Analysis and maintenance of: according to the analysis of the fault phenomenon. As a result, there are three reasons for the failure of: from electronic keyboard synthesizer to mixer signal input circuit fault; the second is the electronic keyboard synthesizer circuit fault; the third is with headphones listening tuning and electronic keyboard synthesizer signal input channel without sound, the increase of the gain, peak indicator light is not bright that mixer on the channel circuit failure.nY4service manual download site
Check the electronic keyboard synthesizer output to the console input signal lines and the connector are all normal. Will console electronic keyboard synthesizer signal line pulled out, in tune and other signal channel pilot, the normal speakers sound output, just sound signal amplitude is higher, adjusted gain output is normal. The fault is judged on the circuit of the electronic keyboard synthesizer signal input on the mixer..nY4service manual download site
Repair, unplug the mixer power plug, open the console of the machine cover, check the tuning and electronic keyboard synthesizer signal input processing circuit and access the channel mouth no problem, gain measurement and push and pull the resistance value of the potentiometer are normal, normal test signal input switching switch, channel cable to connect is also normal.nY4service manual download site
Plug in the power supply, switch on the mixer, measure the input of the signal input gain of the integrated block, found the integrated block of the foot +Vcc working voltage drop. A 10 - current limiting protection resistor is found on the circuit board along the circuit board, and the resistor is V +12 at one end, and no voltage is received from the other end of the integrated block. Will be removed with the resistance, with the use of resistance file meter, the resistance was the same as the same resistance, the starting trial, the electric resistance, the failure is still. After the shutdown, the same type of integrated block, re test machine, troubleshooting.

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