Because of various models of mobile phone attached to different causes, charger socket between each mobile phone charger not common. When the user mobile phone chargers damage or loss, cannot be repaired or buy less charger, cannot use the same key. Universal charger manufacturers see such opportunities, development and production of the mobile phone’s battery charger, the charger because of its small volume, convenient to carry, simple operation, low price, suitable for machine, deeply user’s welcome. Here in shenzhen Alexander tong industrial Co., LTD production of universal tong S538 universal charger for example, this paper introduces the working principle and maintenance method. The charger, in the market share and no random incidental to bring some maintenance diagram of difficulty, according to the work principle of surveying and mapping object, see figure for maintenance.
Universal tong S538 universal charger on exterior design is unique, the panel using transparent plastic production of elliptic clip, transparent plastic panel two fixed distance adjustable stainless steel electrode for charging reed. The rear side panel of one polarity switch switch (test) and the four lights, according to the state of user can adjust the charger electrode distance and the output voltage polarity, and can be easily seen by state indicator of charging battery.
A, principle of work
The charger circuit consists mainly of oscillating circuit, charging circuit, protect circuit, the input voltage AC220V, 50/60Hz, 40mA, output voltage DC4.2 V, output current 150mA in 180mA ~. In charge, first, connect to the rechargeable battery charger panel on whether the test indicator light? If the bright, correct polarity, can switch on the power, Otherwise, the battery charger output voltage polarity and the polarity is opposite, then need to click the polarity switch AN1 (test button). Specific circuit principle as follows.
1 oscillating circuit
This circuit consists mainly of transistor VT2 and switch transformer T1 etc. Switch on the power, communication 220V diode rectifier, VD2 half wave formed around run at 100V dc voltage. The voltage transformer by switching the primary windings 1 T added to transistor VT2 c extremely, meanwhile, the voltage by starting resistance is the R4 VT2 is provided a b bias voltage, make VT2 conduction. At this time, the transistor VT2 is composed of T1 and switch transformer intermittent oscillating circuit start working, switch transformer T 1-1 in current through the primary windings. Because of the positive feedback effect, in transformer windings of the 2-1 the voltage induced by the feedback resistance and capacitance R1 added C1, make the b VT2 transistor VT2 b very current flow, quick in saturated zone. With the capacitance C1 ends, voltage VT1 b voltage gradually lowered, make triode VT2 is gradually saturated zone, its from beginning to reduce collector current transformer T, 1-1 in the primary windings of flux also began to decrease. In transformer windings of the 2-1, the negative feedback voltage induction deadline, completing a rapid VT2 oscillation periods. During the globe in VT2 into the transformer windings is 1-3 induced a 5.5 V ac voltage, or as the recharging voltage level.
2 charging circuit
This circuit consists mainly of a RuanSu seal block IC1 (YLT539) and the transistor VT3 etc. From the 1-3 transformer windings induction of ac voltage 5.5 V VD3 diode rectifier, filter, output capacitance C3 a dc voltage (about 850 V), the voltage no-load part to VT3 triode e extremely, Another part of RuanSu to block sealing IC1 YLT539 (1), provide the job power. Integrated block IC1 job power after the start work, in its eight feet output low level, VT3 triode charging pulse conduction, dc voltage began to 8.5 V battery charging E.
As for the rechargeable battery E, 4.2 V lower voltage is the voltage resistance by sampling R11 R12 pressure, and add to the integration of six feet IC1 block, the lower voltage reference voltage IC1 integrated blocks the internal integrated blocks, 8 feet IC1 output level is lower, the transistor VT3 b extremely potential also lower the flux, the guide, dc voltage (8.5 V) by switching to cell polarity S1 fast charging E. Because of the integrated block IC1 2, 3, 4 feet and capacitance C4 common component oscillating circuit, the two feet of the output pulse vibration resistance to battery indicator R16 LED1 (green), the positive anode block received eight feet IC1. The battery just answer one circuit IC1, integrated block 8 feet output level is lower, the battery indicator light LED1 flashing. With rechargeable battery charging prolonged, the voltage, integrated block slowly IC1 eight feet slowly rising, charging output voltage LED1 lights flashing light become weak gradually.
When the battery E slowly when filling to 4.2 V, integrated block 6 feet IC1 also reached its internal potential reference voltage 1.8 V. At this time, the integrated circuit IC1 piece inside, make its eight feet moves voltage output level, VT3 triode, rechargeable lights no deadline LED1 flashing lights, and extinguished by LED2 (green) destroyed brighten.
3 voltage protection circuit
This circuit consists mainly of transistor VT1, diode VDZ1 etc.
Over-voltage protection: when the output voltage rises, in the 2-1 transformer windings of the inductive voltage feedback, capacitance increases by charging pressure. C2 When the capacitor voltage exceed voltage at C2 VDZ1 diode, the voltage stabilizing conduction, VDZ1 diode breakdown voltage, the base of transistor VT2 is low, make its conduction time shorten or quickly, the switch by coupling, transformer T1 secondary output voltage. Conversely, the output voltage, thus ensuring stable output voltage.
Over-current protection in the switch on the power, or when certain causes a moment when the current transistor VT2 in R5, R6, the pressure drop is big, make the over-current protection tube, VT1 conduction deadline, thus effectively prevent VT2 VT1 switch for current impulse and damage. Also on the resistance of the pressure drop, R6 make voltage capacitance C2 ends, over-current protection principle, process and the same voltage here not repeated. VT1 triode tube is over-current protection, R6 is VT2 R5, over-current protection of sampling.
Second, the common breakdown maintenance
Ex.1: connected with rechargeable batteries and power supply, power LED3 indicator lights and TEST pwi LED4 TEST bright, and LED1 charging and LED2 not bright lights, no voltage output, cannot give the battery.
Analysis: the fault is access oscillating circuit switch without work charger. In the actual repair process, found switch pipe resistance and VT2 is most damage R6. Normally, battery recharging circuit E working voltage, low probability of its component damage is not great, namely after subprime T1 transformer switch is the probability of damaged circuits.
Example 2: connected with rechargeable batteries and power supply, each state indicator shows normal, but is not charged rechargeable electric or longer.
Analysis: the fault is overhaul VT3 triode 8550 (with normal tube), after the change, can remove the faults. If VT3 triode, reoccupy table test capacitance C3 (100 mu F / 16V) ends in dc voltage, normal 8.5 V. If the voltage is normal, should check R7 resistance, integrated blocks or IC1 IC1 integrated blocks the normal parameters such as schedule. If the voltage, measure voltage transformer switch T1 subprime, normal in exchange 5.5 V. If the voltage is normal, capacitance C3 or rectifier diode VD3 damage, If the voltage transformer, should check switch before each element and its magnitude T1.