Luxman - Early saturation on negative cycle

[canonnica]

Hello,

I would like to have some clues on this problem. I have a Luxman R-113 integrated amp that shows a kind of early saturation on the negative portion of the sine.

Although both channel shares the same power rails, this problem is only present on one channel.

I guess the problem resides either at the driver or at the output transistor. Interchanging the components from one channel to the other may guide me to the faulty component, but from your knowledge, where should I start?

I also have the schematic.

Thanks for your help,
Martin.

 

[east electronics]

well Luxman pcb of that era suffer from poor soldering , dry soldering , and some thermal issues that might result to balance issues

Let also not forget that the unit is quite old so count capacitor issues and even resistors drifted from overheating or moisture .

Fusible resistors might also drift especially in the areas of TR518,528,536 and so on ...measure voltage drop across them to see but also measure voltage drop between identical points between L-R ch to target the failure

kind regards
Sakis

 

[TANDBERGEREN]

Check the power supply for the driverstage, as faults there will cause such problems.
(TR528, TR522 etc.)

And Yes, You should check both the positive and the negative line.

 

[east electronics]

yeap ...i ve missed that it can also be a loose connection issue ...rear but not impossible

kind regards
sakis

 

[canonnica]

Sakis, you were right. The R586 fuse resistor seems blown, the voltage drop across it is 17v. It's resistance if of 10k instead of 2,2r. The other channel is ok...

Do you think it's a simple failure of the resistor or the tr536 could have failed? The latter would be surprising as there is a signal at the output.

I guess that changing the r586 would be the first step and see what happen...
Thanks!
Martin

EDIT: i've "piggybacked" a 2.2r resistor over R586 and the output is all good. No other component seems wrong...

 

[east electronics]

well done .... check for more ...

Kind regards
sakis

 

[destroyer X]

Some guys thinks they are good...you see the one is good

Some think.... imagine...some are really good.

This Greek sniffes troubles.... detects things with precision.... knows everything about audio...knows all brands and almost all defects.

What is the brand you like the most dear Sakis?....and why you appreciate that brand/model the most?

Great Sakis!

regards,

Carlos

 

[east electronics]

in a nutshell: simple things tend to play always better ....i could go for accuphase some luxman some marantz some perreaux may be

make any amplifier you like keep it simple preserve the audio rules as given in the forum for so many years now and it will play like hell

kind regards and a few barks uncle Charly !!
sakis