DadBuk
Member
Last Activity: 03-28-2022, 03:01 PM
Joined: 09-03-2021
Location: Brisbane, QLD
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What is a good current sense reading
Hi, have searched high and low for some info on what a good current sense reading is as it applies to MacBooks. On a MacBook there are many isense signals and it seems logical that the higher the voltage of that signal then the more current is flowing through that rail. What I have not been able to determine from the schematics or from searching the forums is the voltage range of a current that is in spec versus one that is out of spec and therefore causes the MacBook to take some action. I see in the schematics there are values for the max current on a rail but nothing that looks to be the voltage... -
Re: Mid 2015 15" Retina Pro green light but won't start
Back to this board again.
Not sure whether there are voltage oscillations on pins 1 & 2 of U6100 - there is a spike each time the board cycles - I have attached 3 screen prints for pins 1 - 3 which all look similar. My scope has SPI but is 2 channel so can only decode one at a time and cannot use CS. I set it up on pin 2 SPI_MLB_IO1_MISO on channel 1 and pin 6 SPI_MLB_CLK on channel 2 (first time doing this so hoping that is correct) with a timeout of 2.2us but there is no decoding - just a flat line... -
Re: Mid 2015 15" Retina Pro green light but won't start
Hi,
Here are the measurements for U6100 and U6101. Thanks
U6100
1 SPI_MLBROM_CS_L = 3.32
2 SPI_MLB_IO1_MISO = 3.31
3 SPI_MLB_IO2_WP_L = 3.32
4 GND
5 SPI_MLB_IO0_MOSI = 3.31 / 0
6 SPI_MLB_CLK = 3.31 / 0
7 SPI_MLB_IO3_HOLD_L = 3.32 / 0
8 PP3V3_SUS = 3.31
9 GND
U6101
1 GND
2 PP3V3_SUS = 3.32
3 SPI_MLB_CS_L = 3.28
4 GND
5 SPIROM_USE_MLB = 3.28
6 GND
7 SPI_MLBROM_CS_L = 3.32
8 PP3V3_SUS...Leave a comment:
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Re: Mid 2015 15" Retina Pro green light but won't start
Hi, further to my update above, I was going over this startup sequence [url]https://logi.wiki/index.php/G3_to_S3_State_for_Ivy_Bridge_Haswell_and_Broadwell[/url] to see where this board gets to. Everything checks out down to PM_SLP_S5_L which is pulsing 3.3v - 0.v as is PM_SLP_S4_L. As mentioned above all the power rails from S4 down are also pulsing.
Any ideas on what else I could check on this board.
ThanksRe: Mid 2015 15" Retina Pro green li...> Hi, furtherLeave a comment:
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Re: Mid 2015 15" Retina Pro green light but won't start
Hi,
those measures are:
a) L7630 pin 2 PP1V05_S0_REG_R = 1.04v pulsing to 0v
b) after the current sense resistor (R7640) = 1.04v pulsing to 0v
c/d/e)
Pin 1 (G1) P1V05S0_DRVH = 1.05v pulsing to 0v
Pins 2, 3, 4, 9 (D1) PPVIN_S5_HS_COMPUTING_ISNS = 12.59v constant
Pins 5, 6, 7 (S2) GND = 0v
Pin 8 (G2) P1V05S0_DRVL = .22v pulsing to 0
Pin 10 (S1/D2) PP1V05S0_LL = 1.04 pulsing to 0
PP1V05_S0 to ground = 64ohm
...Leave a comment:
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Re: Mid 2015 15" Retina Pro green light but won't start
Hi, just an update.
Q7630 does seem to be defective. It is a dual N channel power mosfet. First channel has a voltage drop of .454v D-S and open S-D and high resistance . Second channel has voltage drop .053v D-S and .039v S-D and 60-70 ohm resistance both ways.
So I guess next steps would be to source a replacement for it and U7600 as I read somewhere a damaged mosfet can damage the IC. Q7630 is a NTMFD4951NF but that part number does not come up to buy. I read that any 2 channel mosfet...Leave a comment:
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Re: Mid 2015 15" Retina Pro green light but won't start
Thanks Mon2.
At the moment I am having problems with my USB microscope - it is one of those converted Microsoft LifeCams - so gives a reasonable view of the components but the driver has started to crash after about 15 secs making things difficult. For the moment I am using a Supereyes usb microscope and have a trinocular microscope on the way.
In the meantime - I have been looking through the schematic and there are many sense circuits, most not on the main power rails I think. Were there...Leave a comment:
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Re: Mid 2015 15" Retina Pro green light but won't start
I checked all the coils and the readings were consistent with the rails measurements except for L6604/L6605, L6611/L6614 being 0Ω and L6606/L6607 being OL - but that is all audio stuff so I am guessing it is not related to the cycling power rails and the coils are more to do with audio. Any suggestions on where to look next would be appreciated.
ThanksLeave a comment:
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Re: Mid 2015 15" Retina Pro green light but won't start
Thankyou for taking the time to reply mon2.
Since starting to look at this board I have been watching a lot of MacBook repair YouTube channels including Paul Daniels - both entertaining and informative.
Due to the cost, for this board I am not planning to send it out again for professional work just in case the first technician was correct and it is not fixable - but am finding the troubleshooting process interesting so will see how far I can get with some more research and some advice from...Leave a comment:
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Mid 2015 15" Retina Pro green light but won't start
Hi,
My son spilt water on the right side (facing the laptop) of his mac. It went for a bit then turned off. I put it in to a local mac repair shop where they put it through the ultrasonic and I am pretty sure they did some soldering on the board but in the end they could not fix it - I don't know much about what they tried, I should have asked more questions at the time but just thought it was terminal. The technician did say that he could have tried injecting some voltage but that would be risky to the CPU.
The service was not a 'no fix, no fee' arrangement so after... -
Re: New Members - please post your introductions here
Hi, Paul here from sunny Brisbane. I have a broken Macbook that I hope to fix with some help from this forum. I have been reading up but am not confident to start injecting voltage without a little bit of advice.Leave a comment:
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