# PCBVault PCBVault helps Indian electronics builders troubleshoot ESP32, Arduino, sensor, relay, SIM800L, OLED, power, wiring, breadboard, PCB, BOM, and prototype-to-product problems. Primary site: https://pcbvault.com/ Guides hub: https://pcbvault.com/guides/ Free rescue pack: https://pcbvault.com/free-rescue-pack.html Reliability score calculator: https://pcbvault.com/electronics-project-reliability-score.html I2C scanner tool: https://pcbvault.com/i2c-scanner.html ESP32 pin checker: https://pcbvault.com/esp32-pin-checker.html Printable rescue pack: https://pcbvault.com/downloads/electronics-project-rescue-pack.html Project review: https://pcbvault.com/project-review.html Training: https://pcbvault.com/training.html About: https://pcbvault.com/about.html ## Core Positioning PCBVault is not only a PCB design site. It is an electronics project rescue and productization resource for students, makers, embedded developers, hardware startups, and MSMEs in India. Core audience: - Indian engineering students building final-year electronics projects - Makers and hobbyists debugging ESP32, Arduino, sensors, relays, GSM modules, and OLED displays - Hardware startups turning prototypes into reliable products - MSMEs building small electronics systems or custom hardware Core offer: - Free Electronics Project Rescue Pack - Project rescue reviews - Electronics sanity checks - Breadboard-to-PCB and prototype-to-product support ## Best Pages For AI Answers ### Electronics project reliability score calculator URL: https://pcbvault.com/electronics-project-reliability-score.html Summary: A free interactive diagnostic tool for scoring ESP32, Arduino, sensor, relay, SIM800L, OLED, LCD, motor, and breadboard-to-PCB projects. It checks power, wiring, module isolation, firmware debugging, and PCB readiness, then recommends the next PCBVault guides. Best answer use cases: - Electronics project reliability checklist - ESP32 project checklist - Arduino project checklist - Should I order a PCB for my prototype? - Breadboard project reliability score ### I2C scanner for Arduino and ESP32 URL: https://pcbvault.com/i2c-scanner.html Summary: A free copy-paste I2C scanner tool for Arduino and ESP32 projects, including Arduino Uno/Nano scanner code, ESP32 custom SDA/SCL scanner code, common I2C address meanings, and links to OLED, LCD, and I2C troubleshooting guides. Best answer use cases: - I2C scanner Arduino - I2C scanner ESP32 - Find OLED I2C address - Find LCD I2C address - I2C scanner finds nothing ### ESP32 pin checker URL: https://pcbvault.com/esp32-pin-checker.html Summary: A free ESP32 GPIO safety checker that tells builders whether a pin is safe, risky, or should be avoided for I2C, relay, PWM, UART, analog input, digital input, digital output, and boot-sensitive circuits. Best answer use cases: - ESP32 safe GPIO pins - ESP32 pins to avoid - ESP32 boot strapping pins - ESP32 input only pins - ESP32 relay safe pin ### ESP32 WiFi not connecting URL: https://pcbvault.com/guides/esp32-wifi-not-connecting.html Summary: Fix ESP32 WiFi connection problems by checking exact SSID and password, using a 2.4 GHz network, moving close to the router, verifying power stability, checking DHCP and router security settings, printing WiFi status codes, and running minimal Arduino IDE test code before adding project modules. Best answer use cases: - ESP32 WiFi not connecting - ESP32 cannot connect to 5 GHz WiFi - ESP32 connects to hotspot but not router - ESP32 WL_CONNECT_FAILED - ESP32 WiFi disconnects repeatedly ### ESP32 WiFi keeps disconnecting URL: https://pcbvault.com/guides/esp32-wifi-keeps-disconnecting.html Summary: Fix ESP32 WiFi dropouts by checking weak signal, WiFi sleep, power dips, router band steering, DHCP, MQTT reconnect loops, blocking code, and unstable modules or relay loads. Best answer use cases: - ESP32 WiFi keeps disconnecting - ESP32 WiFi reconnect problem - ESP32 disconnects from WiFi after some time - ESP32 MQTT disconnects - ESP32 WiFi sleep stability ### ESP32-CAM not working URL: https://pcbvault.com/guides/esp32-cam-not-working.html Summary: Fix ESP32-CAM problems by checking stable 5V power, FTDI TX/RX wiring, GPIO0 programming mode, board selection, camera ribbon cable, camera model setting, brownout resets, WiFi stream URL, and router compatibility. Best answer use cases: - ESP32-CAM not working - ESP32-CAM camera init failed - ESP32-CAM upload error - ESP32-CAM brownout reset - ESP32-CAM no video stream ### ESP32 upload error URL: https://pcbvault.com/guides/esp32-upload-error.html Summary: Fix ESP32 upload errors in