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KEYBOARD BLOCK check
Check U302 MCU pin 43,42,41,40,39 at High state(5V)? without press any key
OK
Press power key and check U302 pin 43 = low (0V) ?
OK
Check U302 pin 38 (LED green) will have transition from hi to low or low to hi when we press the power key??
NG, MCU no response
Check U302 pin 20= 20MHz ? and pin 44 (VDD)=5V ? and pin 10 (reset)=0V ? at normal condition
NG
NG
OK
NG
Mechanical was stuck, Check !
Replace
If still no Led green indicator, check Q102, R106 & LED at keyboard !! cold solder or bad
If one of this item was NG, check the relative circuit
OK
Without press key and change mode, Check U302 pin 16,17(sda,scl)= hi 5V ? or keep transition ?
OK, no keep transition
Replace U302 MCU
Keep transition, that means eeprom no response
NG
Check U300 eeprom 24LC04 relative circuit, check U300 pin 7 = low?
NG |
| OK |
|
|
|
Check JP202 is |
| Check U300 pin 8 |
connect ? |
| (vdd)= 5V, and check |
|
| R300,R301 cold solder |
|
Replace eeprom
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