What's new

Question RTC Troubleshooting

Joined
Nov 13, 2022
Messages
240
Likes
109
Hey, everyone! I just installed the MX Chip onto my trimmed Wii (RVL CPU 01 with a Noldendo trim) and almost everything is going great. RVLoader detects the MX Chip itself so there are no worries there, but for the life of me I can't get it to recognize the RTC battery. I've tried wiring it up in multiple configurations, but to no avail. The Wii will still only move the internal clock forward when it is powered on. Does anyone have some kinda diagnosis or suggestions for troubleshooting this? I have a couple specific questions:

1. Does the RTC battery need to be at 3v or can it be slightly lower
2. What are the minimum trim lines of the MX Chip that allows it to retain full RTC functionality (could I have trimmed mine too small)
3. Are there differences when trimming a 6 layer MX Chip compared to a 4 layer
4. Does wire length from the battery to the MX Chip matter
5. Do the presence/absence of other passives on the board affect RTC functionality (small resistors/capacitors, U9, etc.)
6. Am I forgetting something about the RTC Battery's functionality (should it even be doing what I think it should be doing)

I'd love to get the full feature set reinstalled in my Wii Micro, and this is the last thing on my list. Any response is greatly appreciated. God bless!
 
Joined
Mar 20, 2023
Messages
52
Likes
49
Location
'Murica
Hey, everyone! I just installed the MX Chip onto my trimmed Wii (RVL CPU 01 with a Noldendo trim) and almost everything is going great. RVLoader detects the MX Chip itself so there are no worries there, but for the life of me I can't get it to recognize the RTC battery. I've tried wiring it up in multiple configurations, but to no avail. The Wii will still only move the internal clock forward when it is powered on. Does anyone have some kinda diagnosis or suggestions for troubleshooting this? I have a couple specific questions:

1. Does the RTC battery need to be at 3v or can it be slightly lower
2. What are the minimum trim lines of the MX Chip that allows it to retain full RTC functionality (could I have trimmed mine too small)
3. Are there differences when trimming a 6 layer MX Chip compared to a 4 layer
4. Does wire length from the battery to the MX Chip matter
5. Do the presence/absence of other passives on the board affect RTC functionality (small resistors/capacitors, U9, etc.)
6. Am I forgetting something about the RTC Battery's functionality (should it even be doing what I think it should be doing)

I'd love to get the full feature set reinstalled in my Wii Micro, and this is the last thing on my list. Any response is greatly appreciated. God bless!
I also had similar issues with my micro. I believe the issue was caused by me damaging the passives near TP118. Some pictures of the MX trim and wiring would help. The nominal voltage on a standard lithium CR2032 is 3.0v. It can be a little lower, but lower than 2.8v and capacity drops off dramatically. A new one should be 3.1-3.2v. Wire length shouldnt matter much since it consumes microamps (don't overdo it obv). I believe the 6L and 4L MX are practically the same, so make sure it's wired to TP118. You can try to bypass the passives and wire to TP116 and check if it works, but you're bypassing the overcurrent protection and the battery would last for only 72 hours or so. Best of luck!
 
Joined
Nov 13, 2022
Messages
240
Likes
109
I also had similar issues with my micro. I believe the issue was caused by me damaging the passives near TP118. Some pictures of the MX trim and wiring would help. The nominal voltage on a standard lithium CR2032 is 3.0v. It can be a little lower, but lower than 2.8v and capacity drops off dramatically. A new one should be 3.1-3.2v. Wire length shouldnt matter much since it consumes microamps (don't overdo it obv). I believe the 6L and 4L MX are practically the same, so make sure it's wired to TP118. You can try to bypass the passives and wire to TP116 and check if it works, but you're bypassing the overcurrent protection and the battery would last for only 72 hours or so. Best of luck!
Thanks so much for touching on everything! Sorry about the photos, forgot to include them:
604F9931-51BC-45AF-9083-062887BF5721.jpegCDFF5D65-0966-4307-A6DC-C5BAD9802F2B.jpeg
By passives, do you mean the group of 3 chips right next to TP118?
B4774215-115A-4C2B-8693-1F25C8A53CB3.jpeg

I have a different MX Chip I can try, but first I’m gonna wire it straight to TP116 and see if it works then. I’ll know I got it right when I turn the trim off and it says 12:00, then wait 3 minutes later and when I turn it back on it says 12:03, right (not necessarily those specific numbers, just trying to illustrate the passage of time)?
 
