One of the common issues seen in Vivo Y15S devices when it comes to network usage is “No Service”, Vivo Y15S Network Problem or “Emergency Calls Only”. These kind of problems are not uncommon for mobile technicians and hardware technicians. While a simple software issue may be resolved through a reset or firmware update, more serious issues are usually related to the motherboard of the device. Usually, it all relates to the RF (Radio Frequency) area of the printed circuit board. This post provides a complete troubleshooting guide, with the supplied high-resolution PCB image, to assist companies with fault analysis and repair on Vivo Y15S devices.
The Network Section of the Vivo Y15S
The network section of the Y15s controls all cellular communication (voice calling, SMS, mobile data (2G/3G/4G), etc.). The network section consists of several integrated circuits (ICs), surface-mounted devices (SMDs), etc. These devices communicate via the copper tracks on the mainboard. A defect anywhere along these tracks, connector points, or in the IC itself can lead to a loss of signal or an overall network failure.
Vivo Y15S Network Problem | Schematic Jumper Ways
Component Identified:
The major devices in the upper right of the image relate to the network transmission and reception subsystem. These chips will have band-specific filters and antenna connectors and SIM slots.
Colour-coded PCB Tracking:
The green lines identify paths such as RF_ANT_PRX_ANT_TXM that relate to the transmission and reception of signals from the antenna.
Yellow and Orange tracks represent the primary RF bands (RF_B1_TRX_TXM) that form the main transmit and receive signals.
Purple, Pink, and Red lines are additional band paths which are secondary to the primary ones, which include 2G, multi-band RF Traced signals, etc. (RF_2G_LBT_RX_RFIC, etc.)
The label connection points & labelled IC pins are identifiable for each colored route leading specifically to a pin or SMD (which may be a resistor, capacitor, coil, or pad).
How To Repair Vivo Y15S Network Problem:
- Use a magnifier to examine the board for rust, burn marks, cracks, and loose solder.
- Pay special attention to the areas with a ton of small chips and around the network IC area.
- Look for any tiny cracks that can possibly break important network connections.
- Use a multimeter and a colour diagram to test all the board lines and record any line that is not connecting, and which IC it is.
- If solder joints are dull or broken, gently heat them with a hot-air tool – focusing on the pins listed in the colour diagram.
- Replace any shorted or damaged small parts (capacitors, resistors or coils) and replace the IC only if it is faulty.
- If the board tracks break, you can use a thin wire to reconnect the path, using the colour guide, and secure the wire with glue or tape.
- After repairs are made, reassemble the phone and add a working SIM, and check if you have network signals (2G/3G/4G) new indoors and outdoors.
- You can check the status of the network with codes such as ##4636## to verify that it is registered.
- You can complete the process by verifying calls, mobile data and the SIM detection are all working to finalize the network repairs.
