[SOLVED] I'm looking for Samsung SM-G920D SGH-N520 Galaxy repair guide or schematics (free) - Phones & Tablets Forum

Hi,

I'm hoping you can help me out with my Samsung SM-G920D SGH-N520 Galaxy. It's started acting up, and I'm looking for a detailed service manual with boardviews and schematics to properly diagnose and repair it. I need to take precise voltage measurements around the board, so having the right documentation would be very helpful.

Thanks in advance for your help.

Selected Answer

I actually found that service manual on a tech Discord server a while back. A really helpful member there shared a direct link to their blog and I've saved it. I'm happy to pass it along here. Hopefully, these boardviews and schematics help you fix your phone, just like they got me through my repair. Looks like we have the same model.

@Claude

Absolute legend! That's exactly the info I was searching for. This is going to save me so much time probing in the dark. Seriously, thanks a ton for sharing the link!

Hi there,

I also have the Samsung SM-G920D SGH-N520 Galaxy and just downloaded the manual you shared. I'm pretty new to board-level phone repair, and this is a bit intimidating with all the tiny test points and the schematics. Could you point me in the right direction on how to start troubleshooting this ? Any advice on the first few things I should check would be a massive help.

Thanks so much for your time

General advices: start by checking the voltage at the battery connector on the board. With a known-good battery connected, you should see a steady voltage between 3.7V and 4.2V. After that, a great next step is to check the main power management IC (PMIC) for shorts. Using your multimeter in diode mode, check for shorts on the large input capacitors surrounding the PMIC.

Here are a few useful references for troubleshooting your device:
https://www.ifixit.com/Guide/Slime+Portable+Air+Compressor+Motor+Replacement/64664
Take a look at comment #575
Also, this : https://xdaforums.com/t/from-htc-one-s-to-oppo-find-5.2290499/.
You can also check this video starting from minute 1:

The Samsung SM-G920D SGH-N520 Galaxy service manual and boardviews from the link above were exactly what I've been searching for. I couldn't find a complete, free copy anywhere else. Seriously, thank you for sharing this you're a lifesaver!

Hi everyone, I'm working on a Samsung SM-G920D SGH-N520 Galaxy with a no power issue and need some guidance with my measurements.
I'm detecting 3.3V on the VREG_MAIN line (pin 1 of the PMIC), which looks good, but I'm getting 0V on the VDD_CPU line (pin 8) where the schematics indicate I should see about 0.9V.
Since this is a core voltage for the application processor, could this missing rail be why the device shows no signs of life?
What's the best procedure to diagnose this further? Should I check for shorts on the CPU rail first, or look at the PMIC's enable signals?
I've already verified the main 3.3V and 1.8V power rails are present and stable.

My Samsung SM-G920D SGH-N520 Galaxy was working perfectly until yesterday when it suddenly went completely dead. Now it won't respond to the power button, doesn't vibrate, and shows no signs of life even when connected to a charger. I'm worried there might be a serious issue.

I have a decent multimeter, a basic soldering iron, and a healthy dose of patience. While I've successfully replaced iPhone batteries and charging ports, this will be my first attempt at actual diagnosis. The sheer density of BGA chips and microscopic components is honestly a bit overwhelming.

I'm particularly curious about the alcohol trick I've seen online where you apply isopropyl to the board and look for evaporation hotspots to locate shorts. Is this actually a reliable method for beginners, or are there better approaches I should try first with just a multimeter?

I learned this lesson the hard way last month with mine, it was declared "dead" by two different shops. The phone showed absolutely no signs of life - no charging indicator, no vibration, nothing. Before diving into complex board work, I decided to try one more basic test: wireless charging.

To my complete surprise, it actually heated up on the charging pad! This single discovery completely changed my diagnostic path. It turned out the issue wasn't with the main board or processor, but with the notoriously fragile USB-C port that had failed completely. A $15 replacement part and some careful soldering brought it back to life.

The moral? Always exhaust every external testing method before opening the device. Test wireless charging if available, try different charging methods, and don't assume the worst case scenario. Sometimes the most "dead" devices have the simplest solutions hiding in plain sight.

I suspect my issue might be related to that cheap, third-party fast charger I used at the airport last week... Now the device gets extremely hot during charging, the screen flickers at low brightness, and sometimes it randomly shuts down at 30% battery. Could this have damaged the power management IC or battery calibration?

