Hey all, I have an issue with a Switch lite. After installing a picofly, I powered on to test and saw a puff of magic smoke but I’m not sure from where it originated. I immediately powered down the system to check for damage and didn’t see any burned components, but I noticed the lcd driver (8316 chip) was cracked in the corner. The system still powers on and I have backlight but no display. I replaced the 8316 chip but no dice, so I started checking voltages and one of the test points near the lcd driver measures 1.8v (normal), but the other measures 0v and this is the one that comes from the SOC. So the lcd isn’t even being told to turn on I think these voltages stem from the MAX77620h chip on the back of the board, but not sure. Where would be a good place to begin to troubleshoot this? Or am I completely screwed here?
The system powers on and the backlight, sound, and touch all work fine. I just can’t see anything lol. I have uninstalled the modchip to rule out the possibility of improper or bridged solder joints. I’ve also double checked the screen fpc connector and ribbon cables to see if there were bent pins, but all is well. Thanks in advance for any guidance.
Issues like this wouldn’t ordinarily cause the failure of the 8316 IC as none of the rails relate (well not direcly, a couple indirectly), best guess is you accidentally got solder spatter somewhere where it shouldn’t be or the LCD ribbon was a skew / something in it.
Given this though and the symptoms (which are inline with a failed 8316 IC or support circuitry) it does sound like the IC and/or related support circuitry probably did fail.
If you can find my image on the IC referencing the voltages etc for the regular rev switch board/s you should be able to cross corelate all locations of interest on the Switch lite board by virtue of the components (which afair are all the same, size etc) and identify where you should be measuring.
After I’d then check the positive 5V rail and also the negative 5V rail are present after prompting the console to boot (pwr button/USB) , if no, check the if enable lines signals are high (at 1.8V) , if these points are not obvious or clear on lite (sorry i don’t recall and don’t have a lite board handy to check) then if you’ve got a donor then check in continuity where the B3 and B4 pads come out (or pull the IC and check on your patient). If on the other hand the enable signals are present (and correct voltage) but you don’t get the +/- 5V rails then this likely indicates an issue with support circuitry, most likely would be one or both of the two diodes in the vicinity or possibly one of the nearby related resistors (open/missing/bad)
I’d also take another (i know you said you checkeed but it doesn’t hurt to do it again ) very close look over the board for general issues such as solder spatter / bridges etc as well as the LCD ribbon and also the LCD connector and ensure no damage/bent pins etc.
When you replaced the 8316 IC, was this a new preballed IC from a reputable source (mouser, rapid etc?) . If you want, you can also upload an image of this area and the area related to the modchip solder points for use to take a look at, maybe something will jump out.
I resolved the issue last night Yeah there was a failed open resistor near the IC. I replaced the resistor and at first there was still no display but I noticed that the +5v/-5v were present when they weren’t before, so that indicated that the IC was installed properly and doing it’s job. Then I turned my attention to the fpc connector. It looked ok but I changed it out with a new one and voila! The display now works!
However, I have 2 new problems: no buttons work except for home, and the touchscreen has a dead spot on the right side. Ugh, this thing is gonna be the death of me lol. I know that the STM32 chip handles the button inputs so I’ll see if there’s any obvious issues in that area. Everything worked fine before the modchip install, but maybe it got blown out. Thanks for your reply and suggestions though! I’ve gotten so much insight from reading your posts.
I think these voltages stem from the MAX77620h chip on the back of the board, but not sure. Where would be a good place to begin to troubleshoot this? Or am I completely screwed here?
) very close look over the board for general issues such as solder spatter / bridges etc as well as the LCD ribbon and also the LCD connector and ensure no damage/bent pins etc.