Luxman L-100

Hi Dear Friend & Experts,
Finally I replaced all transistors of driver PB 649.
Seems ok. Relay ON after few seconds but now Mute is continuosly not working either touch again and again but no output. Please guide how to do next. I will be thankful to you.
 
Hi experts,
I am repairing Luxman L-100. There are two driver circuits L649 for each channel driving the power transistors. A power supply that is 55 volts DC feeding to these circuits. When I pull up the connector of one channel supply, Left Channel or Right channel it works only that channel which has power supply but once I put connector of both channels, front light keep on flashing. Only one channel at a time. If anybody guide me, I will be thankful to you. Waiting for comments from experts.

Yes, I swap both Channel's power stage but behaviour of amp remains same. This is clearance indication that something wrong with the power supply. It has not enough power to drive two channels together.
Hey this is 1st time nice to see a member from my country.
 
Ok. Understand.
It has two metal links. I will link them as you suggested. My question is that, will it has some link with Touch Mute button. I bypass this system by removing the collector of related transistor and make the ground jump to relay. Then relay gets ON and the LED also lit up. Even then there is no sound. I am out of my lab for three days. One I join that then I will share the circuit diagram how I bypass the touch mute circuit in the PCB. All three relays gets on after some time and blinking of front LED stops. Anyways really thankful to you for your guidance.
 
Dear Mark,

Thanks for the guidance. Actually fault traced. Referred to Power supply PB647 the connector C07S ...C10S is not generating +- 55 volts reference to ground .
As the variable on the same power supply VR901 & VR902 have no effect even if rotating these. Do you have any clue to get required voltage. Where as all the components are tested and are ok. I think some trigger signal like power good signal initiate these volts from the driver cards PB649 connector C11M ... C18M. Please guide if you know with thanks.
 
I unable to understand that why the power supply is som complicated. Power transistors are derived directly and PB649 the driver stage is through regulated power supply from PB647. Very complicated. In present condition DC of -2.9 volts are going directly to speaker terminal. No separate protection circuit or speaker crowbar protection.
 
Okay, I think I see where you are looking. Its the same area we discussed back at the beginning of this thread, including the circuit description in the service manual. Its around post #30 of this thread. https://www.diyaudio.com/community/threads/luxman-l-100.412994/post-7691761

I would suggest to go back to that post and to the service manual on page 6, and study what it says. It includes a start-up circuit that has to be working for the power supplies to come up. You shouldn't have turned the voltage regulator pots. Now if you get the power to come back on, the voltage may be too high and cause more trouble. I would suggest to set the pots to the middle of their range to start with. The check the start-up circuit. Is it starting up.

Anyway, you need to read the manual and try to understand the power supply circuit. If you try to understand it and you have specific questions, then I and perhaps others will try to answer.

Beyond that, the power supply isn't that complicated. Also, its unlikely that both the + and - supplies would fail in exactly the same way at the same time. Maybe you should focus on the startup circuit to begin with.

Go back at read the posts at:

Didn't you at one time get it to start up using 4.7k resistor? If so, then why screw around with the voltage adjust pots?

 
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I unable to understand that why the power supply is som complicated. Power transistors are derived directly and PB649 the driver stage is through regulated power supply from PB647. Very complicated. In present condition DC of -2.9 volts are going directly to speaker terminal. No separate protection circuit or speaker crowbar protection.
You have to decide what you want to troubleshoot first. Do you want to know why there is -2.9 volts on the output, or do you want to know why the +-55 power supply isn't starting up? To troubleshoot, you have to pick a symptom you want to focus on investigating, then just work on that and see where it leads you.