If your Samsung SM-G920D SGH-N520 Galaxy starts acting up, random reboots, fast battery drain, or connectivity issues, there are several diagnostic steps you can take before assuming the worst:

• Check your charging habits: Using poor-quality chargers or wireless pads can gradually damage your battery and charging circuit, leading to unpredictable behavior.
• Inspect the physical components: A slightly damaged charging port, worn battery, or even accumulated pocket lint can cause issues that seem like major hardware failures.
• Monitor temperature patterns: If your phone gets unusually hot during specific tasks (like camera use or gaming), it could point to a failing component rather than a software issue.
• Use diagnostic tools wisely: Ampere for battery health, phone diagnostic codes (*#0*# on many models), and a thermal camera can reveal problems without opening the device.
• Know when to stop: If you see liquid damage indicators tripped or smell burnt electronics, it's time to consult a professional before causing irreversible damage.

Also visit this link it may help : https://xdaforums.com/t/my-sgs3-is-rooted-i-just-recieved-an-ota-update-but.1873235/

Here's what I discovered on forums and technical databases:

While earpiece speaker replacement doesn't typically threaten your data, any unforeseen issue during disassembly or reassembly could lead to data loss. As the solder under the reader and on its pins melts, the component should "settle" or "snap" into place due to surface tension. For phones where the antenna flex cable is easily accessible (e.g., in some modular designs), check for any visible damage or loose connections. Keep the heat source moving constantly to prevent overheating any single spot, which could damage internal components like the camera sensor itself or the surrounding plastic frame. Advanced diagnosis involves checking its input and output voltages with an oscilloscope, if possible. Power on the device and immediately test the camera functionality extensively. Liquid ingress can corrode the microphone's electrical contacts, short-circuit the internal components, or damage the membrane, leading to distorted, intermittent, or completely non-functional audio. This is extremely complex as Baseband ICs are often "married" to the main CPU and other security chips on the board. Safety Hazard: In the worst-case scenario, severe overheating can cause the battery to swell, rupture, or catch fire. Double-check that the battery connector is aligned properly before attempting to plug it into the motherboard. A faulty PMIC can mismanage power, leading to overheating in certain areas. Oxidation: A natural chemical reaction with oxygen, forming a non-conductive layer on metal surfaces. Therefore, evaluating smartphone haptic response delays is crucial when diagnosing a device's responsiveness, particularly if the user complains about a "laggy" or "unresponsive" feel. This procedure should only be performed on a device that you legitimately own or have explicit permission from the owner to modify. Diagnostic Modes: Use any available diagnostic modes to check signal strength and transmit power. Equally problematic is slow charging, where the phone charges at an unacceptably sluggish rate, barely keeping pace with consumption, often indicating a failure to agree on optimal charging protocols like Quick Charge or USB-PD. Overheating: Localized or general overheating, even when idle or not charging. Troubleshooting a non-vibrating smartphone is usually a process of elimination, starting with the most straightforward software solutions and progressing to hardware components. Charger/Cable: Does it happen with all chargers and cables, or only specific ones? (Crucial clue!) Damage to this chip or its surrounding components can cause the "invalid battery" error. Red Flag: If the price is significantly lower than average for a genuine part, it's almost certainly a fake or a very low-quality aftermarket copy. Cut the Adhesive: Carefully slide the opening pick around the perimeter of the phone, slowly cutting through the adhesive. This visual storytelling can be highly effective in training and quality control. Power on and perform a comprehensive test of the touch functionality across the entire screen. It might be lightly adhered to the frame; use a plastic spudger to gently pry it up. The cellular modem (the chip responsible for processing cellular signals) or the internal cellular antenna could be damaged. Incorrect Fit: The new screen might not fit perfectly into the frame, leaving gaps or creating pressure points. Maps/Navigation Issues: Map applications show the user icon spinning erratically or pointing in the wrong direction, making navigation difficult. Disconnect Bluetooth Devices: If your phone is wirelessly connected to Bluetooth headphones, speakers, or a car system, audio will be routed there. Flux (for soldered ports): No-clean liquid or paste flux to promote solder flow and clean surfaces.

@Rahul, Not sure what you're trying to say but ok :)