820-02100/02098 LCD Backlight Controller IC UP800..

[Timp74]

Hi All.

Does anyone know if Macbooks will power on without their display backlight controller ICs? Explicitly I have an a2485(very similar to a2442) that has the UP800 IC broken/missing. On attaching a USB PD charger it stays at 5v ~1A for 20 seconds and then resets and repeats the cycle.

The history is that the machine was water damaged to IC UP800. A Renesas 209100b1 Buck Boost controller. The machine still worked, but without the display backlight coming on. UP800 wasn't generating any switching signals to the four driver mosfets. I removed UP800 and check the PCB and surrounding components. Everything tested okay. I cleaned and reballed the IC and put it back on the board. On connecting a USB charger, the machine started power cycling as initially mentioned. I removed UP800 again, but it still power cycles.

When the USB charger is connected, the 3v8 AON rail is good and stable for the 20 seconds the machine is on. The PP5V_S2_MAIN rail switches on and off at about 1Hz, as do the 1v8 and 1v2 rails. It's like the machine is trying to bring up the power rails but fails and resets. I fear I may have messed up the reball and sent power down the I2C or EN lines to the SOC. Although I was quite careful and checked for shorts after the reball. Also, looking at the pin layout of UP800 it's hard to see how any of the power rails could short to the SOC lines. With UP800 removed, there is a weird(non-binary) pulse coming from the SOC on the BL_PWR_EN line and SPMI_DISP_BKLT_DATA steps up to 1.2v, both synchronised with PP5V_S2_MAIN's 1Hz. Nothing on SPMI_DISP_BKLT_CLK. There are no pull-up resistor on the schematic which is weird assuming it's i2c.

I'm currently looking at buying a new UP800 from AliExpress but they are extortionately expensive, so it would be good to work out if the current problem with the machine is just because of the missing backlight controller, or if I've damaged something else and it should still power on without UP800. Any help would be greatly appreciated whether it's about the backlight controller or similar failure modes on M1 Macbooks.

Thanks.

[Timp74]

Re: 820-02100/02098 LCD Backlight Controller IC UP800..

Sorry. It's actually drawing about 1 watt at 5v, not 1 amp. I have a new USB DP meter that I should learn to read... It also power cycles after about 25 seconds, not 20.

[yra98621]

Re: 820-02100/02098 LCD Backlight Controller IC UP800..

Hi, I have an A2442 with a motherboard problem 820-02098, at first it was damaged by water, I was able to get it fixed but I did not completely, i get error 21 in apple configurator 2 and in DFU mode, I thought that the problem could be NAND it was visually browna little bit, up to here I was able to turn on the mac but the apple logo came out and immediately after restore image , I tried to remove first Renesas 209100b1 and reball it, just to try, maybe it works again, and after removed bad NAND and now It continue boot loop and I don't understand why , visually I checked everything more times and I have no short circuit but it keeps going out so it doesn't even want to turn on,



I attach the link with Google drive with video.


https://drive.google.com/drive/u/0/f...zxndf_CeP3MPNU

[yra98621]

Re: 820-02100/02098 LCD Backlight Controller IC UP800..

Hi All.

Does anyone know if Macbooks will power on without their display backlight controller ICs? Explicitly I have an a2485(very similar to a2442) that has the UP800 IC broken/missing. On attaching a USB PD charger it stays at 5v ~1A for 20 seconds and then resets and repeats the cycle.

The history is that the machine was water damaged to IC UP800. A Renesas 209100b1 Buck Boost controller. The machine still worked, but without the display backlight coming on. UP800 wasn't generating any switching signals to the four driver mosfets. I removed UP800 and check the PCB and surrounding components. Everything tested okay. I cleaned and reballed the IC and put it back on the board. On connecting a USB charger, the machine started power cycling as initially mentioned. I removed UP800 again, but it still power cycles.

When the USB charger is connected, the 3v8 AON rail is good and stable for the 20 seconds the machine is on. The PP5V_S2_MAIN rail switches on and off at about 1Hz, as do the 1v8 and 1v2 rails. It's like the machine is trying to bring up the power rails but fails and resets. I fear I may have messed up the reball and sent power down the I2C or EN lines to the SOC. Although I was quite careful and checked for shorts after the reball. Also, looking at the pin layout of UP800 it's hard to see how any of the power rails could short to the SOC lines. With UP800 removed, there is a weird(non-binary) pulse coming from the SOC on the BL_PWR_EN line and SPMI_DISP_BKLT_DATA steps up to 1.2v, both synchronised with PP5V_S2_MAIN's 1Hz. Nothing on SPMI_DISP_BKLT_CLK. There are no pull-up resistor on the schematic which is weird assuming it's i2c.

