, just finished repairing the output stage of an LV-103 that has been sitting round for the last 10 years.
Used 2SK1529 and 2SJ200 as described here:
http://www.diyaudio.com/forums/solid-state/201646-luxman-lv103u-replacing-output-fets.html
In lack of a better value for the new transistors, I set idle current at 200mA as stated in the manual for the original output devices. Current changed a bit during heating, so I made a rough adjustment and fine-tuned after 30 minutes (again as per manual).
So to my question: Close to the PA transistors there is a small PCB that according to the manual is "current limiter circuit". I don’t seem to be able to insert picture, but I have determined that transistors Q7372 and/or Q7374 are dead.
How critical is this circuit in terms of amplifier protection and sound quality?
I did not have any replacement transistors at hand. The amplifier did not come back alive after repair of the PA stage, and the speaker relay would not be activated until I cut all wires to the right channel protecting circuit. Been listening to the amp for the last few hours on some test speakers and like what I hear so far. Haven’t dared put it on my good speakers yet.
Should I repair the current limiter board or simply leave it disconnected
Used 2SK1529 and 2SJ200 as described here:
http://www.diyaudio.com/forums/solid-state/201646-luxman-lv103u-replacing-output-fets.html
In lack of a better value for the new transistors, I set idle current at 200mA as stated in the manual for the original output devices. Current changed a bit during heating, so I made a rough adjustment and fine-tuned after 30 minutes (again as per manual).
So to my question: Close to the PA transistors there is a small PCB that according to the manual is "current limiter circuit". I don’t seem to be able to insert picture, but I have determined that transistors Q7372 and/or Q7374 are dead.
How critical is this circuit in terms of amplifier protection and sound quality?
I did not have any replacement transistors at hand. The amplifier did not come back alive after repair of the PA stage, and the speaker relay would not be activated until I cut all wires to the right channel protecting circuit. Been listening to the amp for the last few hours on some test speakers and like what I hear so far. Haven’t dared put it on my good speakers yet.
Should I repair the current limiter board or simply leave it disconnected