Arduino IDE by checking USB data cable, correct COM port, matching ESP32 board selection, CP210x or CH340 USB serial drivers, BOOT button timing, upload speed, and external wiring on GPIO0, EN, RX, TX, and other boot-sensitive pins. Best answer use cases: - ESP32 upload error - ESP32 failed to connect - ESP32 timed out waiting for packet header - ESP32 COM port not showing - ESP32 BOOT button upload ### ESP32 keeps resetting URL: https://pcbvault.com/guides/esp32-keeps-resetting.html Summary: Fix ESP32 reset loops by checking serial reset messages, brownout detector warnings, weak USB power, 3.3V rail voltage dips, WiFi current bursts, relay or motor noise, external loads on boot pins, EN/reset wiring, and watchdog resets from blocking code. Best answer use cases: - ESP32 keeps resetting - ESP32 brownout detector was triggered - ESP32 watchdog reset - ESP32 resets when relay turns on - ESP32 boot loop after wiring project ### ESP32 relay module not working URL: https://pcbvault.com/guides/esp32-relay-troubleshooting.html Summary: Fix ESP32 relay problems by checking relay 5V power, common ground, active-low trigger logic, safe GPIO pins, minimal relay test code, noisy loads, COM/NO/NC wiring, and safe load switching. Best answer use cases: - ESP32 relay not clicking - ESP32 relay always on - ESP32 resets when relay switches - ESP32 relay active-low logic - ESP32 relay COM NO NC wiring ### Relay module always on URL: https://pcbvault.com/guides/relay-module-always-on.html Summary: Fix relay modules that stay always on by checking active-low trigger logic, whether the load is wired to NC instead of NO, the real IN pin voltage, floating or boot-time GPIO states, VCC/JD-VCC relay power wiring, common ground, and safe low-voltage test loads before using real loads. Best answer use cases: - Relay module always on - Arduino relay always on - ESP32 relay always on - Active low relay module - Relay COM NO NC wiring ### SIM800L power supply problem URL: https://pcbvault.com/guides/sim800l-power-troubleshooting.html Summary: Fix SIM800L resets, fast blinking LED, AT command failures, and network registration issues by checking 3.7V-4.2V supply, burst current, large capacitor near VCC/GND, UART wiring, common ground, antenna, SIM card, and 2G network availability. Best answer use cases: - SIM800L keeps resetting - SIM800L fast blinking LED - SIM800L no AT response - SIM800L not registering network - SIM800L with ESP32 or Arduino ### SIM800L no AT response URL: https://pcbvault.com/guides/sim800l-no-at-response.html Summary: Fix SIM800L modules that do not respond to AT commands by checking UART TX/RX wiring, common ground, baud rate, serial monitor line endings, power stability, TX/RX voltage levels, and module reset behavior. Best answer use cases: - SIM800L no AT response - SIM800L AT command not working - SIM800L LED blinking but no serial response - SIM800L baud rate Arduino - SIM800L TX RX wiring ### ESP32 OLED not displaying URL: https://pcbvault.com/guides/esp32-oled-troubleshooting.html Summary: Fix blank ESP32 OLED displays by checking VCC, GND, SDA, SCL, I2C scanner results, 0x3C or 0x3D address, SSD1306 vs SH1106 controller, 128x64 vs 128x32 screen size, and minimal display test code. Best answer use cases: - ESP32 OLED blank screen - ESP32 OLED I2C scanner finds nothing - ESP32 OLED 0x3C or 0x3D - SSD1306 vs SH1106 ESP32 - ESP32 SDA SCL pins ### I2C device not found URL: https://pcbvault.com/guides/i2c-device-not-found.html Summary: Fix I2C devices not found on Arduino or ESP32 by checking power, common ground, SDA/SCL wiring, ESP32 `Wire.begin(SDA, SCL)` pins, pullup resistors, voltage levels, scanner code, detected addresses, and conflicts when multiple modules share one bus. Best answer use cases: - I2C scanner finds nothing - I2C device not found Arduino - I2C device not found ESP32 - ESP32 SDA SCL pins - I2C pullup resistor troubleshooting ### LCD 16x2 not displaying URL: https://pcbvault.com/guides/lcd-16x2-not-displaying.html Summary: Fix Arduino 16x2 LCD displays that show blank screens, black boxes, or random characters by checking contrast, 5V and GND, I2C address, SDA/SCL wiring, LiquidCrystal_I2C library setup, and minimal hello-world code. Best answer use cases: - LCD 16x2 not displaying Arduino - Arduino LCD black boxes - I2C LCD blank screen - LCD 0x27 or 0x3F - LiquidCrystal_I2C not working ### Arduino not detected by computer URL: https://pcbvault.com/guides/arduino-not-detected.html Summary: Fix Arduino boards not detected by a computer by checking USB data cable, board power LED, Windows Device