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Help troubleshooting Luxman R-105 stereo receiver :)

You should try to locate the area of the problem. See the attached pic from your schematic. Can you locate the circled connectors?
Also, do you have a way to play audio out from a phone or computer through this amp?
TRBLSHT.jpg
 
I can only give suggestions as I am not there in person. It wouldn't hurt to check for cold solder joints. Can't even begin to tell you how these will wreak havoc.
 
The traces on that board should be what you see here. (Minus the components which are on the underside)
Tonebrd.jpg
 
Keep in mind the obvious - this is a two channel receiver, and you seem to be reporting a problem with BOTH channels, if I understand your report. You also mention only the headphone outputs. What about the speaker outputs - dead too? How about the tape 'record' output - is there a normal signal there? Have you jacked a known good signal into the AUX in ? (Maybe it IS the tuner.)

Anyway - not many things affect both channels equally, so focus on those that do - tuner, power supply, and as already mentioned, speaker protection circuit.

Can you post a full schematic? And how about describing in detail what you hear as you operate all controls - volume, balance, input selector, tape monitor, etc. This thing is probably whispering clues at you if you listen...
 
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Sorry guys, I had to tune out for a while, something came up. I will go back to it tomorrow and test all if the suggestions above. I will definitely check the connectors first thing tomorrow, as well as look for cold joints. Thanks, GOYA. Not quite sure what you mean by "play audio out from a phone or computer through this amp" ? It doesn't have Bluetooth or USB connections if that's what you mean.

Yes, the problem is with both channels, and with both headphones and speaker outputs. Yes I tried to connect a CD player via Aux inputs and crank the volume all the way up - it's not just the tuner. I did clean all pots, starting with Volume. Volume does increase when I rotate the knob, but it is still very low at the highest setting (i.e. goes from "0" to barely audible). Full schematic is a big file, don't want to use too much bandwidth - it is part of the service manual available for download here. Tape monitor switch works properly - it mutes whatever small signal I'm getting completely. Other input buttons work properly too (balance, bass/treble changes are hard to hear because the volume is so low, but I think are working, input selector buttons all seem to work). Tuner station memory doesn't hold, when I unplug the unit - but I think that's an unrelated issue.
 
I mean a cable with a mini jack that fits into the output of the net capable device and rca connectors on the other end. This is to use an online audio signal generator (or an app). I assume you don't have a signal generator or a signal tracer.
 
OK, I have some good news finally. After pulling the thing further apart (separated all of the boards from chassis), inspecting all connections carefully, cleaning as many things as I could with deOxit and/or alcohol and reassembling, it is now working properly - tuner, Aux, etc - all produce sound at proper volume. I still don't have a clue what was wrong with it - probably just a grounding issue somewhere or a short? I didn't find any obvious flaws or replaced any additional components - just the two large filter caps.

Sound quality is actually pretty good, but noise level is kinda high, compared to my recently serviced (professionally) Marantz 2265B. Any suggestions on how to improve S/N?
 
If it does it again, even on one channel, give the speaker protection relay a tap with something like a screwdriver handle and see what happens....
 
This week I bought online in an estate sale a Luxman R-105 receiver. From the photos I suspect it was stored in an attic or garage as it is pretty dirty. However, the auction says it does power up but it is untested. I paid $17.50 for the receiver, and I will pick it up tomorrow. Like genesmasher, I am a novice at audio equipment repair. I started with some tube mono equipment given to me by my father, who was a radio collector and restorer. But tube equipment is much less intimidating to me than printed circuit boards and solid state.
I will start by cleaning this receiver and then testing it. I will use the schematic listed here in lieu of one for the R-105, and the tips mentioned here for problem resolution if needed. I may start another thread if I document the process, for the benefit of others.
Thanks.
 
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