Facing a baseband issue on your iPhone XR? This common problem can prevent the device from activating, displaying “No Service,” or failing to detect a mobile network altogether. In this article, we guide you through a real-world iPhone XR baseband issue repair case — covering precise diagnostics, baseband CPU resoldering, and transceiver IC replacement. Whether you’re a technician, repair shop, or DIY enthusiast, this guide provides actionable insights to help you fix the issue and avoid common repair mistakes.
Important Pre-Repair Tip
If your iPhone XR has no baseband o no signal, DO NOT restore or recover the phone before repair.
A device that’s restored with a baseband issue becomes unrepairable, effectively turning it into a non-functional unit.
If left unrestored, even if it can’t be repaired, it can still function as a Wi-Fi-only gaming device.
iPhone XR Baseband Issue Repair Process
Paso 1: Diagnóstico inicial
We received an iPhone XR with a baseband issue — it had been previously serviced by another repair shop, but the problem persisted. Upon opening the device:
- The shielding cover over the baseband chips had been removed.
- The NAND chip had been resoldered and sealed with black glue.
- The area around the baseband CPU (U_BB_K) showed blackened capacitors and resistors — a clear sign of corrosion from poor-quality solder paste.
Step 2: Resoldering Surrounding Components
To start:
- Aplicada rosin flux to the affected area.
- Used a pistola de aire caliente to reflow and resolder the small passive components around the baseband CPU.
- Cleaned the logic board using Limpiador de PCB for better visibility and soldering results.
Step 3: Removing and Inspecting Baseband CPU
After removing the U_BB_K (baseband CPU):
- Scratch marks were found near the chip — likely due to scraping by the previous technician.
- Fortunately, no damage to the internal PCB layers was detected.
- The old solder was identified as pasta de soldadura de baja temperatura — it melts easily but has poor bonding strength and causes corrosion.
We then resoldered the baseband CPU using medium-temperature solder paste, ensuring a more durable and reliable connection.
Después de reemplazar el transceptor IC con uno nuevo, y luego restaurarlo con iTunes la banda base y la función de señal de nuevo a la normalidad.
Resumen
El problema es causado por la CPU de banda base y el transceptor IC, el taller de reparación anterior reparó las dos partes. Pero debido al mal trabajo de soldadura y a la mala calidad de la pasta de soldar, el problema no se soluciona completamente.
Lecciones aprendidas de este caso, haz más prácticas manuales si quieres ser un experto en reparaciones, y utiliza materiales de reparación cualificados, ¡no sueldes el chip Baseband con pasta de soldar a baja temperatura!