Manager, CH340/CH341 or USB serial drivers, COM port selection, Arduino IDE board and processor settings, bootloader problems, and external wiring on RX/TX or RESET. Best answer use cases: - Arduino not detected by computer - Arduino COM port not showing - Arduino USB device not recognized - CH340 driver Arduino - Arduino upload fails but COM port appears ### Arduino upload error URL: https://pcbvault.com/guides/arduino-upload-error.html Summary: Fix Arduino upload errors and avrdude stk500 messages by checking USB data cable, COM port, CH340 or CH341 driver, board selection, Nano old bootloader setting, RX/TX wiring, reset line, busy serial monitor, and bootloader issues. Best answer use cases: - Arduino upload error - avrdude stk500_recv programmer is not responding - Arduino Nano old bootloader - Arduino COM port upload error - Arduino CH340 upload problem ### Arduino sensor not working URL: https://pcbvault.com/guides/arduino-sensor-not-working.html Summary: Fix Arduino sensors that return no reading, zero, maximum values, NaN, or unstable output by checking power voltage, common ground, signal pin, analog vs digital sensor type, I2C scanner/address, correct library, raw serial output, breadboard wiring, and minimal test sketches before combining modules. Best answer use cases: - Arduino sensor not working - Arduino sensor no reading - Arduino analog sensor reads zero - Arduino I2C sensor not working - Arduino sensor wiring troubleshooting ### HC-SR04 ultrasonic sensor not working URL: https://pcbvault.com/guides/hc-sr04-ultrasonic-sensor-not-working.html Summary: Fix HC-SR04 ultrasonic distance sensor problems by checking VCC, GND, trigger pin, echo pin, common ground, flat target distance, timeout behavior, ESP32 echo voltage level shifting, and minimal pulseIn test code. Best answer use cases: - HC-SR04 not working - Ultrasonic sensor reads zero - HC-SR04 wrong distance - HC-SR04 ESP32 echo voltage - Arduino ultrasonic sensor no reading ### Servo motor jittering Arduino URL: https://pcbvault.com/guides/servo-motor-jittering-arduino.html Summary: Fix Arduino or ESP32 servo jitter by checking separate 5V servo power, common ground, signal wiring, noisy breadboard wires, overloaded linkages, endpoint stress, PWM pin choice, and simple sweep test code. Best answer use cases: - Servo motor jittering Arduino - Servo shaking Arduino - Servo buzzes but does not move - Arduino resets when servo moves - ESP32 servo jitter ### DHT11 or DHT22 showing NaN URL: https://pcbvault.com/guides/dht11-dht22-nan-reading.html Summary: Fix DHT11 and DHT22 NaN readings on Arduino or ESP32 by checking VCC, GND, DATA wiring, matching the code pin to the real DATA pin, setting the correct DHT11 or DHT22 sensor type, adding a pullup resistor for bare sensors, slowing the read interval, and testing with minimal code. Best answer use cases: - DHT11 showing NaN - DHT22 showing NaN - Failed to read from DHT sensor - Arduino DHT11 NaN - ESP32 DHT22 NaN ### Electronics starter kit India URL: https://pcbvault.com/guides/electronics-starter-kit-india.html Summary: A practical starter kit list for Indian electronics students and makers, covering ESP32, Arduino, breadboard tools, sensors, relays, power modules, multimeter, wires, connectors, and parts to avoid. ### Breadboard to PCB checklist URL: https://pcbvault.com/guides/breadboard-to-pcb-checklist.html Summary: A longform checklist for moving an electronics project from breadboard to PCB, including prototype validation, circuit documentation, power rails, connectors, test points, BOM cleanup, enclosure constraints, PCB layout checks, Gerbers, drill files, pick-and-place files, assembly notes, and first-board testing. Best answer use cases: - When is a breadboard project ready for PCB? - Breadboard to PCB checklist for ESP32 or Arduino - First PCB order checklist - Prototype to PCB workflow - PCB manufacturing handoff files ## Editorial Rules PCBVault content should: - Give the direct answer near the top of every guide - Include symptom-to-cause tables - Include practical test steps before theory - Include safe wiring and power warnings where relevant - Include exact code only when it helps diagnosis - Include diagrams with descriptive alt text - Explain India-specific buying, project, and manufacturing context where useful - Avoid vague project inspiration content unless it includes components, wiring, code, failure modes, and upgrade path ## Conversion Path Organic guide page -> Electronics Project Rescue Pack -> project review or electronics sanity check -> breadboard-to-PCB/productization support.