In this paper, the Yamaha EMX2300 amp repair instance, and circuit analysis for common understanding, to explore. Yamaha's EMX2300 is a high-fidelity OTL power amplifier, first stage differential amplifier input, ultimate complementary high power output, between before and after direct coupling. This circuit has stable work, and frequency response, low distortion and so on, and in recent years specialized and household power amplifier circuit is widely used.HdFservice manual download site
However, as a result of multiple direct coupling, once one of component deterioration or damage, can cause an entire circuit of changes, ranging from lead voice or distortion, while causing extensive damage of components, even burning your speaker system. One voltage change, it will cause the multi-point voltage change, which create difficulties for a fault estimation and maintenance. I also found in the long-term maintenance after the access when this type of amplifier, and if the troubleshooting does not completely power on test machine often gives rise to new devices when damaged again, resulting in economic losses. Therefore, maintenance practices require some safety inspection, in order to enhance efficiency and reduce the deadweight loss.HdFservice manual download site
HdFservice manual download site
Maintenance example 1: a colleague trying to fix a Yamaha EMX2300 amplifier and mixer combination machine, use the pointer multimeter measured 8 on the amplifier Board and 4 push tube power amplifier all burned out, two speaker internal speaker are all burned. He prepared the pieces directly after the full replacement of damaged parts according to specifications, in the case of no level the mixer before you connect, connected to the power supply would like to give it a try yet, but after only one minute after power, whatever emerge within the white smoke. Power outages after the inspection, instead of the power tubes are damaged, losses will not be small. Later sent to our repair Department, I have a warning, and after careful consideration, known damage to components, connected to our homemade special power supply for low-voltage maintenance, in the case of elements not thoroughly checked out the power on there will be no problem, finally found some resistance growing, eventually resolved the problems.

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