Luxman R-1030 no audio

[Jarekw]

Hi, I have some experience with electronics but I'm new to fixing vintage receivers, I have Luxman R-1030, and no audio from any input. When in AM/FM mode I can see the tuner is working, 10mV DC offset, no burned elements, I can trace the signal past volume control. I think I'll recap the power supply next, any other suggestions would be much appreciated.
thanks,

 

[mbz]

Will dig out the sm, both channels out would point to the power supply, I wouldn't rush with the recap, best to sort this issue out first. Test for audio at the input to the power amp stage, just before the differential pair (transistors)

EDIT test for audio at R403(L) and R404(R), either side of the resistors, will look at psu

EDIT Mesaure dc voltage at R352, expect about -30Vdc

 

[petes'picks]

Clean the switches, especially the tape monitor switch. Check the 2 fuses on the board below the tuner flywheel.

 

[Jarekw]

I tested all the fuses and cleaned all switches, will check for audio on R403/404 and voltage at R352, thank you for all the replies so far

 

[Blue Shadow]

I wouldn't rush with the recap, best to sort this issue out first.

QFT

 

[Jarekw]

the voltage on R352 is -31.1Vdc and -27.4Vdc on the other side

 

[mbz]

the voltage on R352 is -31.1Vdc and -27.4Vdc on the other side

Looks ok, test for audio at the power amp inputs, ie,

test for audio at R403(L) and R404(R), either side of the resistors,

assume you have an oscilloscope which will make things easier

 

[Jarekw]

Quick update, I traced the signal to the base of transistors Q301 and Q302, but it did not pass through, no voltage on the collectors, I found the resistor R 351 was open, tested Q1-4 without removing them from the board, and it seems ok. Should I remove them and test? checked all resisitors in the same circut, all seems ok, I wonder what could cause R 351 to burn out.

 

[mbz]

I wonder what could cause R 351 to burn out.

Good question, should always be asked, yeah a short in the area of Q301,2,3,4 would explain, assume you don't have a solder bridge.
Replace R351 then DBT power up, remove DBT/normal power up if bulb dims as expected.

Should I remove them and test?

In circuit testing can be misleading, I'd replace R351, DBT power up then check b/c/e voltages to GND for these transistors, making sure there is no short, voltages will be a bit low because you are on DBT, if transistor voltages look ok (no shorts) then remove DBT then normal power up/test.

 

[Jarekw]

I got a new resistor and made the DBT, powered up, everything looked good, checked dc voltage, no issues, connected speakers, and ... pleasant surprise, got sound from the tuner and aux, so happy! I'll clean it and post some pictures after. Thank you for all your help!

 

[002]

Thanks for this thread. I had a Luxman R-1030 on the bench yesterday with the same symptoms as yours and R351 was open. R352 was also open and a bunch of the same type of resistors on the tuner board were kaput. I think it must be some manufacturing issue because literally all of the white resistors stood off the board were bad in my case, and I'd encourage others to check them if they have this same receiver.

On a side note, the R-1030 is very much to my taste aesthetically.