Mobile phone can receive calls, but with normal charger but no response. dYCservice manual download site
 dYCservice manual download site
1, tail damage. Can be measured by tail CN202 17, 18 feet (the right side of two feet) voltage (6 ~ 9 v) to judge the fault parts, if no voltage or low voltage (charger) under the condition of normal, tail plug has a problem. Clean or replace the tail can solve (see figure 1). dYCservice manual download site
 dYCservice manual download site
2, bad start charging circuit. The first 4 feet U105 is high electricity at ordinary times, charging DCIN command signal to the CPU of the N4 interchange, makes the CPU output charging display signals. In the plug in the charger voltage measurement U105 under the charging status of the first 4 feet, the normal value shall be the 3 V or so. If 0 V, can be measured again U105 first 3 feet. (RTC - 3 v3) voltage. If there is no 3.3 V voltage, to show that the fault U104 part; If 3.3 V voltage is normal, the key to check U105, R116, R117 and tail plug (DCVOLT) to 18 feet R116 between copper foil is open circuit, if break can fly line (see figure 2). dYCservice manual download site
 dYCservice manual download site
3 VF open circuit, battery testing end. The end directly communicate with the CPU, if you don't charge fault open will appear, but does not affect the boot. To judge whether the end of the open loop method is as follows. dYCservice manual download site
 dYCservice manual download site
(1) power off condition, good battery. Through the end plug with the charger, if display bright moment, indicated that the side open, unable to communicate with the CPU. dYCservice manual download site
 dYCservice manual download site
(2) boot state, "ding dong" sound can be heard when plug in the charger, but no charging reaction, unplug chargers when there are "ding dong" sound. At this point to check whether VF line and related components between CPU and open (see figure 1). Note: the battery failure also can appear the same fault phenomenon. dYCservice manual download site
 dYCservice manual download site
4, battery voltage detection circuit anomalies. dYCservice manual download site
 dYCservice manual download site
R119, R122 failure also can appear not charging, the CPU will make wrong judgment, think the battery is fully charged and can not be recharged. Judgment method is a model with only one in the cell phone battery of fault, if the indicator is full, then there is something wrong with the battery voltage detection circuit, replace R119, R122 commonly can (see figure 3). But if it is CPU, software problems, also can appear the phenomenon.

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