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audiomodder
Senior Member
Last Activity: 05-25-2024, 04:00 AM
Joined: 12-24-2017
Location: California
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what an awesome post and share. THANK YOU...
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Re: Macbook Air 13ich A1466 trackpad 923-0438 and keyboard schematic request
Good news my friend, I had this same problem and reverse engineered the protocol completely. I documented how the keyboard interface works and how you can measure and repair / workaround the power key, in exhaustive detail here:
[URL]https://www.youtube.com/watch?v=3QbX2XuuY8w[/URL]
All repair docs: ********************
(also attached here)
Some summary from Readme:
1. SMC_ONOFF_L goes low to turn on SMC/CPU
this comes directly from keyboard...Last edited by SMDFlea; 01-01-2024, 12:26 PM.Leave a comment:
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Re: Lenovo x1 carbon Gen 2 No POST Dislay
Okay, I attempted to reflow… Results are mixed.
Now the system gives me a blink code for the battery no longer enters an endless power on/off boot loop.
However, I get nothing on the screen (no post) and it will not shut off if I push the power button again, I have to hold it down to do a full system shut off.
I tried hooking it up to an external HDMI monitoring got nothing there as well. Same with display port
Keyboard lights up and keyboard dimming controls work.
Any...Last edited by audiomodder; 10-22-2020, 03:31 PM.Leave a comment:
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Re: Lenovo Carbon X1 12298-2 LMQ-1 48.4LY06 Boardview/Schem?
Okay, I attempted to reflow… Results are mixed.
Now the system gives me a blink code for the battery no longer enters an endless power on/off boot loop.
However, I get nothing on the screen (no post) and it will not shut off if I push the power button again, I have to hold it down to do a full system shut off.
I tried hooking it up to an external HDMI monitoring got nothing there as well.
Any ideas? I'm wondering if I should attempt to reflow again or if maybe there's...Leave a comment:
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Re: Lenovo Carbon X1 12298-2 LMQ-1 48.4LY06 Boardview/Schem?
I have an e-wasted unit with the exact same issue as the original poster. From what I'm reading here and on YouTube, this appears to be a RAM reflow issue.
I can only speak for myself here, but I almost never see these kind of symptoms happen from a bad bios chip. There seems to be an unusual amount of emphasis on BIOS chips here in general
Youtube video: [url]https://m.youtube.com/watch?v=gRddJV3uya4[/url]
LOL welcome to the club! hehe.
...Last edited by audiomodder; 10-18-2020, 03:53 PM.Leave a comment:
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Re: Lenovo x1 carbon Gen 2 No POST Dislay
thanks so much!
Heat but no reflow tho...? Seems a bit strange. Sounds like this is fixing cold solder joints, classic reflow issue. If it's not reflowing, what would "heat" do?
Any links to this known issue? I couldn't come up with anything.
Really appreciate your help
...
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Re: Lenovo x1 carbon Gen 2 No POST Dislay
I have the same issue. Boots, keyboard lights, fan spin
NO display backlight, post, or sound..
after 2 seconds it does a hard shut off.
Tried reset and battery disconnect.
Suspecting GPU or RAM...
anyone repair one?
Leave a comment:
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Re: Asus K56CB schemaics
thank you so much everyone for these schematics and info!!!
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Re: Nexus 5 BATT_ID issue
traced everything out and I think it must be the GPIO pins on the MCU. cant fix it without painful BGA work :/Leave a comment:
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Nexus 5 BATT_ID issue
Hey folks,
I have a used Nexus 5 motherboard I bought with a ripped out battery connector. Replaced the connector but phone won't start unless VBATT_THERM is disconnected. Then it seems to work fine but of course only shows 0% charge. Did factory reset and it does detect the charger.
I've tried 3x batteries and they all measure ~68Kohms to ground on that pin.
To make matters weirder, BATT_ID is grounded on the battery itself, I cannot understand why they even bothered with it connecting to the MCU. VBATT_THERM (i.e. VBAT_THRM) also connects to the MCU.
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Re: Weird issue with parallel Li Ion (need help with board design!)
Thanks for the suggestions everyone.
As I am making this board for production, removing / modifying the Lipo PCB really isn't a good alternative at all. I plan to sell 100s of these.
