【does not boot, no pain maintenance standby
Model P845LM
Appearance hit values are no problem. So electricity. See test card 3.3VSB light does not shine, so Voltage measuring A14 found that only about 0.4V
Unplug the power to run line, on-board to find standby voltage generator components found two 2222, so a pen then A14. Another pen to draw the pin 2222 and found similarities, determine that the pipe produces 3.3VSB another 3.3V voltage is generated 1.5VSB. Circuit and 1117 almost 2222, both input and output pins is just not the same. Circuit 2222 is as follows:
Plug Power Measurement 2222 split the normal input pin 5VSB
Test-retest output pin 0.43
Measuring 2 feet to adjust the bridge there are more than 4V. Do not know is not normal
So get rid of 2222 and the partial pressure of direct resistance, a direct change a 1117 up 【cake in this special thanks to brother taught me this hand】
Then see the measure on the lights on the card 3.3VSB
Overjoyed at once point switch depressed or not bright, so he measured 1.5VSB depressed and we have to 1V so unusual about the dozens of blocks for on-board Zhaoa Zhao finally giving me an elite board to find a 2222. Immediately removed to change generate 1.5V SB out of that tube into a power-on test voltage of about 1.46V voltage that is almost forgotten the occasion of excitement 【beat map, alas .. a flaw】, so rapid heart beat, power-point PWSW, Kuangyun Or did not respond, so suspect that there are problems IO 【83627】 measured IO working conditions, the first test found to 5V normal 72PIN
Measuring 68PIN point PWSW normal hopping
Measuring 67PIN 3.3V for normal
Measuring 67PIN 3.3V for normal
Test-retest 73PIN found to OV
Last pick to open 73PIN pin pad test result was found, or 0V to determine the working conditions of SB Standby is not yet complete. After the investigation the work of a good weld SB measurement of the first CMOS-hop cap at 0.5V voltage is found to be clear about the unusual
Jump test 1PIN cap removed or only about 0.5V, CMOS Circuit concluded that there are problems
First, voltage is measured voltage of about 3V, normal. Then ran a direct line of battery cathode 3.3VSB Short feet enter the normal diode
First, voltage is measured voltage of about 3V, normal. Then ran a direct line of battery cathode 3.3VSB Short feet enter the normal diode
Test-retest diode output is also normal
Then a rerun line diode output into one end of resistor 102 resistor for 3.3V to 0.5V or so out of one end of the 102 suspected and then measuring voltage 3.3V to replace the bad out
Test-retest hop cap at 3.3V supply voltage with the ecstasy
CMOS circuit is as follows:
Test-retest hop cap at 3.3V supply voltage with the ecstasy
CMOS circuit is as follows:
Power-point switch triggered by light aircraft to run this board repair yards
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