DDD P845LML maintenance log 
Plate image is as follows:
Client could run this board does not boot, the value of visual play no problem, plug the trigger flash cards measuring Jimie, according to the phenomenon of judging either has short circuit CPU power, or CMOS-hop-hop anti-cap
The difference between the words is the short circuit CPU power will generally trigger a flash of “squeak” is heard. And this board there is no such sound, initially to determine that a fault lies in the CMOS. First test
CMOS voltage jump cap to see whether the anti-jump, there is no anti-jump, but found that the low-voltage power supply 【because I was stuck in the】. Plug in the power normally should be 3.3V
The difference between the words is the short circuit CPU power will generally trigger a flash of “squeak” is heard. And this board there is no such sound, initially to determine that a fault lies in the CMOS. First test
CMOS voltage jump cap to see whether the anti-jump, there is no anti-jump, but found that the low-voltage power supply 【because I was stuck in the】. Plug in the power normally should be 3.3V
Short Diode test 3.3V input and normal
CMOS circuits due to problems, the circuit of the capacitance of the probability of serious damage, so the CMOS circuit directly to the capacitor.
CMOS circuits that a picture is as follows:
CMOS circuits that a picture is as follows:
On-board drawn into the circuit diagram:
Circuit is as follows:
Removed capacitance, the measured voltage CMOS-hop hat normal.
Boot does not flash on the went out.
U turn on the memory card to run code show that this board repair
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