XBox One S - No Power On - Missing 3.3V - Page 1
Forum section: electronics / repair

author: LiftedTrace
author_rank: Regular Contributor
timestamp: November 24, 2019, 06:52:06 pm
content: Hello all, I am at it again. This time a friend of mine came to me with a dead xbox. I figured, its already dead why not poke around and see if I can find out why.Im new to this stuff and would like your input on if what I am thinking is correct.I started by checking if the main + and - were shorted, and they were not.I plugged in 12V to the main and started checking voltages at the test points. I have the 12V and 5V but not the 3.3V.The main 3.3V comes from the 12V it seems from what I show in the pictures. I am getting .8V on the output of the coil. SO i was thinking, maybe something is shorted, dropping the 3.3 down to .8, so I decided to put 3.3V directly on the test point to check if the voltage got pulled down, and it did not, and drew very little current.Seen as there is not much around this area, I was suspecting this little chip is not working as expected and not producing its 3.3V.Your thoughts?I also have no clue what this chip is, I cannot find any info on it to really test further.Anyone have any direction I can go?

author: fzabkar
author_rank: Super Contributor
timestamp: November 24, 2019, 07:20:57 pm
content: NB671GQ, Monolithic Power, Synchronous Step-down Converter, 5V - 24Vin, 6A, marking AEAy, QFN-16:http://www.mouser.com/ds/2/277/NB671_r1.04-371602.pdfCheck the Enable pin to see whether the IC is being switched on.

author: LiftedTrace
author_rank: Regular Contributor
timestamp: November 24, 2019, 10:05:03 pm
content: Awesome, Thank you.I checked the enable pin and its low (.09V). So now I just have to try and find what is supplying that voltage. I have no clue where its coming from and it very quickly vanishes thru the board.Looks like I have a nice hunt on my hands.I'm half tempted to open mine up and take some reference measurements.I'm afraid it might be coming from one of the main chips and if thats dead, maybe thats why its not enabling the 3.3V

author: fzabkar
author_rank: Super Contributor
timestamp: November 24, 2019, 10:08:08 pm
content: Could we see a photo of the whole PCB?

author: LiftedTrace
author_rank: Regular Contributor
timestamp: November 24, 2019, 10:44:06 pm
content: Absolutely. Here is the front and back. If you would like higher res, let me know. This is as good as my phone takes.I marked the chip that provides the 3.3 with a red X....upper left side of the board on the front.

author: LiftedTrace
author_rank: Regular Contributor
timestamp: November 24, 2019, 10:50:43 pm
content: I poked around the near by power supplies with the continuity mode, trying to poke everything I seen to try and find where that enable trace is going off to, but I didn't find anything.

author: fzabkar
author_rank: Super Contributor
timestamp: November 25, 2019, 12:35:20 am
content: Does the IC get a proper Vin supply?I would measure the voltages at the large electrolytic capacitors, both leaded and surface mounted. Also measure the voltages at the inductors (Lnnn). These will be the inputs and outputs of the various switchmode regulators.Also check the fuses, eg RT3F1, RT6B1, RT6B2. These have a Littelfuse logo (Lf).There are several 5-pin chips which look like linear regulators or maybe load switches, eg U5D2 and two others near the bottom left edge of the PCB. Can you measure their inputs and outputs? Can you identify their part markings?

author: fzabkar
author_rank: Super Contributor
timestamp: November 25, 2019, 12:57:25 am
content: I though this thread looked familiar ...https://www.eevblog.com/forum/repair/xbox-one-s-repair-(ebay-project)/

author: LiftedTrace
author_rank: Regular Contributor
timestamp: November 25, 2019, 01:22:06 am
content: Yeah that was my failed attempt at trying to repair an ebay item. It was a lost cause. This one of my friends my be a lost cause too.

author: fzabkar
author_rank: Super Contributor
timestamp: November 25, 2019, 01:35:08 am
content: If you want to keep plugging away, we'll see how far we get this time.

author: LiftedTrace
author_rank: Regular Contributor
timestamp: November 25, 2019, 02:07:02 am
content: Ok so, The Vin on the suspect chip is a solid 12V. The enable pin is not getting its voltage and I do not know where its coming from yet.U5D2 looks to be getting its input from the output of the large coil next to the chip with the red X on top (the chip not getting its enable voltage)U5D2 has no output voltage.The two identical 5pin chips in the lower left also get their input from the large coil next to the red marked chip. These also have no output on them.There is a dead short between the output of the coil and the inputs of those chips. I gave the 3.3v test point a low limited current 3.3v and I didn't see any drop in voltage, so I don't think something on the 3.3v side is pulling it down.Oh and all the fuses checked out good.This site:https://www.electronicproducts.com/Xbox_One-whatsinside_text-158.aspxWas pretty helpful in finding some stuff, like them lower left 5 pin chips.These chips were marked with: P6243WG and that site lists its part number as CAT6243DCADJ?RKGChip labeled U5D2 has marking of GK1DQ828 and I cannot find any info on this, but I assumed the input was the pin with the same voltages as the inputs on the other two chips and what the large coil was outputting.

author: LiftedTrace
author_rank: Regular Contributor
timestamp: November 25, 2019, 02:08:36 am
content: QuoteI enjoy this, Illuntil all options are exhausted

author: fzabkar
author_rank: Super Contributor
timestamp: November 25, 2019, 02:56:57 am
content: That's a great teardown.P6243WG is an adjustable linear regulator with an Enable pin (1). If there is no Vin, I would think that the Enables would be inactive, too.I think if you continue on this path and map out the relationships between each of the supplies, then you can build a picture of the power layout for the PCB. Clearly there must be a main supply which powers whichever chip is responsible for enabling the NB671GQ. Maybe you will find other regulators with missing enables, and this may then give us a better idea of the source.Just keep measuring the coils and large capacitors.Edit:U5D2 is an LDF adjustable regulator. Pin #1 is the enable.LDF, STMicroelectronics, adjustable LDO regulator, 1A, 2.6V - 16Vin, PPAK-5:pdf.datasheetcatalog.com/datasheets/stmicroelectronics/LDF_LDFPT-TR_LDFPVR_LDF33PT-TR_to_LDF25PT-TR.pdfCAT6243DCADJ-RKG, ON Semiconductor, LDO Regulator, Adjustable, 1A, 2%, marking P6243WG, DPAK-5:https://www.onsemi.cn/pub/Collateral/CAT6243-D.PDF

author: LiftedTrace
author_rank: Regular Contributor
timestamp: November 25, 2019, 03:05:49 am
content: Do you think it possible these have the same enable inputs? I i remember correctly, the P6243 didnt have anything on the enable either. I just ignored it cause the Vin was gone too.

author: fzabkar
author_rank: Super Contributor
timestamp: November 25, 2019, 03:20:58 am
content: It would be helpful to know the state of Vin and Enable for each of the regulators. You will find additional switchmode regulators alongside the coils.

author: LiftedTrace
author_rank: Regular Contributor
timestamp: November 25, 2019, 03:31:02 am
content: Quote from: fzabkar on November 25, 2019, 03:20:58 amIll take some readings and document as much as I find. It might be a few days with Thanksgiving coming up and long work days. Il post back as soon as I can.

author: fzabkar
author_rank: Super Contributor
timestamp: November 25, 2019, 03:39:46 am
content: If you can write up the markings on the chips, I can produce a BOM for you. Then you'll have something to work with.

author: LiftedTrace
author_rank: Regular Contributor
timestamp: November 25, 2019, 03:46:36 am
content: Ill take a higher res image and jot down the voltages on the image. any un readable chips, Ill type in over them. Might take me a few days.Thanks for the help.