I'm currently looking at buying a new UP800 from AliExpress but they are extortionately expensive, so it would be good to work out if the current problem with the machine is just because of the missing backlight controller, or if I've damaged something else and it should still power on without UP800. Any help would be greatly appreciated whether it's about the backlight controller or similar failure modes on M1 Macbooks.

Thanks.

Probably its caused by Renesas 209100b1, but its 200€ on Aliexpres

[Timp74]

Re: 820-02100/02098 LCD Backlight Controller IC UP800..

So to add. Looks like most AON rails are stable. Most S2 rails are switch on for a fraction of a second about every second.

PP1V8_AWAKE is weird. It rises up to about 0.7 volts and then resets with the other S2 rails. It's switched from PP1v8_S2 by U7700. PP1V8_AWAKE measures 0.342v in diode mode and more than 250Kohms. It seems to power the audio ICs and some level shifters. Seems completely unrelated to the backlight IC UP800...

[Timp74]

Re: 820-02100/02098 LCD Backlight Controller IC UP800..

Hi, I have an A2442 with a motherboard problem 820-02098, at first it was damaged by water, I was able to get it fixed but I did not completely, i get error 21 in apple configurator 2 and in DFU mode, I thought that the problem could be NAND it was visually browna little bit, up to here I was able to turn on the mac but the apple logo came out and immediately after restore image , I tried to remove first Renesas 209100b1 and reball it, just to try, maybe it works again, and after removed bad NAND and now It continue boot loop and I don't understand why , visually I checked everything more times and I have no short circuit but it keeps going out so it doesn't even want to turn on,



I attach the link with Google drive with video.


https://drive.google.com/drive/u/0/f...zxndf_CeP3MPNU

Hi, Sounds like you need to work through the power rails again. If it's restarting like in the video, it may not have all _AON rails working.

Thanks for letting me know your opinion on the 209100B1 chip. Did you try turning your a2442 on when the chip was removed? There is an AliExpress seller that has the chips for 50 dollars. Which is still ridiculous, but if I knew it would fix the motherboard I would buy one.

[yra98621]

Re: 820-02100/02098 LCD Backlight Controller IC UP800..

Hi, Sounds like you need to work through the power rails again. If it's restarting like in the video, it may not have all _AON rails working.

Thanks for letting me know your opinion on the 209100B1 chip. Did you try turning your a2442 on when the chip was removed? There is an AliExpress seller that has the chips for 50 dollars. Which is still ridiculous, but if I knew it would fix the motherboard I would buy one.

i originally had problem with backlight not working just while lcd was working, so in any case i have to buy 209100B1 and try if it starts again.

Thanks for the tip on the _AON I will check them again

[Timp74]

Re: 820-02100/02098 LCD Backlight Controller IC UP800..

i originally had problem with backlight not working just while lcd was working, so in any case i have to buy 209100B1 and try if it starts again.

Thanks for the tip on the _AON I will check them again

I hope you can fix it. I'm assuming the 'POWER ALIASES..' pages of the schematic list the power rails in a similar order to which they come up.. Like the 820-02100 I'm trying to fix has all rails up to PP1V8_AWAKE working(S2 rails are oscillating, but they come up to the correct voltage when high). PP1V8_AWAKE is only coming up to 0.7v and PP1V2_AWAKESW_BLC stays at 0v.

BTW. Have you successfully replaced NAND chips in Macbooks before? I thought they were factory programed for the machine they are in and can't be replaced/swapped.. That was written on a forum somewhere so may not be true..

[yra98621]

Re: 820-02100/02098 LCD Backlight Controller IC UP800..

I hope you can fix it. I'm assuming the 'POWER ALIASES..' pages of the schematic list the power rails in a similar order to which they come up.. Like the 820-02100 I'm trying to fix has all rails up to PP1V8_AWAKE working(S2 rails are oscillating, but they come up to the correct voltage when high). PP1V8_AWAKE is only coming up to 0.7v and PP1V2_AWAKESW_BLC stays at 0v.

BTW. Have you successfully replaced NAND chips in Macbooks before? I thought they were factory programed for the machine they are in and can't be replaced/swapped.. That was written on a forum somewhere so may not be true..

Macs with m processors, you can change nand without any programmer, if i can do it then i reply here, same for iphone 12 and up, after you changed, you have to put it in dfu and reinstall the system.

