The Luxman L-480 is a integrated amplifier in the solid state amplifier category. It was manufactured from 1976 to 1980.
- Geoffrey Kolbe (May 6, 2008):
- Solid State Integrated amplifier
- 70 Watts per channel
- Inputs: Phono (MM or MC), Tuner, Aux.
- Outputs: Speakers, 8 ohm, two pairs, either or both
Geoffrey Kolbe (May 6, 2008):There seems to be a problem with a particular transistor pair (2SA 949 and 2SC2229) in the power amplifier section which can lead to an intermittant fault. The transistors run very hot and as they age, one of them can break down intermittantly, (probably Zener breakdown as the rail voltage is quite high at 53 volts), changing the quiescent DC output voltage of the amplifier. The DC voltage should be zero, and a relay disconnects the speakers if the voltage rises to +/- 1 volt or so. The red light on the front panel starts to flash, (as it does at switch on as the voltages settle),
I had this fault in both sides of the PA at different times and I have seen reference to a similar fault elsewhere, so it is probably suffered by other amplifiers. Being an intermittent fault, it is hard to diagnose.
Geoffrey Kolbe (May 6, 2008):Replacing the 2SA 949 and 2SC2229 transistors with a pair of transistors that can take a heat sink would be a good idea.
Geoffrey Kolbe (May 6, 2008):To my ears, an exceptionally clean and honest sound which gives a presence that my other amplifiers do not have. However, there seems to be a design problem in the PA section which can lead to failure in a particular transistor pair.
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