author: LiftedTrace
author_rank: Regular Contributor
timestamp: November 27, 2019, 04:12:27 am
content: Here is a link to a higher res image:https://www.dropbox.com/s/db9q1sntkaq0whq/XBOX%20Front%20Voltages.jpg?dl=0I took a few measurements and put them on the chips. The font is very small, about the size of the chip leads them selves. You need to zoom all the way in to see them good.I didnt measure the 3.3V chip ( not sure why I didnt do that one first)I find it very strange the EN pin doesnt seem to have any input to it. I cannot find where it goes.The chip itself is getting 12V supplied to it though.I am half tempted to take a resistor and tap off the 12V rail and see if I can even get the chip to turn on and output 3.3 manually.

author: fzabkar
author_rank: Super Contributor
timestamp: November 27, 2019, 10:43:45 am
content: Here is the BOM so far:LDF, STMicroelectronics, adjustable LDO regulator, 1A, 2.6V - 16Vin, PPAK-5:pdf.datasheetcatalog.com/datasheets/stmicroelectronics/LDF_LDFPT-TR_LDFPVR_LDF33PT-TR_to_LDF25PT-TR.pdfCAT6243DCADJ-RKG, ON Semiconductor, LDO Regulator, Adjustable, 1A, 2%, marking P6243WG, DPAK-5:https://www.onsemi.cn/pub/Collateral/CAT6243-D.PDFLM339A, Texas Instruments, precision quad differential comparator, 2V - 36V, +/-1V - +/-18V, marking L339A, SOIC-14:http://www.ti.com/lit/gpn/lm339aTPS51916, Texas Instruments, Complete DDR2, DDR3, DDR3L and DDR4 Memory Power Solution Synchronous Buck Controller, 2-A LDO, Buffered Reference, 3V - 28Vin, 0.7V - 1.8Vout, QFN-20:http://www.ti.com/lit/gpn/tps51916TPS53819A, Texas Instruments, 3V - 28V Input, 40A, Eco-Mode, D-CAP2 Synchronous Buck Controller with PMBus, marking 3819A, QFN-16:http://www.ti.com/lit/gpn/tps53819aSN75DP159, Texas Instruments, 6-Gbps AC-Coupled TMDS to HDMI Level Shifter Retimer, marking 75DP159, WQFN-40:http://www.ti.com/lit/gpn/sn75dp159NT5CB256M16EP-FL, Nanya, DDR3 SDRAM, 4Gb x 16, 1.5V, 2133Mbps, BGA-96:https://www.nanya.com/en/Product/3994/NT5CB256M16EP-FLhttps://dl.khadas.com/Hardware/VIM1/Datasheet/Amlogic_STB_Release_V3.3_QPL20170609-Wesion.pdfAON7403, Alpha and Omega, P-ch MOSFET, -30V, -29A, 18mOhm Rdson, marking 7403, DFN-8:http://www.aosmd.com/res/data_sheets/AON7403.pdfKLM8G1GEME, Samsung, eMMC, 8GB, 64Git x 1:https://www.samsung.com/semiconductor/global.semi/file/resource/2017/11/Samsung_eMMC_2013-0.pdfTHGBMFG6C1LBAIL, Toshiba, eMMC NAND Flash, 8GB, 1 x 64Gbit, 3.3V / 1.8V, BGA-153:https://www.es.co.th/Schemetic/PDF/THGBMFG6C1LBAIL.PDFNTMFS4C55N, ON Semiconductor, N-ch Power MOSFET, 30V, 78A, 3.4mOhm Rdson, marking 4C55N, SO-8:https://media.digikey.com/pdf/Data%20Sheets/ON%20Semiconductor%20PDFs/NTMFS4C55N.PDF1812L150/24, Littelfuse, Polyfuse, 24V, 1.5A, marking LF150-24:http://www.littelfuse.com/products/resettable-ptcs/~/media/Electronics/Datasheets/Resettable_PTCs/Littelfuse_PTC_1812L_Datasheet.pdf.pdfAP2127K-ADJTRG1, Diodes Inc, 300mA HIGH SPEED, EXTREMELY LOW NOISE CMOS LDO REGULATOR, marking GEH, SOT23-5:https://www.diodes.com/assets/Datasheets/AP2127.pdfPMBT2222A, NXP, NPN transistor, 40V, 600mA, marking W1P, SOT23-3:https://assets.nexperia.com/documents/data-sheet/PMBT2222_PMBT2222A.pdfSSM3K324R, Toshiba, n-ch MOSFET, 30V, 4A, 1W, 56mOhm Rdson, marking KFD, SOT23-3F:https://media.digikey.com/pdf/Data%20Sheets/Toshiba%20PDFs/SSM3K324R.pdfSSM3J331R, Toshiba, p-ch MOSFET, -20V, -4A, 55mOhm Rdson, marking KFO, SOT23-3F:https://toshiba.semicon-storage.com/info/docget.jsp?did=13019&prodName=SSM3J331RNCP5901BMNTBG, ON Semiconductor, dual MOSFET gate driver, marking AZx, DFN-8http://www.onsemi.cn/pub_link/Collateral/NCP5901B-D.PDFSP1004U-ULC-04UTG, Littelfuse, TVS Diode Array, 0.20pF, 20kV, 9.2V clamping, marking 4C, 1004 DFN:https://www.littelfuse.com/~/media/electronics/datasheets/tvs_diode_arrays/littelfuse_tvs_diode_array_ultra_low_capacitance_diode_arrays_datasheet.pdf.pdfB130LAW-7-F, Diodes Inc, Schottky rectifier, 30V, 1A, marking SX, SOD123:http://www.diodes.com/datasheets/ds30308.pdfMP8757, Monolithic Power, Synchronous Step-Down Converter, 7A, 5V - 18Vin, marking MPyw + 8757, stepdown converter, QFN-21:https://www.monolithicpower.com/en/documentview/productdocument/index/version/2/document_type/Datasheet/lang/en/sku/MP8757/document_id/905/TPS51206, Texas Instruments, 2A Peak Sink/Source DDR Termination Regulator with VTTREF Buffered Reference for DDR2/3/3L/4, marking 1206, WSON-10:http://www.ti.com/lit/gpn/tps51206SN74LVC1G08DBVR, Texas Instruments, single 2-Input AND Gate, 1.65V - 5.5Vin, marking C08F, SOT-23-5:http://www.ti.com/lit/ds/symlink/sn74lvc1g08.pdfNB671GQ, Monolithic Power, Synchronous Step-down Converter, 5V - 24Vin, 6A, marking AEAy, QFN-16:http://www.mouser.com/ds/2/277/NB671_r1.04-371602.pdfMP2161GJ, Monolithic Power, Synchronous Step Down Switcher, 2A, 2.5V - 6Vin, 1.5MHz, 17uA IQ, marking AEBy, TSOT23-8:https://www.monolithicpower.com/en/documentview/productdocument/index/version/2/document_type/Datasheet/lang/en/sku/MP2161/document_id/450RT5785AGJ8F, Richtek, synchronous step-down DC-DC converter, 2A, 2.5V - 6Vin, 25uA IQ, marking ON=, TSOT-23-8:https://www.richtek.com/assets/product_file/RT5785A=RT5785B/DS5785AB-02.pdf

author: fzabkar
author_rank: Super Contributor
timestamp: November 27, 2019, 11:54:28 am
content: UC43 appears to be configured as a 5V regulator. There is a "5P0" test point below capacitor C4D1. ISTM that this part of the circuit is working correctly.As for the chip's identity, all I know is that it is a stepdown converter made by Monolithic Power.

