!
I have a Luxman L100 here on the bench now. WOW....IS IT JUST ME....or is this amp horrendously complicated?
The amp is a nightmare to take apart.......only the amp section is easy. No worries.......still looks like a nice amp.
It is choke-full of 2sc1345 tr's..........will ksc1845 suffice? I have seen a couple of other threads where BC550c is recommended......I don't have any of those. There is a slight difference in voltage and amperage..............and hfe.......will this be an issue?
The amp is also full of tantalums....I have never seen so many before...........
Also , the amp has a few vd1221 diodes......2.in-series 1n4148 will go in instead.
The SM is also kinda' funny.......the parts list and the scat dont always correlate...many 'mistakes'.......should be fun!
 

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PS done. New caps, a couple of resistors changed, new relay.....
 

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Cohibajoe.....I have actually been looking into your thread. Great info.
I am waiting for some caps to arrive for the amps.......then I should be ready for a power up test.......
This unit was in poor shape from the get go.....cut wires, missing outputs, missing caps....with the help of a few threads here on AK and the (poor) SM, I think she will sing soon!
 
I managed to get the L100 running. Although, I still have a couple of sniggles. Right output is lower than left. When I flip the Reverse-Stereo-Mono switch to Mono, I get very low output in both channels. Almost like a mute switch does. This isn't normal is it?
I have changed ALL the 2sc1354 's to new ksc1845(yes...pinout different...doublechecked)
I have cleaned all switches multiple times. The main volume is a sealed type.

Bias and dc-offset are set to spec.....60mA (removed the jumper wire at test point) and 0v (at speaker terminals).

I also attempted to test where the fault was using another amp(Marantz 1070). When I used the L100 as preamp.....the above problem was evident. When I used the L100 as amp, I got a loud hum/buzz.......scared the heck out of me! Any ideas? Something to do with the L100's funky touch-mute-volume-thingy......?
 
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After reaping and repairing a couple of the Lux suck faces I feel your pain. Quite possibly the least serviceable equipment.
 
I getcha'...I am not to impressed either. Fantastically complicated amps.
Anyway......I changed all the 2sa640 's on the flatamp and tone amp to Ksa992 .
I still have the distortion/scratchiness/low output on the right channel. The amps are confirmed ok. I just dont know where to look now.....
Orientation of caps and tr's has been checked and rechecked multiple times.
Could it be just a case of dirty switches?? I have thrown all switches hundreds og times.................Now that I have the amp in pieces again, I will re-clean the switch board.....hard to get to!
When ever I throw the LOW CUT switch, I get a slight 'tick'...........
Any ideas?
 
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Ok......as I always do when a problem like the above described pops up...I start poking around all over the place. Concentrating mainly on the preamp. I think I may have found something......it has to do with the relay circuit/touch mute area on the preamp board.
I can get the sound to come in strong on the right when poking around the relay.......

According to the scat', the signal comes from the MAIN IN....routes through the touch/relay circuit......goes through the attenuator and then to the amps.....
In the above mentioned circuit are some 2sa733 's and 2sa945 's......could one of these tr's acting up cause my problem?

Are the type of relays available? Small and flat types...12v.....may just change that too.

Gettin' close now!
 
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I think I may have a switch problem..:-(. There is definitely something going on with the hi/lo filter switchs.....I can get the right side sound to disappear/reappear by flipping them. There is a slight 'tick' through the speakers too.

I need Kale' s skilles now.......HOW the heck would you clean this type of switch? I squirted deoxit all over and in'em......but I still have a feeling it ain't enough....
 
Yeah....I just desoldered all of 'em.....fiddle fiddle fiddle fiddly job! Now the switches will be washed in deoxit!
 
Man, I am at the end of my limited wits. I desoldered the switches.....drowned them in deoxit...reinstalled all of them......I still have the lower/scratchy output on the right channel.
I have confirmed that it is somewhere in the preamp section. I swapped the amp input signals and the problem moved to the left. So, the amps are fine...excelent output and bias/dc-offset is set to spec.
So my problem lies somewhere BEFORE the signal enters the amp.
When I look at the block diagram, there are a few 'timing' sections........where are these 'timing' sections? Specifically, where is the 'time muting' section just before the MODE SELECTOR A/B? This is the only place where the signal passes through (and the flat-amp) when all controls are in bypass(off).
 
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Ok......as I always do when a problem like the above described pops up...I start poking around all over the place. Concentrating mainly on the preamp. I think I may have found something......it has to do with the relay circuit/touch mute area on the preamp board.
I can get the sound to come in strong on the right when poking around the relay.......

According to the scat', the signal comes from the MAIN IN....routes through the touch/relay circuit......goes through the attenuator and then to the amps.....
In the above mentioned circuit are some 2sa733 's and 2sa945 's......could one of these tr's acting up cause my problem?

Are the type of relays available? Small and flat types...12v.....may just change that too.

Gettin' close now!


Could be a bad solder, or even a broken trace.
 
I checked over all the solder that I could.....looks ok.
The thing is, that I can get full sound back in the right channel by fiddling the switches multiple times. Mainly with LOW CUT and STEREO/REV/MONO switch. They are super clean!

I even desoldered the small 12v NF2 relay and cleaned its contacts. Are these types of relays readily available?

I am starting to hate this amp! I am so close, so close.........:-(
 
With everthing set to normal/OFF......aux1 used.....by pocking the relay on the TONE board, I can instantly make sound become normal in the right channel. Could it be the relay itself? All caps, tr's and diodes are new in the area.
I need some inspiration......
 
Well....I fiund out the protection works as it should! :mad:

Apparently the phono EQ is throwing out DC!:sigh:

I switched input with the selector and there was an almighty THUMP/Scraaat!!

Unit went into protection.... I switched back to AUX....unit came out of protection again.....so, still not done I guess:thmbsp:

I didn't change any tr's on the EQ amp. Sigh....probably should have.

Any good subs for 2sa606 / 2sc959 ..... Metal can type.......I dont have any. Any ideas? Thanks.

Edit: I have some ksc2690/ksa1220... They seem close in spec.........use?
 
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I totally redid the phono EQ board. All new tr's and diodes. Shucks.......the problem still persists.
The only thing phono input and aux input have in common is the relays.
Luxman outdid themselves with this system. The signal passes through 2 relays.....nf2 and nf4.....it passes TWICE through the nf4.
I am going to change the relays. If this doesn't cure the problem........then I need a straightjacket!!
 
Make sure all your earths are connected.
I had the same problem in an old Marantz amp. it would go into protection whenever you changed input source. there was a main earth wire not connected from the preamp board.


I totally redid the phono EQ board. All new tr's and diodes. Shucks.......the problem still persists.
The only thing phono input and aux input have in common is the relays.
Luxman outdid themselves with this system. The signal passes through 2 relays.....nf2 and nf4.....it passes TWICE through the nf4.
I am going to change the relays. If this doesn't cure the problem........then I need a straightjacket!!
 
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