grimacelord
Badcaps Veteran
Last Activity: 07-28-2025, 02:31 PM
Joined: 01-21-2017
Location: Atlanta, GA
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Will do! I will order some today and let you know in a couple of days once I receive it. Thanks!... -
The donor component is currently installed on the board. It was pulled from an identical board. I haven't yet purchased any components for this repair yet.
The datasheet can be found here...Leave a comment:
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Yes, UD201 was replaced with a donor from a donor board, but admittedly, the donor component may have been defective itself. I am not sure. Neither the original component nor the donor is working. I have already sourced a replacement at Digikey. Do you think it would make sense to buy new ones at this point?...Leave a comment:
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Both of those resistors read 6.7kohms, but the schematic says that they should be 4.7kohms. I checked my donor board and they read 6.7kohms on that board as well. A different thread I was reading on here from another user also reported his resistors to be 6.7kohms as well so I don't know if the schematic is correctly reporting the true value or not.
UD201: (The pins themselves are inaccessible under the chip, so I have to measure from nearby components)
Pin 3 (as measured by Pin 2 of RD200 next to it) - 1.25V
Pin 4 - (as measured by Pin 2 of RD201 next to it) - 1.25V...Leave a comment:
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In Ohms scale:
RD208 - (I2C_SMC_PWR_3V3_SCA) - OL
RD207 (I2C_SMC_PWR_3V3_SCL) - OL
If I switch the multimeter to Auto-Range, it reads:
RD208 - (I2C_SMC_PWR_3V3_SCA) - 4.55 MOhm
RD207 (I2C_SMC_PWR_3V3_SCL) - 4.44 MOhm...Leave a comment:
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Both resistors read 3.23V although they are not stable and fluctuate between 3.22-3.23V, barely a difference but I figured it might be worth pointing out. Either way, they're still not 3.3V, as they should be....Leave a comment:
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Our schematics seem to have components labeled differently from one another. Mine has different labeling than yours. See attachment.
Yes, BOTH components "UD___" are on the board....Leave a comment:
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Would the required pull-up resistors for these lines be RD207 and RD208? If so, both of those resistors read 6.7kohms, but the schematic says that they should be 4.7kohms. I checked my donor board and they read 6.7kohms on that board as well. Also, if those are the correct resistors, then to me, it looks like PP3V3_AON is the voltage rail for those resistors and I do have 3.3V on that rail.
So if all of that looks alright, could it be that UD201 and U5150 I pulled from the donor board may have also been faulty or would truly faulty UD201 and U5150​ present itself differently from...Last edited by grimacelord; 07-25-2025, 02:18 PM.Leave a comment:
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Also, I tested for continuity from the test points on the logic board for both I2C_SMC_PWR_3V3_SDA and I2C_SMC_PWR_3V3_SDL to the battery side of the flex cable connector to make sure J5151 was soldered on well and the battery flex cable isn't broken and it's not. There is continuity.Leave a comment:
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Back again. Not quite fixed. Removing J5151 did indeed clear the short, but it hasn't fixed the problem of the computer not detecting the battery. I soldered a brand new J5151 connector onto the board, reassembled everything, and the computer still does not detect a battery and the fan spins high. I decided to measure the voltage this time and here is what I have:
I2C_SMC_PWR_3V3_SDA - 0.735V
I2C_SMC_PWR_3V3_SDL - 0.735V
PP3V3_AON - 3.3V
I did change UD201 and U5150 from a donor board, but it made no difference at all. I suppose they could have been bad components...Last edited by grimacelord; 07-25-2025, 10:03 AM.Leave a comment:
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Wow. That was it. The connector was the problem. As soon as I removed the connector J5151, the short cleared. Thanks for your help mon2. Solved.Leave a comment:
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The only other thing I can think of is the battery flex cable connector itself, J5151. I have removed all of the components on the I2C_SMC_PWR_3V3_SDA line that could be responsible for bringing it short to ground and the short is still there. The only component I haven't removed yet is J5151. Could that be the culprit? And if not, what else could it be? Internal short?...Leave a comment:
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I2C_SMC_PWR_3V3_SCL - (In Ohms scale on my multimeter) reads 0L. (if I set to auto-range - 13.53kohms)
I2C_SMC_PWR_3V3_SDA - 11.4 Ohms
Attached are pictures from the two areas as requested. Please disregard my flux stains that surrounds the area. I will clean that up later. I tried to cleanup the area you're interested in a bit with some isopropyl alcohol so what you're seeing surrounding the area is flux....Leave a comment:
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A2338 820-02020-A | Battery Not Detected/Random Reboots
Hello,
I have a A2338 MacBook Pro here that came to me because the battery wasn't being detected. The owner tried to replace the battery themselves thinking that the battery was the problem but the behavior continues even with their new aftermarket battery. They also accidentally ripped off the black plastic clasp to the battery flex cable connector @ J5151, but I pulled that off of a donor board and replaced that for them already. I did quickly check to see if that was simply the problem, but it's not.
