High-voltage board dedicated chip to protect the method: Spin Motor,Mini Spin Motor,Washing Machine Spin Motor,Automatic Wash Motor WUJIANG JINLONG ELECTRIC APPLIANCE CO., LTD , https://www.jinlongmotor.com
Chip model protection pin description
TL5001 5 short to ground
TL1451 15 short to ground
TL5451 15 short to ground
BA9741 15 short to ground
BA9743 15 short to ground
MB3775 15 short to ground
AT1741 15 short to ground
AT1380 2 short to ground
KA7500 1 and 16 shorted to ground
TL494 1 and 16 shorted to ground
FA3629 15 and 16 short circuit external capacitor
FA3630 7 and 10 short to ground
OZ960 OZ9622 short circuit to ground
OZ965 4 short to ground
OZ9RR 8 short to ground
BIT31012 and 15 vacuum pins
BIT31025 vacant pin
BIT31054 vacant pin
BIT31064 and 27 vacuum pins
BIT31074 Sinking Pin
BIT319315 vacuum pin
AAT11008 shorted to ground
AAT110715 shorted to ground
Samsung monitor 943NW high voltage board repair tips
Samsung monitor 943NW high voltage board repair tips
Most of the monitors use TMS92903CT, TMS92920CT two high-voltage coils, these two coils have a high damage rate, the common problem, it is the culprit. Use OZ9938 or OZ9939, OZ9938 to protect: 1, when it is completely off, disconnect the 6th foot; when it is off, turn off the 7th foot or connect 3 1N4148 from the third foot to the ground. The OZ9939 chip is connected to a ground from one foot to the ground to protect it. After the protection, the external four lamps are connected, and the two lamps are dark. If you have a high-voltage coil that is broken, take it out, then directly point two lamps, one for each other.
OZ9938 OZ9939 PDF data pin function description 1 drive output 1. The pin outputs a square wave excitation signal that can be externally connected to the gate of the FET.
2 power supply terminal. The voltage of this pin exceeds the undervoltage lockout threshold (4.5V), and the internal circuit of the chip can be started normally.
3 timer setting. This pin sets a timing time through an external RC component for internal shutdown and protection circuitry.
4 brightness control terminal. According to the setting of (11), the foot can input PWM pulse width adjustment signal or DC voltage signal to control the brightness of the lamp.
5 lamp current detection. When the lamp is lit, the voltage of the pin is greater than 0.7V, the integrated circuit enters the normal operation mode, and the pulse width modulation brightness control circuit is started. If the voltage of the foot is zero after the circuit is started, the protection circuit starts to operate and the chip stops the excitation signal output. Therefore, the method of short-circuit current signal cannot be used to judge whether there is an overcurrent fault.
6 feedback voltage detection. This pin accepts the feedback voltage from the high frequency transformer. If the CCFL lamp is damaged or disconnected, the voltage of the pin will increase. The limit voltage is 3.0V, and when this value is reached, the excitation signal is turned off. The user-set voltage value protection circuit with the pin voltage exceeding 7 feet will also be activated.
7 Overcurrent and overvoltage protection value setting. The overvoltage and overcurrent protection action thresholds can be set by an external resistor divider network connected to the pin.
8 empty foot 9 empty foot 10 enable end. When the voltage of the pin is greater than 2V, the internal circuit is started. When the voltage is less than 1V, the internal circuit is turned off.
(11) Dimming mode selection. When the pin is greater than 3V, it is in analog dimming mode, the 4-pin input voltage can be dimmed between 0.5V and 1.25V; when the pin voltage is between 0.5V and 1V, it is in external PWM dimming mode. It is necessary to input a PWM pulse from 4 feet for dimming; when the external resistor is connected to the resistor-resistance timing circuit, the internal PWM pulse is dimmed, and only the DC voltage of the 4-pin input needs to be changed to change the duty ratio of the internal dimming PWM pulse. . When the 4-pin voltage is 0.1V, the duty ratio is 0% and the lamp is the darkest. When the voltage of the 4-pin reaches 1.5V, the duty ratio is 100%, and the lamp is the brightest.
(12) Soft start time setting and loop compensation. The pin is externally connected with a capacitor. At the time of starting, the capacitor is charged. After the charging is completed, the output excitation pulse reaches the maximum value to avoid current impact on components such as CCFL. At the same time, the foot also participates in the loop protection function. When the lamp is open or damaged, the voltage of the pin will rise rapidly. When it reaches 2.5V, the internal bias current charges the 3-pin timer capacitor. When charging to 3V, the chip Turn off the output stimulus signal. Note that this voltage appears only at the moment of the protection circuit action. Since the chip stops after the protection circuit is activated, no voltage is detected on the pin.
(13) Operating frequency peripheral timing resistors and capacitors. The operating frequency can be fixed by setting an external RC component.
(14) Grounding. Analog signal ground.
(15) Drive output 2. The pin outputs a square wave excitation signal that can be externally connected to the gate of the FET.
(16) Grounding. The final stage drive output stage is grounded.
This chip is very similar to the OZ9938. Its 3 feet are time control pins, 5 pins are current detection, 6 pins are voltage detection, and 7 pins are overvoltage protection. Now there are three methods for protection, root circuit design and protection. The reasons are different, can be tested by the following methods: 1. Short-circuit the 3 feet directly to the ground 2. Short-circuit the 6 feet directly to the ground 3. Remove the 7-pin grounding resistance