Re: 820-02020 No backlight 0,8v on BKLT_EN_R
Back at it again! Was on a holiday. Got my small LCD cable but still no luck. Now im thinking this was the problem all along... But while I was looking somewhere else I destroyed something!
I noticed that RP842 pin 1 has a diode mode reading 0.019 and 0v which was 0.187 and 0.8v. But should have been 0.375.
When I remove RP842 I can see diode mode reading of pin 2 is 0.575 and pin 1 is 0.019! im really out of ideas now!...
hassie2001@gmail.com
Member
Last Activity: 03-19-2025, 09:42 AM
Joined: 08-12-2020
Location: Vlaardingen
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Re: 820-02020 No backlight 0,8v on BKLT_EN_R
Don't think this is correct.
As per schematic, VIH=1.2V; so it comes from 1.8V powered logic.
0.82V is prohibited value, can't be correctly recognized.
0 logic is between 0-0.4V and 1 logic is 1.2-1.8V......Leave a comment:
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Re: 820-02020 No backlight 0,8v on BKLT_EN_R
Figured out something else! On the small lcd flexcable pin 24 is broken. On the connector on the logicboard I get a good diode measurement (0.507) but when I connect the small lcd flex cable I get a O/L on the other side... So the LCD doesn't get a connection!
Tried different Flex cables but when I use another one I don't get image. Is there a difference between the M1 small lcd flex cable and the once before the m1?
To bad I only have 1 M1 here, so can't check... Maybe I can try to repair the flex cable?!...Leave a comment:
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Re: 820-02020 No backlight 0,8v on BKLT_EN_R
Tried but no luck! What I noticed is that
“RP851 starts with 5.1v as soon as image apears goes to 4.8v” this is not 4.8v it stays 5.1v.
But the scl line still starts with 5.1v and goes to 4.8v. So as I understand there is no good communication…
What can I look at more?!?Leave a comment:
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Re: 820-02020 No backlight 0,8v on BKLT_EN_R
Source 12v
Gate 11,9v
Drain 0v
No shorts...Leave a comment:
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Re: 820-02020 No backlight 0,8v on BKLT_EN_R
RP850 (BKLT_SCL) starts with 5.1v as soon as image apears goes to 4.9v, diode mode 0.491
RP851 (BKLT_SDA) starts with 5.1v as soon as image apears goes to 4.8v, diode mode 0.491Leave a comment:
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Re: 820-02020 No backlight 0,8v on BKLT_EN_R
The enable signal (BL_PWR_EN) comes directly from u8100, does that mean that u8100 is failing? It produces 0.8v but not enough to logic high (1.2v-1.8v)? There was some corrosion between pin 18 and 17 of UP800 so maybe 5v went to pin 17 and directly to u8100... Can't I just boost the low signal u8100 is giving to 1.8v?
The board works perfectly on an external display even on internal perfect without backlight! So this is my only dilemma!
The tested screens are all a2338 Screens from previous repairs....Leave a comment:
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Re: 820-02020 No backlight 0,8v on BKLT_EN_R
I guess you meant RP842.
Here are the Diode mode readings
RP842 pin 1 0.170 (BL_PWR_EN) I'm thinking something here is wrong...
RP842 pin 2 0.516 (BKLT_EN_R)Leave a comment:
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Re: 820-02020 No backlight 0,8v on BKLT_EN_R
board is out of housing, so no trackpad connected
[url]https://photos.app.goo.gl/qvWHaGg9jyct71YH9[/url]Re: 820-02020 No backlight 0,8v on B...yct71YH9[/url]Leave a comment:
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Re: 820-02020 No backlight 0,8v on BKLT_EN_R
Thank you for the reply, I already checked IPD_LID_OPEN_1V8 As I read many of your posts on this forum! (great job by the way). it is 1.8VLast edited by hassie2001@gmail.com; 02-09-2023, 08:54 AM.Leave a comment:
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820-02020 No backlight 0,8v on BKLT_EN_R
Hi,
I have no backlight on my screen, tested with 2 different known working screens. Logicboard is perfect clean no traces of liquid only on pin 17 en 18 of UP800. Got chip off and saw that pin 18 was corroded bad. Cleaned it and replaced UP800 with one from 820-01598 (according to PDF, same model) Chip should get 5v.
Diode mode readings are ok except for pin 17 and 4
Pin 17 (BKLT_EN_R) is 0.187 should be 0.374 and give 0,82v
Pin 4 (LCDBKLT_FET_DRV) is 0.422 should be 0.550 (According to PLDaniels database).
Could it be that UP800... -
Re: A2159 MacBook Pro (13-inch, 2019) 820-01598-06
Thanks!!Leave a comment:
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