Joined
Mar 20, 2023
Messages
52
Likes
49
Location
'Murica
Yeah that should be good. There's also a homebrew NTP app I used but that shouldnt be needed for a test lol. And yes those are the passives.
 
Joined
Nov 13, 2022
Messages
240
Likes
109
Okay, so I did a little experimenting. I can confirm that the passives on my first MX Chip must be broken because the RTC worked perfectly when wired up to TP116. So, I swapped it out for another MX Chip to see if the passives on that one functioned normally. They don't. For some reason, now the time will jump huge gaps when the console is turned off, going from 12:43 on one boot to 2:13 a second later when I boot it up again! And TP116 doesn't work at all on this one. I have one last MX Chip I can try, and I'm praying this one works completely normally...
 
Joined
Mar 20, 2023
Messages
52
Likes
49
Location
'Murica
Okay, so I did a little experimenting. I can confirm that the passives on my first MX Chip must be broken because the RTC worked perfectly when wired up to TP116. So, I swapped it out for another MX Chip to see if the passives on that one functioned normally. They don't. For some reason, now the time will jump huge gaps when the console is turned off, going from 12:43 on one boot to 2:13 a second later when I boot it up again! And TP116 doesn't work at all on this one. I have one last MX Chip I can try, and I'm praying this one works completely normally...
Afaik the only important passive is the resistor R60, which is a 1kohm resistor in series with the battery (to TP116). There should be several on the motherboard scrap from trimming but it'll be hard to identify on a 6 layer i assume. You can also remove and short the diode pads as thats only for reverse polarity protection (which isn't important on a soldered battery). If you dont have any of that package laying around, maybe you can try soldering a PTH one instead. Ofc if the last chip works then thats perfect, but the first one is probably fine.
 
Joined
Nov 13, 2022
Messages
240
Likes
109
Okay, so good news. I got the MX Chip and RTC Battery working! And then I broke it! :facepalm:

I don’t know if anyone was aware of this before, but you can actually trim the U10 and U9 pads out of an MX Chip and it will still retain all functionality.
9CFC0B93-4D9C-41E9-99EC-B18BFAC4FBB6.jpeg

I hooked this up to my Wii Micro, and everything worked perfectly: MX Chip was recognized and the RTC battery worked as normal from the TP118 pad. But then, I must have done something to it while trying to resolder some wires, because now it straight up prevents the Wii from booting. I figured out what’s causing this: somehow Pin 17 (3.3v) is shorted to Pin 16 (GND). This connection is 100% not visible, as the pins have no solder bridge. It may be caused by some hidden flux residue, so I’m going to give one last thorough clean. Has this issue ever happened to anyone else before?
 
Joined
Nov 13, 2022
Messages
240
Likes
109
Only 600, but it worked before with that grit so I don’t think it’s the issue. I removed both that 3.3v pin and all the GND pins from the board (now they’re just connected to the MX Chip itself) but for some reason that 3.3v pin is still shorted to all GND. Also, none of the other 3.3v pins are shorted to GND. I have no idea what’s going on
 
Joined
Nov 13, 2022
Messages
240
Likes
109
Have you sanded properly up to 800 grit sandpaper in the concave cut? That could be your issue.
Actually, I think you were right about the sanding! I experimented with a bunch of my MX Chips today, and found out that after resanding the edges, the short disappeared. I still did it only up to 600 grit, but now it works no problem. Still not recognizing the RTC battery though... :(
 

Stitches

2 and a Half Dollarydoos
Staff member
.
.
Joined
Feb 5, 2017
Messages
4,242
Likes
3,307
Location
Banana Bender Land, Australia
Portables
6
Progress is progress! What does the battery's voltage read when it's not connected to anything?
 
Joined
Nov 13, 2022
Messages
240
Likes
109
Around 2.8-2.9 volts. Judging by how the Wii handles other voltages, I figure if’s enough, although correct me if I’m wrong
 

Stitches

2 and a Half Dollarydoos
Staff member
.
.
Joined
Feb 5, 2017
Messages
4,242
Likes
3,307
Location
Banana Bender Land, Australia
Portables
6
That should be fine. 3v coin cells are considered depleted between 2 and 2.25v depending on model, and CMOS systems are usually configured to use the full duty cycle of the cells. The cells will often come loaded a smidge above 3v, so 2.8v would be a bit low if it's a brand new cell, but it's well within the operational range regardless.