[Timp74]

Re: 820-02100/02098 LCD Backlight Controller IC UP800..

Macs with m processors, you can change nand without any programmer, if i can do it then i reply here, same for iphone 12 and up, after you changed, you have to put it in dfu and reinstall the system.

This is very interesting.. Can you add more NAND to change the size of the SSD?

[yra98621]

Re: 820-02100/02098 LCD Backlight Controller IC UP800..

This is very interesting.. Can you add more NAND to change the size of the SSD?

Yes, you cand upgrade memory and ad more gb, in my iphone 13 i add 512gb from 128gb, and for example this is video for A2442 upgrading memory SSD, NAND

https://www.youtube.com/watch?v=yBwF3_x1Oog

[Timp74]

Re: 820-02100/02098 LCD Backlight Controller IC UP800..

I have given in and paid 50 bucks for a single chip from China. Will post update when it arrives and I try and install it.

I checked all buck and LDO outputs on the master and slave PMICs. All good. The only suspicious thing is that the vpump on the slave PMIC u7700 seems not to come up to 4.9 volts and has different diode/resistance to the master PMIC. This is needed for the switched outputs. So things like PP1v8_AWAKE. I'm assuming this is because it's programmed that way, not because there is a fault on U7700. I can't see how my attempts to fix the backlight controller could have damaged only a very specific part of u7700...

[Timp74]

Re: 820-02100/02098 LCD Backlight Controller IC UP800..

Another possibility. R8170 was slightly corroded so PMU_VDDHI may be wrong. When PPBUS_AON is at 12.4 volts PMU_VDDHI is at 2.45 volts. Could anyone confirm this is the right ratio? There are two different options in the schematic, nether would give this ratio.

Also. The machine can't be loading anything from the EEPROMs as those need PP1V8_AWAKE. This power looping behaviour is probably because of the PMICs. Possibly a sensor out of range, although the majority of those also need PP1V8_AWAKE.. I'm running out of things to check.

[yra98621]

Re: 820-02100/02098 LCD Backlight Controller IC UP800..

This is very interesting.. Can you add more NAND to change the size of the SSD?

Another possibility. R8170 was slightly corroded so PMU_VDDHI may be wrong. When PPBUS_AON is at 12.4 volts PMU_VDDHI is at 2.45 volts. Could anyone confirm this is the right ratio? There are two different options in the schematic, nether would give this ratio.

Also. The machine can't be loading anything from the EEPROMs as those need PP1V8_AWAKE. This power looping behaviour is probably because of the PMICs. Possibly a sensor out of range, although the majority of those also need PP1V8_AWAKE.. I'm running out of things to check.

On 2442 i have PMU_VDDHI 2,56v PPBUS_AON 12,27

[Timp74]

Re: 820-02100/02098 LCD Backlight Controller IC UP800..

On 2442 i have PMU_VDDHI 2,56v PPBUS_AON 12,27

Thanks Yra98621. Did you have any luck with your repairs?

PMU_VDDHI doesn't seem wildly off, so I'm going to look for other causes..

I finally got the RAA209100B backlight buck-boost converter from China. Unfortunately after installing it the motherboard still doesn't work. There are some odd voltages on a few pins. Notably, the BL_PWR_EN signal from U8100 the master PMU to the backlight controller only comes up to about 0.5v, and it's not a very sharp transition. I'm wondering if this is a binary signal or not. Without the backlight converter, it didn't come up at all. Just had a small pulse on it.

So as is. The Macbook is trying to power on, but is resetting the power up sequence every second. It's not getting to the point where the SOC is loading the firmware as PP1v8_AWAKE never comes up properly, and this powers part of the EEPROM. PP1v8_AWAKE also powers most of the current and voltage sensor comparators. PP1v8_AWAKE is from a switch in u7100, the slave PMU. There is a note in the schematic saying that the switches in u7100 need the 4.9v ref on the VPUMP pin enabled. VPUMP is floating around 0.5v, not 4.9v. I'm not sure what enables this.. or if u7100 is bad... As the power up sequence resets, the USB-C charger stays at 5v and oscillates between 0.6 and 1W. Oddly installing the motherboard in the laptop it does the same thing, but the USB-C charger comes up to 20v. The battery doesn't charge, and it again oscillates between 0.6 to 1W. I'm currently trying to work out if the PMUs are resetting before VPUMP should come up, or because VPUMP's not coming up. There was a small amount of liquid damage around some of the ICs that measure the current on PP3V8_AON. These ICs don't depend on PP1v8_AWAKE, and could be giving a bad reading to the master PMU...

