Reply to thread

Message: <blockquote data-quote="laal" data-source="post: 10454582" data-attributes="member: 94459">How to repair keypad problem in china phoneFirst  we need to know china phone keypad  connected with PCB how way-  (A) Direct on  PCB  (B) Flex System (flex cable  direct  soldering pcb to keypad panel)  (C)  Flex and socket system include  (flex one side soldering with key panel  other side connect to pcb with  socket)  (D)  only Socket System (here have 2  socket, 1 with key panel others with  pcb)      Keypad  problem have various type-  1. All key not work.  2. some key work and some other not  work.  3. sometimes work and sometimes not   work.     1. All key  not work china phone all key not work  for this type of  problem-  (A) though its touch  screen phone, first try to  disconnect touch panel line from phone pcb  or display flex (4 line)  (B) though not solve and keypad direct   on pcb first you try to good clean full pcb with cleaner.   (C) though not solve now you try to   format/flash your phone because some time key problem come from software   problem.  (D) though still not  solve now you   check must be CPU. 95% china phone keypad directly going  in cpu. and   other 5% first going to resistor or capacitor near the cpu  or keypad   than going to cpu. so now first check them than you can try to  re-hot,   re-soldering or changing cpu. (E) though its flex or socket system, first check GND    connection continuslay pcb to key panel. next check full flex or socket    all line going continuously pcb to key panel or not. also sometimes   flex  or socket shorted with other line or gnd so check also them.  (F) Also you can check all key anyone  is  short 2 line.  (G) sometimes  keypad line broken from  cpu pin on pcb to key panel, so check them.     2. Some key work and some  other not work- Some key work and some  other is not work for this  type of problem-  (A) maximum time this problem we face   for flex or  socket system keypad. so check flex cable and socket all   line any line  is broken or not and though need change them. and check   all key  connection on key panel.  (B)  though its direact on pcb, some of   key line broken internaly. and  maximum china phone have alternative   test point near every key or with  other key on keypad. so check them   with multimeter and though need  connect  to not work key with near   testpoint or other working key.  (C) common problem is keypad metal ball    (which is short 2 line on key when we press) sometimes its damage for    phone water damage or over key voltage, so clean them or change.  (D) also try to check line continuously   from cpu to not working key.   3. sometimes work and sometimes not work- this problem come from this defect-  (A) flex or socket system keypad any  line is  bad soldering or do lose contact. check them andre-soldering or keep there line join with extra ware.  (B) for cpu bad soldering or cpu pin is   broken. so re-hot or re-ball cpu.</blockquote>

Verification: Hathara warak wissa keeyada? (Hathara wadi karanna 20)

Top Bottom