What kind of coin cell specifically are you using? CR2032?
 
Joined
Nov 13, 2022
Messages
240
Likes
109
Whatever the one that came with the Wii is. I just ripped it straight from the one I trimmed
 
Joined
Nov 13, 2022
Messages
240
Likes
109
So no luck repairing my (4) MX Chips, definitely not a skill issue :/ Seriously though, I could not figure out whether the RTC issues were caused by some sort of short along the edge or some issue with the passives underneath the board. Are 4 layer MX Chips compatible with 6 layer Wiis? Would I be legally able to buy one from someone on BitBuilt for use in my competition project or do I need to trim it myself?
 
Joined
Mar 20, 2023
Messages
52
Likes
49
Location
'Murica
So no luck repairing my (4) MX Chips, definitely not a skill issue :/ Seriously though, I could not figure out whether the RTC issues were caused by some sort of short along the edge or some issue with the passives underneath the board. Are 4 layer MX Chips compatible with 6 layer Wiis? Would I be legally able to buy one from someone on BitBuilt for use in my competition project or do I need to trim it myself?
I have recently attempted another MX relocation and got the same issue here. When soldered to TP118, the time stayed, but didn't advance. So logically, I tried TP116 and that worked as intended. So I then tried relocating the passives from another board (even though there weren't any signs of damage). And yet, the problem persisted. I feel like this is a deeper issue and should be investigated if possible. I've been contacted by a person in the past who had a similar issue, but soldering to TP116 didn't fix it. I'm at a loss for what could be causing it. And if I remember correctly, this same chip was working fine months ago when I left off the project. The best course is probably to extract another mx daughter board, at the cost of another Wii...
1722567092362.png
 
Joined
Mar 20, 2023
Messages
52
Likes
49
Location
'Murica
So I have spent a few hours narrowing down everything I could. At first, I started by replacing the bottom battery passives with ones from other Wiis. Even after several different components, the result ended the same: Battery Voltage at 3.0V (TP118) and the same at TP116 after reconnecting the battery with the Wii off. After a power cycle, TP116 voltage would reduce to 2.0V, effectively disabling the battery. Even bypassing the resistor or pumping more voltage through TP118, TP116 would always have a big voltage drop down to the low 2s. I ended up reflowing and replacing the MX chip with 3 other ones. Alas, nothing changed. I swear I started to think this daughterboard was cursed. But after help from YveltalGriffin, I ended up doing some tests on an untrimmed, unmodded board (atleast with the tools available). The first thing that came to mind were the U9/10 chips. I tested RTC with them on and it worked, as suspected. But after removing both of them with the battery on, then "power cycling" the Wii (Hollywood obv not turning on due to the lack of u10), I GOT THE SAME PROBLEM! TP116 goes down to 2.0V even if the Battery is full at 3V. I then verified that the RTC issue occured by performing the wireless U10 relocation and actually booting into the menu. I then had the idea to solder U9 back on (for whatever reason), and to my surprise.... the problem went away. I was shocked at the result, and had to try on the trimmed daughterboard. After reworking the 3.3v wiring (using the traditional power routing without the crazygadget's shortcut. And more importantly, NOT SHORTING PIN 25 AND 24 WITH 3.3V)....


I think I fixed it...
1722725280645.png
1722725235133.png

1722725308546.png


Now, this doesn't explain how people have relocated MX without U9 (as intended) and had RTC working perfectly. Maybe its a trim line/power routing issue? Maybe the MX chip just tweaks out sometimes without that U9 signal? Alas, I haven't probed current draw, but it's safe to say it's working as normal with that current limiting resistor. I still think there should be more research done into it, but this seems like a fix! Hope this helps!


TL;DR: Keep or solder U9 back onto the original pads. Follow original MX wiring guide except keep pin 25 "floating", do wire 3.3v everywhere else.
 
Joined
Nov 13, 2022
Messages
240
Likes
109
I’ll give it a try as soon as I track down my MX chips. Incredible job on the research, both me and the community really appreciate the time you put into figuring this out. Here’s to more successful troubleshooting in the future!
 
Top