Observe the machine in use for over a year after the "buzzing" sound. Open the connection regardless of whether DVD or GD Dianyuan power, as long as the power on the amplifier Dianyuan. Main speakers are "buzzing" sound.7smservice manual download site
7smservice manual download site
This "buzzing" sound does not change with the amplifier volume, could hear a speaker within a metre at a distance.7smservice manual download site
7smservice manual download site
Under the "fault" preliminarily concluded that the phenomenon is the amplifier's "failure". Online searching for finding a user's BH-999 power amplifier with the same "failure". Analysis of his "failed" is caused by the amplifier toroidal transformer, method is to use transformer oil treatment immerse the transformer. You can reduce "humming" sound. Was also prepared by this method. But it is too complex and not completely solve the problem. Thus does not have to follow this approach. Check amplifier instructions ready to contact manufacturer. Found manual connection method on third "if all connectors are not firm may produce noise," Lenovo native phenomena but also because lines caused by poor contact? Due to collision when cleaning the back of the line. DVD and amplifier wiring all take off,7smservice manual download site
7smservice manual download site
Only CD player and amplifier line, then power the amplifier Dianyuan, regardless of CD Dianyuan power supply is turned on, speakers in the "buzzing" sound at all. In order to determine which set of lines is poor contact. Repeated cords and removing finalized DVD and amplifier is poor contact of front and rear two sets of wires. First check the wiring and output terminals on the DVD no problem, suspect that the problem is in the power amplifier front and rear input carrier. Open the amplifier. Examination revealed two sets of socket obviously loose. Measurement with multimeter it has poor contact. After changing for good quality with the specifications of socket "failed" excluded.7smservice manual download site