Temperature impact test box circuit repair method, circuit diagram analysis. The current detection circuit is mainly used to detect the temperature impact test box compressor operating current, for the temperature impact test box compressor in the work of current is too large or too small, in order to protect the compressor and set the protection circuit. In the circuit, D4 is a rectifier diode, D7 is a clamp diode, and the main chip pin input level is clamped to 5.7V, and C9 is a filter capacitor.
Oh, how it works. When the temperature impact test chamber compressor is working, the corresponding voltage is induced across the induction coils A and B. After D4 rectification and C9 filtering, the signal is input to the main chip (26) pin via the R10 to monitor the change of the compressor current. When the operating current of the compressor increases, the induced voltages of terminals A and B increase correspondingly, and the voltage of the input main chip (26) after rectifier filtering increases. When the input voltage of the chip (26) is too high, the chip can determine that the operating current of the compressor circuit is too large at this time, thereby cutting off the power supply of the compressor and protecting the compressor. In general, the current detection circuit is protected when the operating temperature of the temperature impact test box reaches 13A or more.
☉, temperature impact test box current detection circuit failure analysis; induction coil on the induced voltage is wrong, D7 breakdown short circuit, resulting in the main chip (26) pin potential increased, prone to misjudgment of current, resulting in shutdown.
The D4 and C9 filter elements break down during operation and the current detection board loses its protection function.
Temperature impact test box current detection circuit drive circuit
☉ In the electronic control of the temperature impact test box, the main chip processes various input signals and controls other circuits to drive the load to complete the predetermined function of the air conditioning. The driver circuit is to amplify the power of the main chip output signal, control the load of the general drive circuit including IC2 (2003) power amplifiers, relays and related components of the final stage of the promotion circuit.
☉, temperature impact test chamber current detection circuit compressor drive principle. The main chip (36) pin outputs the start control signal, which is sent to pin 7 of IC2 (2003). The internal circuit amplifies the current of the drive signal sent from the main chip, so that one end of the RL3 connected to +12V forms a loop to ground, and the relay coil Power on and pull, 220V AC power supply to the compressor.
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