author: LiftedTrace
author_rank: Regular Contributor
timestamp: November 27, 2019, 02:15:33 pm
content: Yes the 5v seems to be working as expected.I also have the 1.1STBY.Anything that seems to get its main power from that 3.3V is shut down.Now here is a question.U4C2 turns on with a high EN. The data sheet says over 1v with a max of 12.It’s currently got .2v.So if the chip is off, how is it producing .8v on the coil L5C1?I would think L5C1 should be 0v just the the others that are not currently on.

author: fzabkar
author_rank: Super Contributor
timestamp: November 27, 2019, 04:52:20 pm
content: I can't understand why there is 0.8V there, either.I notice that the Vout (pin 5) of U3D6 is low. Is something shorting its output to ground, or is the IC faulty? BTW, I don't see any feedback resistors on pin 4 (ADJ). Perhaps they are on the other side of the PCB?It might help to compare this PCB with your water damaged one. A similar hires photo could help us to identify the date and batch codes from the part markings.Edit:FWIW, page 3 of the Xbox 360 circuit diagrams shows the reset logic for that PCB. Many of the power enables come from its Southbridge, so I'm guessing that the X861949-007 (Microsoft XBOX ONE ASIC) may be the source in our case.https://elektrotanya.com/xbox_360_xenon_retail_rev_k7_fab_k_sch.pdf/download.htmlEdit 2:It may be obvious to some, but the circuit references include the PCB coordinates. I just worked it out now (doh!).The PCB is laid out in a grid consisting of columns numbered from 3 to 9 running from left to right, and rows from B to G running from top to bottom.A part is identified as type-column-row-number.For example, C5E10 is a capacitor, C10, located at column 5, row E.

author: LiftedTrace
author_rank: Regular Contributor
timestamp: November 28, 2019, 03:52:17 am
content: QuoteI had no idea, that's great for pointing that out. Makes for finding things much nicer.So I just spent some time looking thru that xbox break down site and trying to find what ever chip U3d5 was, and the only thing I found was TPS206x in the DVB package. This lists the Output as Pin 1 and the input as Pin 5. I dont think this is the correct chip because I got almost nothing on the input, but almost 5V on the output.I also cannot find out what U4D4 is from that site either.As for the feed back resistors for U3D6, there are two resistors on the back side in very close proximity to the power supply package of components.I am not sure this is where the problem is though, only for the fact that the small coil near all this it outputting 1.136V, and there is a test point right by there labeled TP1P1STBY which has 1.136V on it. Also very close to that is the test point for the 1.8V labeled 1P8STBY (Location TP4D4) which is reporting only .089V. Now Im no expert at this, but if this is a STBY voltage coming from some power supply, should I be reading 1.5_Ohms between this TestPoint and ground?So, I cannot seem to find out where this 3.3V chips EN is coming from which makes me think it may be coming from the big kahuna (U4D2 ) The Xbox One chip. It may be possible that the 1.8V supply is shorted somewhere and the main chips knows it and is not allowing the rest of the machine to power up. If that is the case, How could I find out what is shorted? And is it possible its the main Xbox One chip itself which is shorted?Maybe its time to give the 1.8V a current limited 1.8V on its testpoint and see what gets warm?EDIT:Ok, so I got impatient, I went ahead and gave that 1.8V test point the voltage it was wanting, with a 100ma limited current. There was absolutely no drop in voltage when I gave it 1.8V, and I cant seem to find where its coming from because when I check with Ohms, its virtually a short.I seem to be stuck.EDIT 2:So I connected main power again and now I have 1.8V, and when I measure the resistance (power off) I get 71_Ohms.How is this possible? Go from a dead short, to 71 Ohms?EDIT 3:The 1.8V seems to be coming from U3D6, the one you were saying the Output (pin 5) was a bit low.....its no longer sub .1, but 1.8, and pin 4 is also now at .8vMaybe my hitting the test point with 1.8V scared it straight?The 3.3V is still out of commission though.EDIT 4:Ok so I decided to pullup the enable pin on the 3.3V power supply and see if it kicked on....and it did!But none of the others started working, because they also are missing their enables.I dont know, I am really leaning towards the main Xbox chip being gone. None of the enables are tied together, so they must be getting their input from some control chip. and since there really is not much other than the large XBox chip and some power supplies, I am not sure what more I can do for this thing.I could Frankenstein the thing and force all the chips to turn on by pulling up all their enables.....just to see if it boots, but not sure its worth it.

author: fzabkar
author_rank: Super Contributor
timestamp: November 29, 2019, 09:10:00 am
content: I don't think it is a good idea to backfeed the supply voltage into the outputs of your regulators.Have you checked all the other supply test points? Is your 3.3V supply the only one that is missing now? I suspect that the 1.5 ohm short may have been due to an MLCC (ceramic cap).

author: LiftedTrace
author_rank: Regular Contributor
timestamp: November 29, 2019, 03:55:58 pm
content: There are many that are not turning on, but some of them I suspect will never turn on until the power button is pressed and the whole thing wakes up. I just do not know which ones those are that should be in all the time, and those that only come on at power up.It may be time to take my working one apart and use for a reference.As a side thing, there was clearly something wrong with the output of U3D6, or what ever makes it tick. Do you know the part number of that thing?EDIT 1:Ok well I amWhen it occurred to me that other power supplies were not turning on until power up, I connected the power button board, and low and behold! The 3.3v I was missing suddenly came to lifeThe enables for that 3.3 chip ( U4C2 ) is not present, as well as the enables for the two on the lower left ( U3F1 and U3E1)AND!, when I press the power button, I get a beep sound as it’s powering up, and the shuts down right away. So it seems my problem is not what I thought after all, lol.Also that strange 3.3v issue seems random. It dropped back to .8v again and then back to 3.3.There is clearly something wrong with that section. But while it is working and the board powers up, I see some power supplies spike for a second and then the whole unit powers down.When I power up, I see no increase in current draw but 20ma, so I do t think I have a short. I wish I did, it might make this easier to hunt down.So clearly something is not seeing the correct voltage and it’s shutting back down.The main 12v supply for the APU doesn’t even hiccup at power up, so either that is a delayed start after the rest of the board chimes in as ok, or my issue is over there.One mosfet ( Q9D1 ) goes low on the gate when powerup.I see a spike on its output for a brief time. I’m going to try and track that down and see where it goes.It doesn’t seem to be tied into the three groups of fets for the APU supply, but I suspect maybe it enables them some how.

author: fzabkar
author_rank: Super Contributor
timestamp: November 29, 2019, 06:13:50 pm
content: U3D6 appears to be marked as "GEH", in which case it is in my BOM.

author: LiftedTrace
author_rank: Regular Contributor
timestamp: November 29, 2019, 10:25:02 pm
content: QuoteSorry, I missed that. Thanks.QuoteI no longer have that xbox. The only other one I have is my own working one and I am still on the fence for opening it up or not.QuoteI don't know how the two are tied together, the enable of U4C2 and the output of U3D6, but there is a shady looking cap on the back side of U4C2 (the 3.3V chip) that is connected to its enable pin, and I was pretty sure last I checked it, it measured short to ground. Maybe that cap is intermittent problem for why the 3.3v is sporadic. And every time the 3.3v chips gets a good enable, the output of U3D6 is also good.There are still some test points that do not turn on. I am trying to track down where Q9D1 goes off to. That closes when it powers up and then the system shuts down. I am thinking maybe the power from that is not getting to its intended destination. That's my theory anyways. I follow it into the enables of the three small chips U9D2, U9E1, U9E2. Those I suspect control the power for the 12v for the APU and I do not even see a blip of turn on when the box is powered on. It might also be nothing.Here is a higher res stitched together photo with more readable text. :https://www.dropbox.com/s/k1f7ol4rekuwrwq/XBOX%20Front.jpg?dl=0Seems my browser wont open that file, probably to large. Might have to be downloaded.EDIT 1:So I located what controls U9D2, U9E1, and U9E2. Its the larger chip NCP4205 (U9C2 ). Its coming from pin 28 on that chip. I looked thru google results for any type of datasheet but cannot seem to locate anything and I didnt see it on you BOM. I was hoping to back track thru and find out whats going on, but without a description of those pins, I have no clue if its working as intended.

