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Trouble shooting of the mouse repellent device

News by ninechip | On 2018-07-21 08:43

1. the noise of the cat became ugly, and then the machine started without any barking.

The fault location should be in the cat integrated circuit or the audio power amplifier circuit, but the open shell inspection is FU fuses. The power supply circuit was found to be short circuited by VD1, replaced and replaced by a power supply, and the power supply was restored to normal 6V, but the sound of the cat was still ugly. Try replacing speakers, C9, IC3, C6, VT1 and so on are invalid; using other music chip test also cannot do, then think maybe power is not good. Using digital multi-meter, the positive reading number of 4 diodes is about 0.65, and the reverse reading is infinite. Normal (otherwise, if there is a short circuit, it will cause the burning insurance; if a circuit breaker will form a half wave rectifying, the rectifier voltage and ripple will be affected). Next, the C1 found that one of the pins was loose in solder joints, and the trouble was removed after repair.

The analysis is that the C1 off welding not only increases the ripple and the sound quality is bad, but also causes the VD1 to be impacted by the current when the machine is on the machine. When the quality of the VD1 is not good, it may break through the short circuit damage and cause the fault.

2. when it is connected to the power supply, it can make a normal cat call, but then it cannot continue to call.

This phenomenon indicates that the power supply, music block and power amplifier circuit are basically normal, and the fault location may be in the time base circuit. The time base circuit of the circuit is connected to an unstable multi-vibrator. When the output voltage is normal, the foot potential changes with the charge and discharge of C2. But at this time a cat call after a call to test IC1 (2), the foot is always high level; discharge end of the foot is also a high level, no signs of discharge, suspected IC1 bad, but the replacement after the failure is still. To find out the peripheral components, it is found that the BP2 VD2 end is not connected with the other ends, causing the C2 discharge circuit to break, the time base circuit is no longer turned, and cannot continue to trigger the IC2 to make a cat call. Troubleshooting after replacing RP2.

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