2019 MacBook Pro 16-inch that came in with a no display issue, despite the power being on. The customer described the problem simply: “Power is on, no display.” Upon inspection, we found the fans were spinning, and the board was warm, indicating that the system was running but not displaying an image.
Table of Contents
Restart your MacBook
Performing a hard restart can resolve temporary system glitches that might be causing the black screen.
- Press and hold the Power button for about 10 seconds, then release it.
- After the computer power down completely, press the Power button again to turn on your MacBook.
Perform a hard reset.
Press and hold your power button for fifteen seconds, then release. Wait a few seconds, then try to power on again. This can resolve any minor hang ups in the startup process or resolve a stuck update.
Try resetting the PRAM/NVRAM
If you have an Intel-based Mac, resetting the PRAM/NVRAM (both computer memory types) can fix settings issues.
💡 Diagnosis:
When we looked closely, we noticed a dim image on the screen, which meant that the LCD was working, but the backlight circuit had failed. A faulty backlight circuit can be caused by:
✔️ A damaged LCD panel
✔️ A faulty flex cable connecting the LCD to the motherboard
✔️ A motherboard issue affecting the backlight circuit
To pinpoint the problem, we referred to the MacBook’s circuit schematics and focused on the PPVOUT_S0_LCDBKLT line, which controls the LCD backlight power. After tracing the backlight driver circuit, we found a suspicious area near the L8452 inductor and capacitor array.
🛠️ Repair Process:
1️⃣ Checked voltage output at L8452 and found a low 0.5V reading, indicating a possible short.
2️⃣ Injected voltage into the circuit and used a thermal camera to detect overheating components.
3️⃣ Identified a faulty capacitor (C8462) causing the backlight failure.
4️⃣ Removed the damaged capacitor and replaced it with a brand-new 2.2μF 1206-sized capacitor from our stock.
5️⃣ Powered the MacBook back on, and 🎉 the backlight was fully restored!
✔️ MacBook now working perfectly
✔️ No more dim screen issue
✔️ Customer saved from costly LCD replacement!
ReformTech is a highly reliable Laptop and Smartphone repair service provider that offers on-site repairs for various brands. We specialise in fixing hardware issues, including screen replacements, keyboard replacements, RAM upgrades, SSD upgrades, and even motherboard repairs. Contact us at 8100257620 for fast and efficient service.