author: fzabkar
author_rank: Super Contributor
timestamp: November 30, 2019, 01:08:42 am
content: Quote from: LiftedTrace on November 29, 2019, 10:25:02 pmIs it possible that the NCP4205's enable output is actually an enable input? That is, is the NCP4205 also being controlled from some other chip?FWIW, here are datasheets for chips with a similar part number:NCP4200, ON Semiconductor, Programmable Multi-Phase Synchronous Buck Converter with I2C Interface, 8-bit VID DAC, 4 x PWM, Vin = 5V, QFN-40:https://www.onsemi.com/pub/Collateral/NCP4200-D.PDFNCP4201, ON Semiconductor, Programmable Multi-Phase Synchronous Buck Converter with PMBus, 8-bit VID DAC, 4 x PWM, Vcc = 5V, QFN-40:https://www.onsemi.com/pub/Collateral/NCP4201-D.PDFIn fact, if there is a capacitor between the enable pin and ground, then this would suggest that the enable is configured like a simple RC power-on reset.Code:V+ --- R --+--> Enable||--- C---|_|_=

author: fzabkar
author_rank: Super Contributor
timestamp: November 30, 2019, 06:46:45 am
content: Just for completeness, could you identify the markings of these 5 chips on the back of the PCB?U5N1 is associated with L6B1 on the top side, so it must be a stepdown buck regulator.U1P1 DFN-10Q1P2 SOT23-3U5N1 SOT23-5Q6R2 SOT23-3U6U1 SOIC-8 audio amp

author: fzabkar
author_rank: Super Contributor
timestamp: November 30, 2019, 09:17:45 pm
content: These would be my power supply test points:

author: fzabkar
author_rank: Super Contributor
timestamp: November 30, 2019, 09:20:35 pm
content: More test points ...

author: LiftedTrace
author_rank: Regular Contributor
timestamp: December 01, 2019, 06:25:17 pm
content: I really appreciate the time your taking to help me figure this out. Its a learning experience for me. I think I took care of the strange 3.3V output with the flaky enable. I replaced a cap and a resistor that were connected to the enable of U4C2. I cannot believe how challenging it is to replace these little buggers. Now that this enable has a good voltage to it, the 3.3v is working well. That being said, here is a list of all the test points you were asking for in them pics.The ones that state "only after power on" go right back to zero after the unit shuts down.TP4D1 = 3.29TP4D2 = 5TP4D4 = 1.83TP4D5 = 1.135TP4E1 = 1.11 (Only after power on)TP4F1 = 1.81 (Only after power on)TP4F2 = 1.83TP5F1 = 0 (Even after power on)TP5D1 = .6 (Only after power on)TP5D3 (v_fuse) = 0TP6F1 = 0 (Even after power on)TP8B1 = 12TP9D1 = .72 (Only after power on)TP9D2 = 0 (Even after power on)TP9F1 = 0 (Even after power on)RT3F1 = 5RT6B1/2 = Both 5VL6B1 (Vout) = 12VC9C5 (Vout) = 12VU5D2 (pin 2) = 3.29C5D4 = 1.84 (Only after power on)U3D6 (Pin 5) = 1.83The Chips on the back - IdentificationU1P1 1206 Q1P2 KFD U5N2 C08F Q6R2 KFD U6U1 8104SY187K 829 (C has a line over it) 829 1814ADRG (08F have lines under them) 28053010QuoteI am not sure. I know the data sheets for NCP4200/NCP42001 do not have the same number of pins, but they list the enable pins as pin 6.The pin that is connected to the three chips, U9D2, U9E1, U9E2, is 28. Pin 28 on UC92 is connected to pin 3 on all three of them chips thru a resistor.UC92 (Pin 28) -----------|-----(R)------U9D2 (pin 3)||-----(R) -----U9E1 (Pin 3)||-----(R)-----U9E2 (Pin 3)If NCP4205 is similar, then it looks like the enables are all tied together to the bigger chips PWM(one of them) outputs, or the SW(one of them) output. Thats assuming they are similar enough where the PWM and SW are on the same sides.Also, Pin 2 on U9D2 is connected to pin 27 of UC92.So one thing I noticed when checking these test points is two of them were low when it powered up.TP5D1 = .6 (Only after power on) It should be 3.3vTP9D1 = .72 (Only after power on) Not sure what this should be.TP9D1 seems to be coming from the power supply in the lower right corner (U9F1). This seems to start up a bit but I dont know what it should be at. The test point is labeled MEMIO, so maybe it should be this low?EDIT 1:Forgive the hackery and ugliness of my skills. This:https://www.dropbox.com/s/ilu2rzqa8l6ucx5/XBOX%20Back.jpg?dl=0is a photo of the back of the board. I seen this on the other xbox I had, the way the caps look. Like one side is missing the solder covered connection. Located on the left side in section "S" and "T" and "U"."U" seems to be missing a Cap all together, and the one that is present seems to be missing its right solder connection. I remember this from the other board. I wonder how much of this is from water damage and how much is how it was from the factory.The section in U1 also has some ugly looking caps, and when I tried to touch up the test points in that area, the board masking peeled off.I wonder if there are traces inside the board that have eroded from the water damage. Is that even possible?

author: fzabkar
author_rank: Super Contributor
timestamp: December 01, 2019, 10:32:44 pm
content: I would think that MEMIO is the supply rail for the SDRAM chips, in which case it should be 1.5V (according to the data).I would also measure the resistances between ground and each of the suspect test points.ISTM that the SoC (U4D2) is powered from the primary standby supplies (V_3P3STBY, 1P8STBY, 1P1STBY). When it senses the power-on switch, it enables several other supplies, and these in turn enable the supplies for the SDRAM, CPU, GPU, and NorthBridge. I suspect that one of these supplies, or its load, has a problem, and that this problem causes the power-up sequence to terminate.I would concentrate on those supplies that never come up to spec, even briefly (the last 7 in the list). Check their inputs, outputs, enables, and load resistances.Code:TP4D2 = 5P0 5RT6B1/2 = rear USB Both 5VRT3F1 = front USB 5L6B1 = 12VC9C5 = 12VTP8B1 = V_12P0 12TP4F2 = V_BAT 1.83TP4D1 = V_3P3STBY 3.29TP4D4 = 1P8STBY 1.83TP4D5 = 1P1STBY 1.135U5D2 (pin 2) = 3.29U3D6 (Pin 5) = 1.83TP4E1 = SB1P1 1.11 (Only after power on)TP4F1 = SB1P8 1.81 (Only after power on)C5D4 = V_SOC1P8 1.84 (Only after power on)TP5D1 = V_3P3 0.6 (Only after power on) should be 3.3V (from U5D4 ?)TP9D1 = MEMIO 0.72 (Only after power on) should be 1.5V from TPS51916 et alTP5D3 = V_FUSE 0 from pin 5 of U5D3 LDO reg (AP2127)TP5F1 = SOCPHY 0 (Even after power on) from U5F5 switcherTP9D2 = GFXCORE 0 (Even after power on) from NCP4205 switcher et alTP9F1 = CPUCORE 0 (Even after power on) from NCP4205 switcher et alTP6F1 = NBCORE 0 (Even after power on) from TPS53819A switcher et al

