Bose 1800 service manual
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Extracted text from bose 1800 service manual (Ocr-read)
Page 1
The BOSE 1800 amplifiers have individual power supplies for each channel. They combine an excellent solidity and reliability with an excellent performance and protection. DESCRIPTION The BOSE 1800 amplifier is designed with two low noise high speed op-amps per channel, followed by a heat sink mounted bias circuit, to provide precise temperature compensation; and a full complementary output stage, featuring ten 200 watt transistors in each channel (2000 watt total dissipation capa- bility per channel). The power and drive-transistors are mounted on two heatsinks with "SIL-PADS" tor superior long life heat transmission. The "SIL-PAD" is a new product, specially developed tor this purpose and gives a better heat transmission and has a much langer life than the conventional method with mica-isolators and silicon paste. Experience has proved, that af ter some time, by drying of silicone paste, the heat transmission reduces strongly and power devices are "blown" without even delivering maximum power. The "SIL-PAD" prevents such a breakdown. A 2-speed temperature operated urtra low noise fan is build in for optimal cooling. With specially designed alruminium profiles, the BaSE 1800 amplifier is very solid and really capable of handling heavy raad conditions. FRONT PANEL The BOSE 1800 amplifier is provided with a led-indication, showing the cause of trouble or misuse in various situations. Besides the usual clip-indication, each channel has a led for: a) heavy overlaad/speaker short-circuit, b) overheating. In case, a or b, the leds illuminate, this also means that the specific protection is working and the amplifier delivers no power into the laad until the situation is within acceptable limits again. The BOSE 1800 amplifier also protects your (expensive) loudspeakersystem against switching peaks or D.C. current. Approximately 3-5 seconds af ter switchingon the mains power, the laad is coupled to the amplifier. When switching off mains, in case of mai.ns-failure or D.C. at the output, the load is decoupled very quickly.
Page 2
RE AR PANEL On the rear panel you will find two inputs per channel. a) One three pin XLR for balanced and unbalanced mode. b) One phone jack, only for unbalanced mode. When using the phone jack, pin two of the XLR will automatically be connected to ground. If desired, signal ground can be separated from chassis ground, by switching ground lift.