- 25/2/15
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- #1
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mohkamtech
Got dead Acer aspire 5738Z for repair.
Platform : JV50-MV M92MB (discrete)
Changed shorted U41, now lap is powering up with no display.
VCC_Core : 0.98V
VGA_Core : 0V ?? though U41 already changed.
Checked working conditions of U45 :
VDD : +5V
EN_VGA=+3.3V
TON : +0.9V ??
P.S note that BOOT is ok +5V
1*-I guess TON should be +19V; Do you agree ?
Changing U45 RT8202 to RT8204 at hand, did not help : always no voltage output and TON remains +0.9V
Lifted one side of L19 and measured resistance to gnd :
-before L19 : over 6Kohms
-after L19 : 3 to 4 Ohms ?
2*- Is 3 to 4 Ohms resistance correct for VGA_Core output,or is it too low ??
3*-Please suggest any new step to take to solve VGA_Core output fail ?
4*- As VGA_Core is failing, and for further diagnose purpose, is their any risk to supply temporarily +1V to VGA_Core output with L19 removed and power up lap ?
Your urgent reply is appreciated
Thank you
Отредактировано mohkamtun (2015-04-29 22:43:54)
Platform : JV50-MV M92MB (discrete)
Changed shorted U41, now lap is powering up with no display.
VCC_Core : 0.98V
VGA_Core : 0V ?? though U41 already changed.
Checked working conditions of U45 :
VDD : +5V
EN_VGA=+3.3V
TON : +0.9V ??
P.S note that BOOT is ok +5V
1*-I guess TON should be +19V; Do you agree ?
Changing U45 RT8202 to RT8204 at hand, did not help : always no voltage output and TON remains +0.9V
Lifted one side of L19 and measured resistance to gnd :
-before L19 : over 6Kohms
-after L19 : 3 to 4 Ohms ?
2*- Is 3 to 4 Ohms resistance correct for VGA_Core output,or is it too low ??
3*-Please suggest any new step to take to solve VGA_Core output fail ?
4*- As VGA_Core is failing, and for further diagnose purpose, is their any risk to supply temporarily +1V to VGA_Core output with L19 removed and power up lap ?
Your urgent reply is appreciated
Thank you
Отредактировано mohkamtun (2015-04-29 22:43:54)