author: fzabkar
author_rank: Super Contributor
timestamp: December 01, 2019, 11:21:23 pm
content: I just reread one of your earlier posts and I'm sorry for my misleading reply. Of course the NCP4205 chip enables each of U9D2, U9E1, and U9E2. Those are the MOSFET gate drivers for the CPUCORE.Doh! (slaps forehead)

author: LiftedTrace
author_rank: Regular Contributor
timestamp: December 02, 2019, 12:23:37 am
content: QuoteOk, So the output doesn't even hiccup on power up. The Shutdown control pin 3 i see a tiny spike when power on. I cannot track down where that pin 3 is connected. Its resistance to ground is 10K. I am suspecting its not getting enough to turn on. I could supply it with a small amount, but I am reluctant to, not knowing what it needs or where its going, so I am going to not do that. There are two diodes right next to it. (D5D2), the cathode goes to 3.3V after power on, the anode goes to .06. If I am not mistaken, should this not be around .7?QuoteThe input has a steady 3.3V and the output has nothing. I probed the other pins and found no other voltages present before or after power on. I cannot locate the datasheet on this chip either so I dont really know what pin does what.QuoteThis is coming from the three groups of mosfets that are not coming up. The chip that controls them getting its enable from NCP4205.QuoteOk, so I may be getting closer to something.TP9D2 = GFXCORE & TP9F1 = CPUCORE seem to be tied together. I noticed something strange though.When I measure the resistance between TP9D2 = GFXCORE and the output of Q9D3(larger mosfet by large first coil), I get .3_Ohms.When I measure the resistance between TP9F1 = CPUCORE and the output of Q9E3(larger mosfet by large last coil), I get .3_Ohms.When I measure the resistance between TP9D2 = GFXCORE & TP9F1 = CPUCORE I get 10.4_Ohms.So I started measuring the resistance between each of the larger mosfets.1-2 = .32-3 = 10.41-3 = 10.41-G = 3.62-G = 3.43-G = 7.8I find it strange these are not all the same which makes me think the issue may be on this power supply.Maybe its fine? I do see a slight gap between the two top coils and the bottom coil. Maybe I am measuring the resistance thru the APU from the GFXCore and the CPUcoreQuoteThe Vdd goes to 12v on power up. The enable and output gets nothing on power up.QuoteInput is seeing 5V, Output spikes on power up, Enable Spikes a small amount on power up.After measuring all of these, the only one that seem odd to me is the one by the diodes (U5D3).Would it be normal for the voltage before the diode to be 3.3, and after be .03-.06?

author: fzabkar
author_rank: Super Contributor
timestamp: December 02, 2019, 12:56:39 am
content: ISTM that MOSFETS Q9D3 and Q9E1 supply the GPU core, while MOSFET Q9E3 supplies the CPU core. In fact you can see "CPUCORE" adjacent to capacitor C8E3, and "GFXCORE" between C8D1 and C8D2.The resistance that you are measuring "between the two cores" is actually the sum of the resistances from CPUCORE to Ground, and from Ground to GFXCORE, ie 7.8 + 3.5 = 11.3 ohms.

author: fzabkar
author_rank: Super Contributor
timestamp: December 02, 2019, 01:06:50 am
content: Quote from: LiftedTrace on December 02, 2019, 12:23:37 amI don't understand what you mean by "before and "after". The forward voltage drop would be limited to around 0.6V, while the reverse voltage rating could be 20V or more. A Schottky diode would have a lower Vf than a regular silicon rectifier.

author: LiftedTrace
author_rank: Regular Contributor
timestamp: December 02, 2019, 01:37:26 am
content: QuoteMy apologies. What I meant by "before" was the reading at the cathode and "after" was the reading at the anode.Would a schottky diode have a forward voltage drop under .1v?Maybe the only was I can check is to remove it and check out of circuit?QuoteI see that now. By the way, what does "ISTM" mean?https://www.diodes.com/assets/Datasheets/ds30308.pdfI believe is the schottky (D5D1 & D5D2). This lists the forward voltage as .3 ish.Am i on the right track thinking this should be higher than .03-.06?

author: fzabkar
author_rank: Super Contributor
timestamp: December 02, 2019, 01:51:55 am
content: ISTM - it seems to meA forward voltage drop of 0.1V is quite possible for a Schottky diode if the current is very low.FWIW, I checked the V_EFUSE references in the Xbox 360 circuits. In that particular design the CPU generates a VREG_EFUSE_EN signal which enables an LDO regulator. This regulator generates a V_EFUSE supply from the V_5P0 supply, and V_EFUSE then powers one section of the CPU's internal logic. I have no idea what V_EFUSE does.The V_3P3 supply in the Xbox 360 is generated by an LDO regulator, and this regulator is controlled via a VREG_3P3_EN signal from the SouthBridge.Did you check the MEMIO regulator? Its output should be 1.5V.

author: LiftedTrace
author_rank: Regular Contributor
timestamp: December 02, 2019, 02:08:28 am
content: At this point, it seems I have quite a few power supplies not turning on because they are lacking their enables for some reason. Either they have no enable at all, or the enable never stays on. Other than the really low voltage on the schottky, I can not imagine what it might be. I could take that off and measure it just to see I suppose, but with a reverse break down voltage of 30v, I find it hard to believe this is the problem seen as its only seeing 3-4V.I am trying to stay away from opening my xbox up, but I am thinking I may need a working one as a reference.....unless you may have any other options to check?EDIT:QuoteI did, it seems to be controlled by U9F1. Pin 13 (SW) spikes to about .7, same as MEMIO test point.Pin 16&17 shoot up to 2.5 for a split second. I believe these are the enables of the chip.http://www.ti.com/lit/ds/symlink/tps51916.pdf(Page 17, State S0). Pin 16&17 are tied together, both are either Low (State S4/S5) or High (State S0).So this chip too is not getting its enable held high.Something else is triggering this whole thing to shut back down.

author: fzabkar
author_rank: Super Contributor
timestamp: December 02, 2019, 02:18:14 am
content: Quote from: LiftedTrace on December 02, 2019, 02:08:28 amMEMIO regulator?You could check the voltages on U5D4.Here is my guess:pin #1 - enable from southbridgepin #2 - ground or 5V inputpin #3 - 5V input or groundpin #4 - V_3P3 outputpin #5 - not connected ?pin #6 - feedback divider

author: LiftedTrace
author_rank: Regular Contributor
timestamp: December 02, 2019, 02:33:46 am
content: Ok, well I looked a little deeper. The pins on the chip itself (16&17) are not connected, but a resistance check between them shows .3_ohms.Right behind it, is the ugliness I was talking about in the high res image of the back of the board.The fact that pin 17 is connected to this ugly looking cap makes me wonder.

author: LiftedTrace
author_rank: Regular Contributor
timestamp: December 02, 2019, 02:40:08 am
content: QuoteCorrect. This chip has 5V on it. The enable spikes up and back down, and Pins 4&6 seems to be connected in a feed back configuration. Pin 5 seems t0 be NC

author: fzabkar
author_rank: Super Contributor
timestamp: December 02, 2019, 02:51:40 am
content: It seems odd that you found and replaced one genuine shorted component, but now you have another problem. I'm wondering whether you introduced a second fault.My other question is, can the CPU/GPU run without a heatsink? Does it throttle itself if it gets too hot?

author: LiftedTrace
author_rank: Regular Contributor
timestamp: December 02, 2019, 03:02:14 am
content: QuoteIt is very strange, I agree.As for the heatsink issue, I would say no, it cannot be run without a heatsink, but its not even getting powered up to generate any heat.When I press the power button, I go from 30ma to 40ma current draw and back down. It it is only powered up for 1 second top, maybe less.The system shuts down almost instantly.

