Panasonic KX-TG7841S Service Manual

Also see for KX-TGA20B: Service manual

Contents

Panasonic KX-TG7841S Service Manual Manual pdf 24 page image

24KX-TG7841/KX-TG7842/KX-TG7843/KX-TG7844/KX-TG7845/KX-TG365SK/KX-TG7871/KX-TG7872/KX-TG7873/KX-TG7874/KX-TG7875/KX-TG385SK/KX-TGA6804.9.3. Charge CircuitCircuit Operation:When charging the handset on the Base Unit, the charge current is as follows;DCP(5.5V) → F301 → R371 → R372 → D362 → CHARGE+(Base) → CHARGE+(Handset) → R8 → Q3 → F1 → BATTERY+...Battery...BATTERY- → R45 → GND → CHARGE-(Handset)→ CHARGE-(Base) → GND → DC-(GND)In this way, the BBIC on Handset detects the fact that the battery is charged.The charge current is controlled by switching Q9 of Handset.Refer to Fig.101 in Power Supply Circuit/Reset Circuit (P.15).4.9.4. Battery Low/Power Down DetectorCircuit Operation:“Battery Low” and “Power Down” are detected by BBIC which check the voltage from battery.The detected voltage is as follows;• Battery LowBattery voltage: V(Batt) 2.35 V ± 50 mVThe BBIC detects this level and " " starts flashing.• Power DownBattery voltage: V(Batt) 2.1 V ± 50 mVThe BBIC detects this level and power down.4.9.5. SpeakerphoneThe hands-free loudspeaker at SP+ and SP- is used to generate the ring alarm.CHG +Q4R45R4 47KR610KQ9GNDR7 CHG DET (34)CHG CTRL (32)100KCHG -GNDBATT +BATTERY2CELLBATT -GNDBBICIC1Q2R8Q3C27R2R9