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Old 04-14-2021, 02:59 PM   #1
CornholioGSM
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Default Lenovo 330- NM-B661 - No display, No touchpad

Hello,
I need help with Nm-B661 mainboard.
PU3501 was burned and changed with new one. I am now able to turn on laptop but without picture on display - no image no backlight and nothing on +LCDVDD_CON.
Display connected to hdmi works fine.
For me it looks like +3VS line - i can measure only around 1.9-2V.
+LCDVDD is connected to U9 (SY6288C)...and i have on INput again 1.9V and on EN i have 3.3V...but nothing on OUTput
.....and no touchpad too...but is again powered from +3VS.
*measured without connected display cable

please help

Last edited by CornholioGSM; 04-14-2021 at 03:07 PM..
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Old 04-14-2021, 11:10 PM   #2
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Default Re: Lenovo 330- NM-B661 - No display, No touchpad

+3VS is generated from PU3501, pin29 and +5VS from Pin28. So remove jumper PJ3506 or cut the track on output side to see if you get stable +3VS on pin29 of PU3501.
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Old 04-15-2021, 01:16 PM   #3
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Default Re: Lenovo 330- NM-B661 - No display, No touchpad

Quote:
Originally Posted by mcplslg123 View Post
+3VS is generated from PU3501, pin29 and +5VS from Pin28. So remove jumper PJ3506 or cut the track on output side to see if you get stable +3VS on pin29 of PU3501.
hmmm...line cutted and i can measure 5.6V on pin29 and on another side 1.9V

Last edited by CornholioGSM; 04-15-2021 at 01:18 PM..
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Old 04-15-2021, 10:55 PM   #4
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Default Re: Lenovo 330- NM-B661 - No display, No touchpad

Are you sure you are getting 5.6V on pin29 as you are supposed to get 3.3V there. Another question, if you have cut the track how you can get any voltage on the other side?? You are saying you get 1.9V on the cut track which is impossible to explain. So , i think you have cut the track on wrong place. Check again.
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Old 04-18-2021, 12:50 PM   #5
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Default Re: Lenovo 330- NM-B661 - No display, No touchpad

Quote:
Originally Posted by mcplslg123 View Post
Are you sure you are getting 5.6V on pin29 as you are supposed to get 3.3V there. Another question, if you have cut the track how you can get any voltage on the other side?? You are saying you get 1.9V on the cut track which is impossible to explain. So , i think you have cut the track on wrong place. Check again.
....i mean that is nothing to check again.
I have same result .... same on desoldered jumper or on cutted line
On output from PU3501 i have 5.7V....on other side 1.9V...really


BTW question...original PU3501 (LV5083A) was marked as 0M=5C...but new one is 0M=5F...is it really same?
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Last edited by CornholioGSM; 04-18-2021 at 01:09 PM..
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Old 04-18-2021, 10:54 PM   #6
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Default Re: Lenovo 330- NM-B661 - No display, No touchpad

I beleive the first two letters only matters, so the IC is likely same. I still could'nt understand how you can get voltage on a disconnected line(1.9V). the output on pin29 is way too high at 5.6/5.7V. May be the replacement IC is bad or not properly soldered. I'm still puzzled at voltage on pin29 and honestly speaking dont know why the voltage is so high there.
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