author: fzabkar
author_rank: Super Contributor
timestamp: December 02, 2019, 03:04:05 am
content: Quote from: LiftedTrace on December 02, 2019, 02:33:46 amI think we are both going blind. Pins 16 and 17 of U9F1 are connected on the top side of the PCB.

author: LiftedTrace
author_rank: Regular Contributor
timestamp: December 02, 2019, 03:06:46 am
content: QuotehahahahahI must be tired, lol.I was mistaking pins 11&12 for 16&17 DOH!!!Ok, then in that case, on the photo i uploaded, pin 12 is the one thats connected to that funky looking cap.So 16&17 do still only get a short burst of voltage and turn off again. What troubles me is when I measured between 11&12, thinking they were 16&17, I did get .3 ohms.Thats .3 ohms between pins 11&12. The data sheet lists them as V5IN and DRVL.I dont think these guys should be measuring a short between them do you?Unless they are connected internally? One being an input and another an output?

author: fzabkar
author_rank: Super Contributor
timestamp: December 02, 2019, 03:20:08 am
content: Quote from: LiftedTrace on December 02, 2019, 03:06:46 amThey should not be connected, either externally or internally. Something is wrong. Is it possible that you shorted the two pins while you were testing?Otherwise, it could be that Q9F1 and Q9F2 are damaged.

author: LiftedTrace
author_rank: Regular Contributor
timestamp: December 02, 2019, 03:32:16 am
content: QuoteIts very possible I shorted them testing. The pins are very close together and I do not have a microscope. Only a small eye loop.Measuring across Q9F1/2 doesnt show a short though.EDIT:OK, I think pin 11&12 were shorted. one of the pin solder was mushed. I fixed it. Same result though.Pin 12 has constant 5V. now. Pin 11 spikes to about 3.2 then off again, and 16&17 spike up and down.So it seems this one may me working too, but not getting its enable to stay on.

author: fzabkar
author_rank: Super Contributor
timestamp: December 02, 2019, 04:32:37 am
content: I'm stumped. Sorry. :-(

author: LiftedTrace
author_rank: Regular Contributor
timestamp: December 02, 2019, 04:42:14 am
content: I guess that means it’s time to open my Xbox for comparison

author: fzabkar
author_rank: Super Contributor
timestamp: December 02, 2019, 04:49:08 am
content: I'm just parking my rough notes here. Maybe someone will be able to fill in the missing info.X861949-007, Microsoft XBOX ONE ASIC, I/O Controller Hub, southbridge:X949211-001, AMD, CPU/GPU:USB 2.0 filter (U3F2), markings KR + 82 (cursive, 82 = date code?), DFN-6, probably equivalent to ...PESD5V0U5BF / PESD5V0U5BV, NXP, Ultra low capacitance bidirectional ﬁvefold ESD protection array, 1.9pF, 5V reverse standoff, marking B2 / G7, SOT886 / SOT666:https://assets.nexperia.com/documents/data-sheet/PESD5V0U5BF_PESD5V0U5BV.pdfTHGBMFG6C1LBAIL, Toshiba, eMMC NAND Flash, 8GB, 1 x 64Gbit, 3.3V / 1.8V, BGA-153:https://www.es.co.th/Schemetic/PDF/THGBMFG6C1LBAIL.PDFfrom Xbox One S teardown:https://de.ifixit.com/Teardown/Xbox+One+S+Teardown/65572RT8111HM, Realtek, Ethernet controller, single port, Gigabit LAN, PCI Express, QFN-32:Similar chips with higher pin count?https://www.recomb-omsk.ru/published/SC/html/scripts/doc/A01-RTL8111EVL-F(RTL8111E-VL-CG_Datasheet_1%201.pdf(RTL8111E, QFN-48)bothhand.info/pdf/spec-8111b%28140%29.pdf(RTL8111B-GR, QFN-48)Diodes Inc ?, Schottky rectifier, marking 5X, SOD123NTMFS4C50NT3G / NTMFS4C50NT1G, ON Semiconductor, MOSFET N-CH, 30V, 46A, marking 4C50, SO8FL:https://www.digikey.com/product-detail/en/on-semiconductor/NTMFS4C50NT3G/NTMFS4C50NT3G-ND/4848828https://www.digikey.com/product-detail/en/on-semiconductor/NTMFS4C50NT1G/NTMFS4C50NT1G-ND/4848827U7B2, marking PWD + yww, STMicroelectronics, BGA, EEPROM, HDMI EDID + CECU8B1, marking PXD + yww, STMicroelectronics, BGA, EEPROM, HDMI EDID + CECphoto of U6U1, marking 8104SY1 + 1612 + 26082460 -> compared with 8104SY1 + 1814 + 28053010https://www.elektroda.pl/rtvforum/topic3387811.html#gallery-4U5F5, markings 3A + 5F + C02, DFN-10, step-down converter (3A + FF + Q3W markings in Xbox One teardown)Parts ID:https://cdn.ihs.com/www/blog/consoleunder.pnghttps://www.elektroda.pl/rtvforum/topic3387811.htmlQuoteMP2161GJ, Monolithic Power, Synchronous Step Down Switcher, 2A, 2.5V - 6Vin, 1.5MHz, 17uA IQ, marking AEBy, TSOT23-8:https://www.monolithicpower.com/en/documentview/productdocument/index/version/2/document_type/Datasheet/lang/en/sku/MP2161/document_id/450

author: LiftedTrace
author_rank: Regular Contributor
timestamp: December 06, 2019, 02:53:34 pm
content: So I have a little more info but I don’t know what it means.My gut tells me there is something wrong in the area of U5D2 and U5D3.I took my Xbox apart for reference and what I found was strange at the two diodes labeled D5D1 & D5D2D5D2, Ohms reading, positive on anode, negative on cathode = 300D5D2, Ohms reading, negative on anode, positive on cathode = 10kishD5D1, Ohms reading, positive on anode, negative on cathode = 300D5D1, Ohms reading, negative on anode, positive on cathode = 10kishThese are for the good working Xbox.What I get for the broken one is.D5D2, Ohms reading, positive on anode, negative on cathode = 260D5D2, Ohms reading, negative on anode, positive on cathode = (Fuke 115 meter “flashes” OL)Manually setting range I get a value around 2.5kIt seems to mess up the auto range (confusing)Same result for D5D1Do you know what would cause the meters auto detect to freak out and flash OL. It was not steady like a normal open, but flashed. I don’t know what means. Best I could guess is a cap somewhere was charging and discharging quickly?Anyways, it’s not normal to the working box, so I think what ever is causing this issue and the low ohms readings on across these diodes might be a step in the right direction.EDIT 1:Well, I have managed to fix the thing. While waiting for a response here from my last post, I decided to go thru the back side of the board and replace the nasty looking caps, and wouldn't you know it, the thing booted up, lol.I guess thats a lesson learned that something on the opposite side of the board can effect another area which seems totally unrelated.But its up and workingFeels good to fix it.

author: fzabkar
author_rank: Super Contributor
timestamp: December 08, 2019, 03:38:34 am
content: Congratulations!

author: ijaved
author_rank: Newbie
timestamp: December 10, 2019, 08:44:37 pm
content: Wow very encouraging post. I have one dead xbox one s sitting with me which I have to fix. I will definitely use this post to get pointers.Do you have picture of the back on which area the cap went bad?

author: fzabkar
author_rank: Super Contributor
timestamp: December 11, 2019, 01:54:11 am
content: ICBW, but I think the OP was referring to the capacitors in the GFXcore and CPUcore sections. I thought that the measured resistance of 3 ohms seemed on the low side, but then the GPU and CPU draw tens of amps when running, so I dismissed it. In any case it would be interesting to know how the capacitors measured out of circuit. It would also help to know the normal resistance of the GFXcore and CPUcore loads on a working board.

