9V rechargeable battery

　　Advanced switching 9V rechargeable battery uses dummy load to repair the circuit

　　The switching 9V rechargeable battery controls the turn-on and turn-off time of the switch tube in the circuit, and it can continuously stabilize the output voltage in the circuit. It is a relatively mature technology that has been developed in recent years. A false load refers to a component that can receive electrical power in a certain circuit or the output port of a circuit. It is called a false load. The false load also has the ability to detect circuit errors in the switching 9V rechargeable battery. So how to use the false load to check? Next we focus on this issue.

　　When the load of the switching 9V rechargeable battery is short-circuited, the output voltage will decrease. Similarly, when the load is open-circuited or no-load, the output voltage will increase. During maintenance, the dummy load replacement method is generally used to distinguish whether the 9V rechargeable battery part is faulty or the load circuit is faulty. Regarding the selection of dummy load, generally a 40W or 60W light bulb is selected as the dummy load. The advantage is that it is intuitive and convenient. Based on whether the light bulb emits light and the brightness of the light, it can be known whether the 9V rechargeable battery has a voltage output and the level of the output voltage.

　　Compared with the advantages, the disadvantages are also very obvious, mainly reflected in the problem of resistance. For example, the hot resistance of a 60W light bulb is 500Ω, while the cold resistance is only about 50Ω. Assume that the main voltage output of the 9V rechargeable battery is 100V. When a 60W light bulb is used as a dummy load, the current when the 9V rechargeable battery is working is 200mA, but the main load current at startup reaches 2A, which is 10 times the normal operating current. Therefore, a light bulb is used as a dummy load. , it is easy to make it difficult to start the 9V rechargeable battery, because the greater the power of the bulb, the smaller the cold resistance, therefore, the starting current of the high-power bulb is larger, and the 9V rechargeable battery is more difficult to start.

　　When calculating the starting current and operating current of the 9V rechargeable battery, you can use the formula I=U/R to calculate: the load current when the 9V rechargeable battery is starting is 100V/50Ω=2A, and the load current when the 9V rechargeable battery is working is 100V/500Ω=0.2A. However, it needs to be noted. Note: The above is a theoretical calculation, and the actual calculation may be different. In order to reduce the starting current, you can use a 50W soldering iron as a dummy load (both hot and cold resistance values are 900Ω) or a 50W/300Ω resistor, which is more accurate than using a 60W light bulb.

　　Some power supplies can be directly connected to dummy loads, but some power supplies cannot. Specific problems need to be analyzed in detail. The following is a detailed explanation of the three types of situations.

　　The first type is a switching 9V rechargeable battery with row pulse synchronization, which can disconnect the row load and directly connect the dummy load. This kind of switching 9V rechargeable battery is purely a self-excited switching 9V rechargeable battery. The purpose of introducing forward row and reverse pulses at the base of the switching tube is to synchronize the self-excited oscillation of the switching tube with the horizontal pulse, so that the pulse radiation of the switching 9V rechargeable battery interferes with the oblique bars of the screen. Limited to the line scan inverse path, so no interference is visible on the screen. The horizontal pulse applied to the base of the switching tube only causes the switching tube to turn on in advance during the cut-off period, and basically does not constitute an auxiliary excitation function. Therefore, it is called a switching 9V rechargeable battery with horizontal pulse synchronization. The way to judge whether it belongs to this kind of 9V rechargeable battery is that when the reverse pulse is turned off, the switching 9V rechargeable battery only makes a sound (because the oscillation frequency becomes lower), and the output voltage does not drop. Therefore, this 9V rechargeable battery can disconnect the row scanning circuit and use the false load method to repair it.

　　The second type is a separately excited switching 9V rechargeable battery. For separately excited power supplies without row pulse synchronization, the row load can be disconnected and directly connected to the dummy load. For a separately excited switching 9V rechargeable battery with line pulse frequency locking and indirect sampling, when it is directly connected to a false load (especially when connected to a larger power bulb such as 150W), the output voltage may drop significantly or there may be no output, because this type of 9V rechargeable battery, although The addition of row pulses only plays a role in synchronization and frequency locking, but does not participate in oscillation. However, the row synchronization pulse can advance the conduction time of the switch. At this time, the 9V rechargeable battery has the strongest load capacity. If the row load is disconnected, the row load will The synchronization pulse loses its function, the 9V rechargeable battery's ability to carry a load is bound to be reduced, and the sensitivity of the 9V rechargeable battery voltage stabilization coupled with indirect sampling is low, and the output voltage is bound to be reduced. However, if the voltage stabilizing circuit of this type of 9V rechargeable battery adopts direct sampling (the sampling voltage is taken from the secondary side of the switching transformer), due to the high voltage stabilization sensitivity, it can be disconnected from the line load and directly connected to a false load or even no-load for maintenance.

　　The third category is the switching 9V rechargeable battery with line pulse auxiliary excitation. The reverse pulse of this kind of switching 9V rechargeable battery not only completes the synchronization of the self-oscillation frequency of the switching 9V rechargeable battery, but also forms an indispensable part of the switching tube feedback network. The working process of this kind of switching 9V rechargeable battery is: after the power is turned on, the switching tube generates self-excited oscillation. Under the rated load, its feedback network can only make the output terminal generate a voltage lower than 40% of the normal output. This voltage starts the row scan, and the row pulse The feedback provides auxiliary excitation to the switch tube to achieve the rated voltage output.

　　This has two purposes: First, it has a voltage reduction protection function. Once the row scanning circuit fails, whether it is open circuit or short circuit, the output voltage of the switching 9V rechargeable battery will drop to 60% of the original value, reducing the scope of damage. Second, both the 9V rechargeable battery and line scan have a very short soft-start process, which reduces the failure rate of the 9V rechargeable battery and line scan. For this type of 9V rechargeable battery, if the feedback row pulse circuit is removed, the output voltage of the 9V rechargeable battery will drop by 40% to 60%, or even the output voltage will be very low. Obviously, this kind of 9V rechargeable battery cannot be directly disconnected and the line scan is inspected using the false load method, because even if the power circuit is normal at this time, it is impossible to output the rated voltage. The way to distinguish between 9V rechargeable battery and row scanning circuit faults is to use an external 9V rechargeable battery to power the row scanning circuit separately. If the row scanning circuit works normally, it means that the switching 9V rechargeable battery is defective.

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