Luxman M-300 Repair And Restoration
This Luxman M-300 power amplifier is in good cosmetic shape
You can run this Luxman M-300 power amplifier in class AB or class A with a turn of a switch.
This Luxman M-300 power amplifier came with a nice wood case.
There are several screws that hold the wood case to the chassis. Once removed the chassis will pull out from the front.
The first thing that I notice with the chassis out of the case is that the positive speaker terminal for the left channel is broken off.
There is plenty of wire so I should be able to replace the speaker terminal without to much trouble.
The replacement speaker terminal is not an exact replacement but it's better then none at all. You can only tell the difference at the back of the M-300.
With this Luxman M-300 power amplifier out of it's wood case I can get a good look at it's layout.
This Luxman M-300 has a very large heatsink area. Any amplifiers that run in class A usually do.
There is some dirt and dust that needs to be cleaned up. Almost all vintage audio repair or restorations involve plenty of cleaning.
With the bottom cover removed on this Luxman M-300 you can see the output transistors and driver boards.
I am able to clean the pots and switches with dexoit without removing the faceplate. I use a piece of paper towel in the chassis to catch any overspray or dripping.
A small portable LED light can help you to see in those dark areas.
I now have a CD player plugged directly into this Luxman M-300. I'll give a listen on the test bench and see if everything sounds okay.
Both class AB and class A sound fine. 40 watts per channel in class A mode, 150 watts per channel in class AB mode.
In class A mode this Luxman M-300 run's very very warm(hot). Never block the top ventilation opening at the top of the power amplifier.
You must follow the service manual for the Luxman M-300 to set the idle current for both the class A and class AB modes.
There are two pots that you adjust for the two different idle currents on the Luxman M-300.
Any vintage audio repair or restoration should include bench testing with test equipment that is made to measure power, distortion, etc.
Both channels tracked very close to each other. This will allow both the left and right channels to sound balanced when listening to music.
The distortion numbers were very good on both channels throughout the various frequencies that were tested.
This Luxman M-300 power amplifier tested well on the test bench. It's about time to put the wood case on and listen to some music.
This Luxman M-300 power amplifier repair and restoration in complete. It's time for some music!