author: LiftedTrace
author_rank: Regular Contributor
timestamp: December 11, 2019, 03:53:56 am
content: Yeah, so on page one there is one of the posts has a pic of the back of the board. I thought I posted a higher res pic but can’t find the link.Basically, these are what I replaced.C1R10 / 11C1T1 / 2C1U2C1U1( Already gone on a known good working Xbox, left it missing)C1U3 / 4I also had a strange issue with the RC section for the 3.3v area.I replacedR6P16C6P13The board is laid out in a nice grid format to locate these components as stated in one of the earlier posts.These are all on the bottom of the board where the water damage was.As for the caps in the GFxcore and CPU core sections, the large cans, I never touched them. It was only the small ceramic caps on the bottom I replaced.Sadly I was so excited to see it draw a few amps and stay on and jumped the gun and put it all back together and started the updates.I wish I would have taken measurements from it when I had the caps and stuff off not causing issues to see what normal was. I wasn’t ready to start taking my known working one apartAlso, being water damage, it seems to have completely eaten away the solder on the caps and the board leaving a ugly connection if any exists any more.A few of them I had to scrape the nasty away and then scrape some of the trace cover away to expose good copper so I could solder to that. You might have to get creative depending on how corroded they might be.You can remove one of the caps off the top of the board in that section for the 8 I replaced. They are all in parallel. Two on top and two on the bottom, except for that one that seems to be deliberately missing one on the bottom. I forget the value, but I found donors from a old laptop mother board power supply section.The one I got of eBay had the same section messed up and they looked the same. Maybe the water pools up in that corner.Also the one I got from eBay had such bad damage it was beyond my repair. When looking closely at the ram chips at just the right angle(and my tongue also at just the right angle) I was able to see water damage under the ram chips. It was at the point I called it quits and resold it on eBay. I don’t have the means to remove large chips like that.Best of luck.Anything I can do to help, just post.Also, as a reference, the one I repaired, just beeped on startup.I had no fan or anything. It did a three rising tone beep and immediately shut off.My working Xbox was drawing only 9ma on standby where the broken was drawing around 40ma.Hope this helps.

author: fzabkar
author_rank: Super Contributor
timestamp: December 11, 2019, 10:33:41 pm
content: Quote from: ijaved on December 10, 2019, 08:44:37 pmWould you mind filling in the missing voltages?Also, if any of your ICs differ from the OP's, would you mind posting their markings so that we can identify them and update the BOM?

author: Eli
author_rank: Newbie
timestamp: December 30, 2020, 02:34:47 pm
content: Good day my xbox one s won't turn onupon searching the net i found this thread, i did test all the test pointand my 5v TP4D2 test point is deadshort to ground also the 3.3v testpoint doesn't have a voltagebut is not short, hope someone could answerthanks..

author: LiftedTrace
author_rank: Regular Contributor
timestamp: December 30, 2020, 03:25:50 pm
content: Did it just stop working one day, or did you spill something on it, etc. I came across a non working xbox that had a short inside the board at a connector. I had to dig the trace out until there was no more short and then run a wire to where it went. Still never got it working on that xbox. My point is the show is not always as easy as a component shorted.I am no expert and I do what I have seen others do on YT with finding shorts, using a current limit power supply and feel around for whats getting hot. I don't know of any other way to find them. I know some here will say that is not a good method of finding shorts too, so I leave it up to you to decide. The way I seen it, it wasn't working, so I had no worries of breaking it.

author: seintohackers
author_rank: Newbie
timestamp: April 28, 2022, 08:10:24 pm
content: Hi!!somebody have any info about U5D4 ic, datasheet or something to replace whit similar component pleasepin 1.- 5v Enable(when push poweron button)pin 2.- groundpin 3.- 5v IN (from 5v standby voltage)pin 4.- 3.3v OUT (Testpoint TP5D1)pin 5.- No Conectionpin 6.- 3.3v feedback to U5D4va6xfva7bava7nethanks!

author: seintohackers
author_rank: Newbie
timestamp: April 28, 2022, 08:35:55 pm
content: in this zone Dcheck diodes D3D1, D3D2and transistors U3D6 Q3D5IC U4D4Testpoint TP4D5 1.1v standby and TP4D4 1.8v standbythis zone send the voltage to U4C2 to enable that IC and create the 3.3v output Testpoint TP4D1Your u4c2 needs to have Vin and VEnable to create V output

author: fzabkar
author_rank: Super Contributor
timestamp: April 28, 2022, 08:43:37 pm
content: U5D4 appears to be an adjustable LDO regulator. Could you tell us the voltage at the feedback pin, ie 0.6V, 0.8V?"VA" appears to be the part code, while "6" and "7" appear to be the year of manufacture.

author: seintohackers
author_rank: Newbie
timestamp: April 28, 2022, 10:08:11 pm
content: yes is LDO regulator, the feedback pin drops 0.8v because in the output pin drops 0.8, is not short to groundthe LDO is just damage i test in diode mode and i have normal voltage drop signal 0.4mV and i cant find the datasheet to replace, thanks

author: damanloox
author_rank: Contributor
timestamp: June 24, 2022, 08:49:40 pm
content: had similar issue (ie. dead board - no sign of life, 12v OK everywhere, 5V OK everywhere and no 3v)... Spent a few hours trying to find the problem and almost gave up but decided to replace IC U4D4 as a last attempt to save the board and... success. 3.3v suddenly appeared and the console works without any issues.

author: kszyh0
author_rank: Newbie
timestamp: August 17, 2022, 09:30:11 am
content: Has anybody found the U5D4 component. Struggling to replace this one. I went through ST offered LDOs as well as most of ONSEMI but none of them seems to be matching the pinout of this chip.Any hint highly appreciated.Is pin 6 really a PG pin (Power good, feedback) or ADJ pin (Vout setting)?

author: seintohackers
author_rank: Newbie
timestamp: September 09, 2022, 06:26:48 pm
content: The brand is Foster model FST6472pin 1.- 5v Enable(when push poweron button)pin 2.- groundpin 3.- 5v IN (from 5v standby voltage)pin 4.- 3.3v OUT (Testpoint TP5D1)pin 5.- No Conectionpin 6.- 3.3v feedback to U5D4

author: fzabkar
author_rank: Super Contributor
timestamp: September 11, 2022, 02:24:43 am
content: Quote from: seintohackers on September 09, 2022, 06:26:48 pmIt looks like the feedback reference voltage is indeed 0.8V. It surprises me that MS would use a chip that doesn't appear in Internet searches. :-?

author: seintohackers
author_rank: Newbie
timestamp: September 11, 2022, 01:34:47 pm
content: its a japanese brand, i contact them, and they send me the datasheet

author: gamalot
author_rank: Super Contributor
timestamp: September 11, 2022, 02:43:09 pm
content: Quote from: seintohackers on September 11, 2022, 01:34:47 pmKind of weird, the Japanese gave you a Chinese version of the datasheet?

