Master Electronics Repair !

Welcome to Master Electronics Repair! website.Here you will find:Service Modes, Circuit Diagrams,Service manuals, Firmware Update procedure, Disassemble procedure, Universal remote control setup codes, Troubleshooting, Diagnosing, Measuring, and more.... of many of LCD/LED TV/Displays,others various electronic apparates,trough many technical notes and tips/tricks to help repairing/fixing Troubles/ faults,for electrical technicians.This site helps you to save the Earth from electronic waste!

Richtige Fernseher haben Röhren!

Richtige Fernseher haben Röhren!

In Brief: On this site you will find pictures and technical information about Service Modes, Circuit Diagrams, Firmware Update procedure, Disassemble procedure, Universal remote control set-up codes, Troubleshooting and more....

If you go into the profession, you will obtain or have access to a variety of tech tips databases HERE IT IS Master Electronics Repair !.

These are an excellent investment where the saying: 'time-is-money' rules. However, to learn, you need to develop a general troubleshooting approach - a logical, methodical, method of narrowing down the problem. A tech tip database might suggest: 'Replace C536' for a particular symptom. This is good advice for a specific problem on one model. However, what you really want to understand is why C536 was the cause and how to pinpoint the culprit in general even if you don't have a service manual or schematic and your tech tip database doesn't have an entry for your sick TV or VCR.

While schematics are nice, you won't always have them or be able to justify the purchase for a one-of repair. Therefore, in many cases, some reverse engineering will be necessary. The time will be well spent since even if you don't see another instance of the same model in your entire lifetime, you will have learned something in the process that can be applied to other equipment problems.
As always, when you get stuck, checking out a tech-tips database may quickly identify your problem and solution.In that case, you can greatly simplify your troubleshooting or at least confirm a diagnosis before ordering parts.

Happy repairing!

Today, the West is headed for the abyss. For the ultimate fate of our disposable society is for that society itself to be disposed of. And this will happen sooner, rather than later.

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..............The bitterness of poor quality is remembered long after the sweetness of todays funny gadgets low price has faded from memory........ . . . . . .....
Don't forget the past, the end of the world is upon us! Pretty soon it will all turn to dust!

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Thursday, 7 March 2019

SHARP LC-42DH77E SERVICE MODE TROUBLESHOOTING AND POWER SUPPLY CIRCUIT DIAGRAM – LCD TELEVISION REPAIR

SHARP LC-42DH77E Service mode troubleshooting and power supply circuit diagram – LCD television repair

Category: LCD Television Repair

Contents of this article

How to access service mode
Troubleshooting
24V Power supply circuit diagram

SHARP LC-42DH77E

SERVICE MODE

HOW TO ENTER TO SERVICE MODE
In order to reach service menu, First Press “MENU” Then press the remote control code two times, which is “4725”.

SOFTWARE UPDATE

Analog - Digital SW update via USB

1. Please copy the files to USB (root).
# mb60_en.bin
# mboot.bin
# usb_auto_update.txt
2. Turn power to OFF by mechanical switch(rocker switch) or removing AC plug. And plug the USB to TV
3. Keep pressing OK key from remote controller and then turn the TV power to ON(by mechanical switch or by inserting the AC plug) and keep OK key pressed until the stanby led blinks rapidly(rapid blinking is faster than normal blinking)
4. When the led is started to blink rapidly, you can release the OK key.Please wait approximately for 1-2 minutes.
5. When the blinks of led is stopped, TV opens autamatically with the new SW.

TROUBLESHOOTING

No Backlight Problem
Problem: If TV is working, led is normal and there is no picture and backlight on the panel.
Possible causes: Backlight pin, dimming pin, backlight supply, stby on/off pin Backlight pin should be high in open position. If it is low, please check Q181 and panel cables.

Dimming pin should be high or square wave in open position. If it is low, please check S16 for Mstar side and panel or power cables, connectors.

Backlight power supply should be in panel specs. Please check CN705 for MB60, related connectors for power supply cards.

STBY_ON/OFF should be low for standby on condition, please check R1677.

CI Module Problem
Problem: CI is not working when CI module inserted.
Possible causes: Supply, supply control pin, detect pins, mechanical positions of pins CI supply should be 5V when CI module inserted. If it is not 5V please check CI_POWER_CTRL, this pin should be low.

Please check mechanical positions of CI module.
Detect ports should be low. If it is not low please check CI connector pins, CI module pins and 3V3_VCC on MB60.

Led Blinking Problem
Problem: LED blinking, no other operation
This problem indicates a short on Vcc voltages. Protect pin should be logic high while normal operation. When there is a short circuit protect pin will be logic low. If you detect logic low on protect pin, unplug the TV set and control voltage points with a multimeter to find the shorted voltage to ground.

IR Problem
Problem: LED or IR not working
Check LED card supply on MB60 chassis.

Keypad Touchpad Problems
Problem: Keypad or Touchpad is not working
Check keypad supply and KEYBOARD pin on MB60.

USB Problems
Problem: USB is not working or no USB Detection.
Check USB Supply, It should be nearly 5V. Also USB Enable should be logic high.

No Sound Problem
Problem: No audio at main TV speaker outputs.
Check supply voltages of VDD_AUDIO, 5V_VCC and 3V3_VCC with a voltage-meter.
There may be a problem in headphone connector or headphone detect circuit (when headphone is
connected, speakers are automatically muted). Measure voltage at HP_DETECT pin, it should be 3.3v.

No Sound Problem at Headphone
Problem: No audio at headphone output.
Check HP detect pin, when headphone is. Check 5V_VCC and 3V3_VCC with a voltage-meter.

Standby On/Off Problem
Problem: Device cannot boot, TV hangs in standby mode.
There may be a problem about power supply. Check 12V_VCC, 5V_VCC and 3V3_VCC with a voltagemeter. Also there may be a problem about SW. Try to update TV with latest SW. Additionally it is good to check SW printouts via hyper-terminal (or Teraterm). These printouts may give a clue about the problem.

No Signal Problem
Problem: No signal in TV mode.
Check tuner supply voltage; 5V_TUN. Check tuner options are correctly set in Service menu. Check AGC voltage at RF_AGC pin of tuner.

NCP1392B -High-Voltage Half-Bridge Driver

The NCP1392B/D is a self−oscillating high voltage MOSFET driver primarily tailored for the applications using half bridge topology. Due to its proprietary high−voltage technology, the driver accepts bulk voltages up to 600 V. Operating frequency of the driver can be adjusted from 25 kHz to 480 kHz using a single resistor. Adjustable Brown−out protection assures correct bulk voltage operating range. An internal 100 ms or 12.6 ms PFC delay timer guarantee that the main downstream converter will be turned on in the time the bulk voltage is fully stabilized. The device provides fixed dead time which helps lowering the shoot−through current.

PIN CONFIGRATION OF NCP1392

Pin #	Pin Name	Pin Description
1	VCC	The driver accepts up to 16 V (given by internal zener clamp)
2	Rt	Connecting a resistor between this pin and GND, sets the operating frequency
3	BO	Detects low input voltage conditions. When brought above Vref_EN, it stops the driver. Operation is restored (without any delay) when BO pin voltage drops 100 mV below Vref_EN.
4	GND
5	Mlower	Drives the lower side MOSFET
6	HB	Connects to the half−bridge output
7	Mupper	Drives the higher side MOSFET
8	Vboot	The floating supply terminal for the upper stage

POWER SUPPLY BOARD SCHEMATIC DIAGRAM

CLICK ON THE IMAGE TO ZOOM IN