I seem to have fixed the issue though. Not entirely sure how, but what I did was:
1) matched new connectors / cables for each battery (same length, too)
2) rebalanced both batteries (charged each separately
3) added much larger cap (470uf instead of 100uf) to audio board
So far,...Leave a comment:
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Weird issue with parallel Li Ion (need help with board design!)
Hey all-
So I have a very strange issue I need help with. It has to do with connecting 2 of these in parallel:
[url]https://www.ebay.com/itm/10pcs-LiPolymer-Liion-Rechargeable-Battery-Cell-For-GPS-PSP-3-7V-1500mAh-504050/192181902398?ssPageName=STRK%3AMEBIDX%3AIT&_trksid=p2060353.m1438.l2649[/url]
They have a protection board for each of them, the DW01-P (attached).
I am using this to power a small audio / video device that consumes < 2A from the both of them (total). There was a lot of background noise / audio rippley distortion crap that... -
Re: Macbook Pro 3V42 only 30ohms to GND
U6990 is definitely /not/ supposed to be getting 17V from DCIN. it is not a step down converter. It gets 3V3 from U6901....
what is your pin 1 on U6990?
"Pin 7 was getting 17V but like I say, 0 on pin 4. "
pin 7 of what??
Please start a new thread, you issues are different from what I am dealing with. You should watch videos on the one wire circuit by Louis Rossman as well, to get a better understanding of it.Leave a comment:
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Re: Macbook Pro A1286 820-2850-A
OK good. sounds like you have 2 issues:
1) bad charging circuit somewhere
2) LCD issue (which could be a number of things)
lets fix the charging circuit first.
What is:
CHGR_ACIN
SMC_BC_ACOK
resistance values for:
R6929
R7021
R7022
R7051
R7052Leave a comment:
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Re: Macbook Pro 3V42 only 30ohms to GND
after checking some parts and putting caps back I now get no green light BUT it still boots and works like normal on battery(?) and still 30ohms to ground on 3V42...strange.
BC_ACOK ranges from 2.1V - 3V now so Im thinking U7000 is dead. I already swapped in another U6901 and U6900.
Half the time I plug in the charger PPBUS_G3H reads uot a steady 12.55V. Sense circuits check out OK too. ACIN = 4V. Man, I'm not sure what happened :/Leave a comment:
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Re: Macbook Pro 3V42 only 30ohms to GND
liquid damage wasnt near SMC. it was all around U7000...
U2600 (clock chip) could be the culprit just as the much as the smc and caps i guess. But I dont want to reflow anything unless a last resort.
just strange that it works perfect minus the battery discharge issue. Almost thinking of building a FET control PCB or something as a workaround. obviously thats more work though.Leave a comment:
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Macbook Pro 3V42 only 30ohms to GND
This is a weird one. Got a super damaged 2012 i5 820-3115-B I saved from a ton of water damage. Boots up and works fine now except battery drains to 0% in 1-2 days when turned off. Discovered 30ohms to GND on 3V42 which would clearly cause this.
U7000, U4650, and U6901 all checked out fine. Really worried this might be the SMC. Have a few more caps to check first...anyone have experience with this or know where to look? -
Re: 820-2915-B Trackpad / Keyboard Woes
Replacing CY8C24794 (U7501) did the trick (PSOC USB controller). Holy hell was that not a fun job though. It took me a while before realizing the heatsink on the back had to be removed because it was sucking away all the heat from the GND plane under U7501. Eventually I said "screw it!" and drilled a hole into the center of the chip so I could reach the ground pad. I couldnt remove it otherwise, even after 10minutes + on direct 450 degree heat from a quality reflow station.
Works now tho, so yay!Leave a comment:
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Re: Macbook Pro A1286 820-2850-A
OK tell me exact voltages for:
PBUS_G3H
LCD_PWR_EN
PP5V_S3
PP3V3_S3
PP1V5_S3
LVDS_DDC_CLK
LVDS_DDC_DATA
then maybe:
BKLT_PLT_RST_L
LCD_BKLT_ENLeave a comment:
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Re: LA-6131P / Dell Inspiron 1121 Schems / Boardview?
Found the LA-6132P which is close enough. The motherload of TONS of Compal / Dell schematics:
[url]http://www.s-manuals.com/motherboard/compal?page=11[/url]Re: LA-6131P / Dell Inspiron 1121 Sc...?page=11[/url]Leave a comment:
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