Dell ST2320LF 23 inch - no power

Dell 2320Lf 23' display, no power issue, a quick check found out 2 diodes possibly short circuit.

Either diode D854 or D855 or both

Original parts = SR520, try to replace with equivalent part or higher, I replace with SB560 from old power supply board

w5500 Ethernet Module with Arduino Mega 2560

This W5500 ethernet module available at Lazada for less than USD6

Just search for W5500

Connect through SPI

7 connections needed from the ethernet module

(5V, GND, MISO, MOSI, SCK, RST & SS) to Arduino Mega 2560

Arduino Mega 2560 pinout

Connection in action

Get an example code from https://www.arduino.cc/en/Reference/Ethernet

Make sure to compile with Ethernet2.h because this module is using W5500 chip

End result, it works!

DIY Myvi - YI Dashcam Installation

Mount the dash-cam accordingly. Tuck in the usb cable in the headliner until you reach the corner panel.



Pop up the corner panel. Careful not to break the panel clips. The are 5 of them.





Run down the cable following the existing cable through an opening just beside the dashboard speaker.



And it should come out somewhere here, behind the dashboard drawer.



Properly lay the cable behind the dashboard drawer to access the cigarette socket and plug in the USB 5V adapter.



Later on I'm planning to get one of these, fuse tap, hard-wire it to the fuse-box through female cigarette socket.





There are still empty spare slots there that we can hook it in.

Arduino - Cheap/Poor Man's CT Sensor

There are several references on how to do this such as;

• CT sensors - Interfacing with an Arduino
• How to build an Arduino energy monitor - measuring mains current only.

For my case, I would like to try it first before start buying a CT sensor.
So I come out with below idea, using toroid inductor/coil for testing.

Live wire 240VAC going through the toroid.
Please take precautionary steps with this.

Arduino and sensor board setup

#include "EmonLib.h"                   // Include Emon Library
EnergyMonitor emon1;                   // Create an instance

void setup()
{  
    Serial.begin(9600);
    emon1.current(1, 500);             // Current: input pin, calibration.
}

void loop()
{
    double Irms = emon1.calcIrms(2000);  // Calculate Irms only
    Serial.println(Irms);          // Irms
}

Arduino sketch - quick copy/paste code

Hook it up and testing. It will not be accurate, just to get an idea on how it works.

IBM 9512-AB1 TFT Monitor 715A917-1-4 Backlight Inverter Fix

Symptom, no backlight, but the LCD it self is OK.

Inverter board (left) and main board (right).

Inverter board close up.

From my observation, this board will works when hot but not when cold.

A lot of try and error to trace this but finally, found the culprit.

This cap value determine the 5001C PWM controller short circuit protection timing. As mentioned in the 5001C PWM controller datasheet, the timing must be much longer (generally 10 to 15 times) than the converter start-up period or the converter will not start.

Replace with Aluminum caps for testing...

Put it back in...

There you go :-)

Replacing Haier L32A16 Backlight To LED

Before...

Get a white LED strip. 5 meters = USD7

Mount it...

 End result...

Noxxa Multifunction Pressure Cooker - No Power

Just to share how to fix Noxxa Multifunction Pressure Cooker no power issue.

Symptom: The front panel didn't light up. So let's open it.

Start check the simple things first, temperature fuse continuity? OK, any swollen capacitors? nope!

Next, power it up and check is there any output before (AC) and after the bridge (DC)? YES.

Regulator (7805) output? NO! Found it. Input is about 14V but no output

This is the power supply for the front panel circuit board.

 Desolder it out an do a quick test by it an 12v input

No output at all, compare with the new one

Put it back together again, plus a heat sink to the 7805 regulator. This might prevent it from overheating again, I hope so.

 

Finallly :-)

Samsung SyncMaster 732NW Power Supply Modification

A Samsung SyncMaster 732NW Monitor came in last 3 weeks into my workshop after getting struck by lightning. This is what happen to the power supply board.

A bad capacitor, several diodes shorted, a blown fuse and blown SMPS Power Switch. Luckily the digital board, LCD and back-light still OK.

This is the heart of SMPS, the chopper (PWM) controller with built-in SenseFET by Fairchild.

Too many parts need to be replaced. So here is the shortcut. :-)

From the schematic diagram, we can see that it requires 2 types of power sources, 15VDC and 5.1VDC. Desktop power supply will do the job. It can supply 12VDC and 5VDC. Lower but tested working fine. 5VDC for the digital board and 12VDC for the back-light inverter.

A quick modification using 4-pin peripheral power connector. Several bulky components removed from the heavily damaged primary section.

There you go...