author: seintohackers
author_rank: Newbie
timestamp: September 16, 2022, 08:47:53 pm
content: the lenguage of the datasheet is irrelevant, schematic is clear to read and understand

author: fzabkar
author_rank: Super Contributor
timestamp: September 16, 2022, 10:48:42 pm
content: Quote from: fzabkar on September 11, 2022, 02:24:43 amIf you take either the 5-pin or 6-pin version of this chip and turn it on its back, the pinout matches ...https://www.micros.com.pl/mediaserver/ST6212-adjm5r_0001.pdfThe FB voltage is also 0.8V.I suspect that there may be more popular LDO regulators with the same mirrored pinout. This may be an option if you can't match the original pinout and FB voltage.Another mirrored pinout (fixed 3.3V 300mA regulator):https://www.ti.com/lit/ds/symlink/tps7a20.pdfMirrored pinout, 150mA, 0.8V FB, adjustable:https://www.st.com/resource/en/datasheet/ldcl015.pdf

author: Maxwell55
author_rank: Contributor
timestamp: March 11, 2024, 12:21:14 am
content: I just found this thread and followed the troubleshooting steps. I have all my voltages & standby voltages as well. the only voltages missing are the MEMIO, GFXCORE & CPU CORE. NO shorts found, the only IC that looks suspicious is U9F1 (TPS51916), All caps checked, all mosfets checked. Does anyone know what type of voltage outputs I'm supposed to get out of IC U9F1? Any tests I can do to check if its functional? Any help appreciated. Thanks

author: LiftedTrace
author_rank: Regular Contributor
timestamp: March 11, 2024, 02:10:47 am
content: Its been a while since I have had mine open. I forgot about this thread.I can open mine up and take a few measurements for ya on IC U9F1 when its powered up and working.Ill post back as soon as I can with the info. Might be a few days.

author: LiftedTrace
author_rank: Regular Contributor
timestamp: March 11, 2024, 03:31:19 am
content: U9F1Powered on and off for each test as my GPU started to get hot when plugged in.Everything is disconnected ( HD, CD, FAN & Heat Sink, WIFI card) only have front card plugged in for power button....which it seems I didnt need as when I plugged it in, that chip came to life.Measured each pin to ground.With board facing in the direction of the USB ports and HDMI and stuff towards the back, power button towards you. I dont know which pin is 1, I opted for the pin on the bottom by the dot on the chip and went CCW around it. This is what I found.Pin:1: .75V2: 1.5V3: .75V4: 0V5: .755V6: 1.8V7: 0V8: 1.51V9: 1.51V10: 011: 1V (After about 5 seconds....was fluctuating above and below 1V, then stabilized)12: 5V13: 1.52V14: 1.65V15: 6.55V16 & 17 : 3.26 (Pins Tied together )18: 2.44V19: 0V20: 5VHope this helps.Ill leave it apart if you need me to take any other quick measurements.

author: Maxwell55
author_rank: Contributor
timestamp: March 11, 2024, 06:28:37 am
content: Thank you so much, I read and reviewed this thread religiously after the Xbox went dead. The only dust was found around the bottom right corner near U9F1, this unit had no water damage, I inspected both sides of the board for damage and checked as many components as I possibly could and like I mentioned all other voltages are present except the ones I listed. I will get to check your findings hopefully tomorrow and report, I don't have many smd tools to work with so it will be a challenge, unless it's a cap or something easily removable, can you please verify if there should be continuity between TP9D2 & TP9F1? Wish me luck..

author: LiftedTrace
author_rank: Regular Contributor
timestamp: March 12, 2024, 01:55:52 am
content: I measure 2.5 ohms between them two points.

author: LiftedTrace
author_rank: Regular Contributor
timestamp: March 12, 2024, 02:40:27 am
content: For what's it's worth, I get 1.73 ohms from TP9F1 to ground,And .86 ohms from TP9D2 to ground.

author: Jason Henry
author_rank: Contributor
timestamp: March 12, 2024, 08:55:14 am
content: It's possible the unidentified chip is causing the issue with the 3.3V output. Try checking for any visible damage or consider replacing the chip if you can identify it. Good luck with the Xbox repair!

author: Maxwell55
author_rank: Contributor
timestamp: March 14, 2024, 12:24:07 am
content: Hi, sorry for delay I was tied up with other stuff. Ok so I checked the resistance on those pointsI got 2.9 Ohms, 1.9 Ohms and 1.1 Ohms respectively from those test points. I will get on to checking the U9F1, hoping not to short any pins.I don't see any damage, corrosion, anywhere or any other visible suspects from both sides of the boardForgot to mention I do have 3.3V at TP4D1, not sure where its bogging downEdit: Impossible to measure any voltages on U9F1 as the board cuts out 1 sec after I turn it on

author: LiftedTrace
author_rank: Regular Contributor
timestamp: March 14, 2024, 01:10:14 am
content: Are you sure the power supply is working as it should?

author: Maxwell55
author_rank: Contributor
timestamp: March 14, 2024, 02:29:57 am
content: Yes, it's definitely working and no shorts between the rails.Measured voltages on PSU = 11.99V unloadedthen;TP881 = 11.98VTP4D2 = 5.0VTP4D1 = 3.3VTP4D4 = 1.8vTP4D5 = 1.1vwhen the pwr button is pressed, the white led comes on, it beeps (chirps) once and goes off.When I opened it up, I only found dust on / near U9F1 (bottom right of the board), cleaned it off but found nothing else on either front or backside of the boardWHile checkingthe mosfets, I then noticed no voltage to MEMIO, GFXCORE & CPUCORE, all mosfets were checked and none were found bad

author: LiftedTrace
author_rank: Regular Contributor
timestamp: March 14, 2024, 02:40:43 am
content: So the issue i had sounds similar but mine was caused my water damage and it took out some caps on the back side of the board.For example, C1T1 and C1T2 and all similar on this side and the other that are connected to the main chips power supply.I ended up finding some off a donor board and just replaced them all.Honestly dont even know what value they were but they were similar insize lol. I know, not ideal, but it worked.Perhaps you have a fault where there is one or more caps open instead of short.

author: Maxwell55
author_rank: Contributor
timestamp: March 14, 2024, 05:25:56 am
content: multiple blow caps has crossed my mind, as I am unable to find any shorts. The only other way would be to inject voltage but I don't have a thermal camera to spot any heat pointsI will continue to check the backside but I'd sure like to know where the rail comes from to see if I can follow it along to where its not reaching the mosfets and ram area

author: Maxwell55
author_rank: Contributor
timestamp: April 08, 2024, 04:19:13 am
content: Still unable to find the problems, I've checked all usual suspects, caps, fets..etcI don't where else to lookWould you be able to measure the U4C1 outputs voltages on pins, 1,2,3 & 4 ?

author: LiftedTrace
author_rank: Regular Contributor
timestamp: April 12, 2024, 05:46:35 pm
content: QuoteSorry for the delay, I missed this post in my email.Here are the voltages for that chip.(Powered on means it beeped and fan started spinning.)1: 0V Powered Off, 11.8V Powered On2: 0V3: 11.9 Powered Off & On4: 0V5: 0V6: 1.58 Powered Off & On7: 0V Powered Off, 3.27V Powered On8: 1.58 Powered Off & On9: 3.26 Powered Off & On10: 1.58 Powered Off & On11: 0V Powered Off, 3.26 Powered On12: 0V13: 0V14: 11.8 Powered Off & On.

author: Maxwell55
author_rank: Contributor
timestamp: April 20, 2024, 04:50:20 am
content: Thanks, I checked and compared the voltages at LM339 which supplies the gated voltages and this is what I got.Note: I did not have the HDD or optical drive installed or anything else.1: 0v off & on2: 0v off & on3: 11.96 off & on4: 0v off & on5: 0v off & on6: 1.58v off & on7: 0v off & on8: 1.58v off / 1.58 on9: 0v off / 0.9v on10: 1.58v off / 1.58v on11: 0v off & on12: 0v off & on13: 0v off / 29mv on14: 0v off / ~3v onI suspect this IC could be fried,but I'm not 100% sure yet, I will check the continuity between the gatesEdit: What is strange on the LM339 is pin9 input voltage, I'm not getting the 3.26V that supplies the FETs for the Gated voltages, Can you take a reading on R9D15 whenever you can? Thanks