1, the working principle
The charger circuit mainly by the oscillation circuit, charging circuit, voltage regulator protection circuit etc., Dell Inspiron 2500 Battery, the input voltage of AC220V, 50/60Hz, 40mA, the output voltage DC4.2V, output current 150mA ~ 180mA. In the charge before to be connected to rechargeable batteries, charger panel test to see whether the bright lights? If bright, that polarity is correct, can be connected to the power charge; otherwise, indicating the polarity of the battery and the charger output voltage polarity is the opposite, and then need to click polarity switch AN1 (test button) Caixing.Dell Inspiron 2500 Battery, Dell Latitude CPX Battery, Dell Latitude C600 Battery, Dell Latitude C610 Battery, The specific circuit principle is as follows.
1. Oscillator
The circuit mainly by the transistor VT2 and switching transformer T1 so on. After power on, AC 220V half-wave rectified by the diode VD2 to form a DC voltage of about 100V. The voltage by switching the primary winding of transformer T, 1-1, added a c-polar transistor VT2, while the voltage through the startup resistor R4 for VT2 of the b pole to provide a forward bias voltage, so that VT2 conduction. At this point, transistor VT2 and switch transformer T1 consisting of intermittent oscillator circuit to work, the switch transformer T, 1-1 in a current through the primary winding. As the positive feedback role in the transformer winding T 1-2 of the voltage sensor through the feedback resistor R1 and capacitor C1 added to the VT2's b pole, so that the b transistor VT2 conduction current to increase very quickly into the saturated zone. As the voltage across capacitor C1 rising, VT1 of the b voltage gradually reduced, so that transistor VT2 gradually withdrawing from the saturation region, its collector current began to decline in the primary winding of transformer T, 1-1 arising from magnetic flux also started to decrease. T, 1-2 in the transformer winding voltage sensing negative feedback, so that the rapid VT2 deadline to complete an oscillation cycle. In the VT2 into the cut-off period, the transformer T, 1-3 windings on the sensor out of an AC voltage of about 5.5V, as the post-charge voltage level.
2. Charging circuit
The circuit mainly by a soft-plastic Manifold IC1 (YLT539) and the transistor VT3 so on. T, 1-3 from the transformer windings of the AC voltage 5.5V induced by VD3 rectifier diode capacitor C3 filter, the output of a DC voltage of about 8.5V (no load), the voltage is part of the added transistors VT3's e pole ; sent to another part of the soft plastic Manifold IC1 (YLT539) of a foot, to provide working power source. Manifold work of IC1 have started work after the power is in its 8-pin output low charge pulses, so that transistor VT3 conduction, DC 8.5V voltage E began to charge the battery.
When the rechargeable batteries E to be lower than 4.2V voltage, the voltage through the sampling resistor R11, R12 partial pressure, the added Manifold IC1's 6 feet, the voltage is lower than the internal reference voltage Manifold IC1 more integrated block IC1's 8-pin output level of the lower transistor VT3's b great potential the lower the flux of its lead larger DC voltage (8.5V) by the polarity switch S1 to the battery E fast charging. Because of 2,3,4 Manifold IC1 pin and a capacitor C4 together constitute the oscillator resonant circuit, the two pin oscillator output pulses sent through the resistor R16 charging indicator LED1 (green) is positive, its negative Manifold IC1 receives the 8 feet. Just access the circuit in the battery, the Manifold IC1 8-pin output level, the lower the charging indicator light flashes LED1 strong. With the extended charge time, battery charge voltage by slowly rise,Dell Inspiron 2500 Battery, Dell Latitude CPX Battery, Dell Latitude C600 Battery, Dell Latitude C610 Battery, Manifold IC1 8-pin output voltage slowly rise, flashing LED charge indicator LED1 gradually weakening.
E slowly when the battery charge to about 4.2V when the 6-foot Manifold IC1 potential reached its internal reference voltage of 1.8V. At this point, the internal circuitry Manifold IC1 moves to 8-pin voltage output high level, transistor VT3 end, the charge indicator LED1 is no longer flashing light and go out, full of light LED2 (green) light from the eradication of change.
3. Regulator protection circuit
The circuit mainly by the transistor VT1, Dell Latitude C600 Battery, voltage regulator diode VDZ1 so on.
Over-voltage protection: When the output voltage increases, the transformer T, 1-2 voltage feedback sensing winding terminal will be increased, then the capacitor C2 of the charge pressure is increased. When the voltage across capacitor C2 exceeds the value of regulator diode VDZ1 the regulator, the regulator diode VDZ1 breakdown conduction, the base voltage of transistor VT2 down to on-time or quick cut-off, after switching transformer T1 coupled will bring the secondary output voltage reduction. On the contrary, the output voltage is increased, thereby ensuring that the output voltage stability.
Over-current protection: In the moment or when connected to the power transistor VT2 for some reason so that when the current is too large, the R5, R6 on the voltage drop on the big, so that over-current protection tube VT1 conduction, VT2 end, so as to effectively prevent the switch Pipe VT1 too large due to the impact of current damage. At the same time the voltage drop across resistor R6, so that voltage across capacitor C2 increases, since over-current protection process and the regulator on the same principle, not repeated here. Transistor VT1 is the over-current protection tube, R5, R6 is a VT2 protection over-current sampling resistor.
2, common troubleshooting
Example 1: To be connected to rechargeable batteries and power supply, the power PW and testing of indicator light LED3 light TEST LED4, while the charge LED1 and LED2 is full of light does not shine, no voltage output, not charging the battery.
Analysis of maintenance: This charger failures are mostly due to switch oscillation circuit did not work. The actual repair process, found in VT2 switch and resistor R6 damage to a maximum of. Under normal circumstances, the battery charging circuit voltage E, the lower the probability of damage to its components is not large, that is, Dell Latitude C610 Battery, switch the circuit after the transformer T1 secondary damage to the probability of not very great.
Example 2: to be connected to rechargeable batteries and power supplies, the various status indicators show normal, but they can not be recharged into electricity or charge a long time.
Analysis of maintenance: this failure are mostly Transistor VT3 (8550) damage,Dell Inspiron 2500 Battery, Dell Latitude CPX Battery, Dell Latitude C600 Battery, Dell Latitude C610 Battery, with normal tubes replaced, you can troubleshoot. If the transistor VT3 normal, then the table measuring capacitor C3 (100μF/16V) at both ends voltage of about 8.5V to normal in DC. If the voltage is normal, should check the resistance of R7 or Manifold IC1, Manifold IC1 normal parameters such as the pin shown in the table. If the voltage is low, and then measuring the output voltage switching transformer T1 secondary, normal in the exchange of around 5.5V. If the voltage is normal, indicating capacitor C3 or the rectifier diode VD3 damage; if the voltage is low, should check the switch transformer T1 and its former level of each component.
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