First thing I checked was I2C_SMC_PWR_3V3_SCL and I2C_SMC_PWR_3V... -
Hello again,
I finally was able to give this another try, but unfortunately, I still have no POST.
I first flashed your files to each respective BIOS chip and then disconnected everything except for the essentials. Motherboard, CPU, a single stick of RAM in slot A2, and of course the power supply. I then cleared CMOS using the jumper on the motherboard, connected power, and powered on the computer and allowed it to try and POST for about 10 minutes the first time. Then, I shut down the computer, tried adding a GPU card and switched the HDMI cable to that, CMOS clear again,...Leave a comment:
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Thank you again for your help. I won't be able to get back to this until Monday, but I'll try this first thing Monday morning and let you know how it goes. Have a great weekend!...Leave a comment:
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I went back and tried this method and the resulting 8MB image I came up with was identical in hex to the first 8MB image I created, but the second 16MB image I made using the method above was different than the 16MB image I created the first time. I went back and flashed that 16MB image, hoping that I found my error, and still - no POST. Just figured I'd let you know everything that I have done. I'm still no closer to figuring this out myself, so I hope you are able and willing to help me. Thank you again....Leave a comment:
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Well, looks like I botched it again somehow. I felt like everything was going smoothly and I was getting the exact file sizes that you said I should, but I think I must've made an error when splitting my "full bios" file I created as per your instructions. After flashing my "split image" to each chip and attempting to boot, the computer doesn't POST.
I am attaching my new dumps that I took after I set the frequency to 8MHz (verified with 3 dumps) and I am also attaching my "full bios image" I created according to your instructions as well as my "16mb.bin"...Leave a comment:
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Thank you for the help. I also use the T48 and I indeed used a clip on both dumps. I'll try again with a lower frequency as you suggested and see if the dumps are the same after 3 reads.
As far as the process goes, thank you for explaining that so clearly. I think I might be able to follow that. I'm going to give it a try and if I fail miserably as I have in the past at this sort of thing, I'll post back with fresh dumps and maybe you could give it a try? Haha.
I really appreciate your help. I'll be giving this a try in about an hour...Leave a comment:
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ASUS TUF GAMING Z790-PLUS WIFI - BIOS Help
Hello,
I have spent the last hour on this and I guess this is just over my head, so here I am.
I have an ASUS TUF GAMING Z790-PLUS WIFI motherboard here that needs to have the BIOS updated in order to accept the latest CPUs.
The BIOS chips seem to come as a set of two: GD25B64ESIG and GD25B128ESIG. My guess is one of them is a fail-safe for the main BIOS? I really don't know. Or one of them is ME and other is BIOS? I don't know.
Anyway, I took dumps of both chips and then downloaded the latest update for this motherboard from ASUS's website...
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