[PickledOnion]

Re: 820-02100/02098 LCD Backlight Controller IC UP800..

Thanks Yra98621. Did you have any luck with your repairs?

PMU_VDDHI doesn't seem wildly off, so I'm going to look for other causes..

I finally got the RAA209100B backlight buck-boost converter from China. Unfortunately after installing it the motherboard still doesn't work. There are some odd voltages on a few pins. Notably, the BL_PWR_EN signal from U8100 the master PMU to the backlight controller only comes up to about 0.5v, and it's not a very sharp transition. I'm wondering if this is a binary signal or not. Without the backlight converter, it didn't come up at all. Just had a small pulse on it.

So as is. The Macbook is trying to power on, but is resetting the power up sequence every second. It's not getting to the point where the SOC is loading the firmware as PP1v8_AWAKE never comes up properly, and this powers part of the EEPROM. PP1v8_AWAKE also powers most of the current and voltage sensor comparators. PP1v8_AWAKE is from a switch in u7100, the slave PMU. There is a note in the schematic saying that the switches in u7100 need the 4.9v ref on the VPUMP pin enabled. VPUMP is floating around 0.5v, not 4.9v. I'm not sure what enables this.. or if u7100 is bad... As the power up sequence resets, the USB-C charger stays at 5v and oscillates between 0.6 and 1W. Oddly installing the motherboard in the laptop it does the same thing, but the USB-C charger comes up to 20v. The battery doesn't charge, and it again oscillates between 0.6 to 1W. I'm currently trying to work out if the PMUs are resetting before VPUMP should come up, or because VPUMP's not coming up. There was a small amount of liquid damage around some of the ICs that measure the current on PP3V8_AON. These ICs don't depend on PP1v8_AWAKE, and could be giving a bad reading to the master PMU...

Hi Timp74

I am currently trying to rescue 820-02100 board that has been water damaged.

The backlight area is intact but similar water damage/corrosion around u5700 and isense.

magsafe is 5v, 0-04a - 0.10a and cycling. Cant get 20v on magsafe or usb-c.

I have stable ppbus aon, pp3v8_aon, ppv1v2_aon an,d ppv1v8_aon. However PP5V_S2_MAIN (and enable pin), p3v3_aon, pp1v2_s2 and pp1v8_s2sw and related rails are slowly climbing and dropping to zero and cycling (0v-0.5v-0v or 0v-1.5v-0v etc) roughly half the required rail voltage

It may be fruitless but we could both share diode readings of pmics and backlight etc to see if we can narrow down the issues.

A useful detail about the m1pro/max boards is they will only start up without battery and trackpad etc on the Mag safe connector only and will NOT on the USB-C ports. So best to only test on Mag safe. Thought i would share incase you didnt know.

Anyway I will post some diode readings later.

[mon2]

Re: 820-02100/02098 LCD Backlight Controller IC UP800..

If you do not have 20v, review the LDO rails on the ACE controllers onboard. Each must be working to allow for the 20v power delivery contract to be selected.

What is the exact voltage to ground of PPBUS_AON ?

[PickledOnion]

Re: 820-02100/02098 LCD Backlight Controller IC UP800..

If you do not have 20v, review the LDO rails on the ACE controllers onboard. Each must be working to allow for the 20v power delivery contract to be selected.

What is the exact voltage to ground of PPBUS_AON ?

Thanks for suggestion,. So can charger come up to 20v even if my 3.3v_aon is low and cycling? Also PP5V_S2_MAIN
enable is low. The PPBUS_AON is 12.3v and stable.

[mon2]

Re: 820-02100/02098 LCD Backlight Controller IC UP800..

3.3v_aon is low and cycling?

Can you share the exact netname used in the schematic? Unable to locate 3.3v_aon. Did you mean PPVIN_P3V8AON ?

can charger come up to 20v even if my 3.3v_aon is low and cycling?

If the power rails for the CD3218 ACE controllers have been met, the ACE controllers will function. They are stand alone devices with embedded microcontrollers. Review each of the power pins on these power delivery controllers.

[PickledOnion]

Re: 820-02100/02098 LCD Backlight Controller IC UP800..

Can you share the exact netname used in the schematic? Unable to locate 3.3v_aon. Did you mean PPVIN_P3V8AON ?


If the power rails for the CD3218 ACE controllers have been met, the ACE controllers will function. They are stand alone devices with embedded microcontrollers. Review each of the power pins on these power delivery controllers.

Sorry it's PP3V3_AON

I will check the ace controllers and report bk.