REPAIRING AND NOT THROWING AWAY

REPAIRING AND NOT THROWING AWAY

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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Friday 14 February 2020

REPAIR / SERVICING TV LG 27MT58VF-PZ

Technical description and composition of the LG 27MT58VF-PZ TV, panel type and applicable modules. The composition of the modules.
LG LED
Model: 27MT58VF-PZ
Chassis / Version: LD60A
Panel: HC270EUN-SLDP1-41XX
LED driver (backlight): integrated into MainBoard
PWM LED driver: MP3378E
Power Supply (PSU): Adapter 19V
MainBoard: EAX66873503 (1.2) EBT64207103
IC MainBoard: CPU: LGE6351, Audio: M28720, SPI FLASH: 25L8005, Eeprom: 4G25 (24C256)
Tuner: TDJA-G301D
Specifications 27MT58VF-PZ
LG 27MT58VF-PZ
General repair guidelines for TV LCD LED
Possible malfunctions
- The LG 27MT58VF-PZ TV does not turn on and does not show any signs of operability at all. There is no reaction to the remote control and control buttons from the front panel.
Typically, with such manifestations, the defect is caused by faulty elements in the main power supply adapter.
This TV model is equipped with an external power adapter type Adapter 19V, which the owner can purchase independently, and repairing it may not always be advisable, however, sometimes there is a certain sense to open it and eliminate simple typical defects typical of IPS. It is necessary to measure its output voltages, and in case of their absence, check the operability of the power switches of the converters and rectifier diodes for the probability of a short circuit.
In case of any breakdowns in the secondary circuits, the converter can operate in emergency short circuit mode, and during short circuit in the power elements of the primary circuit, the mains fuse or the current sensor at the source of the key more often breaks.
Mos-Fet power switches, used in switching power supplies, sometimes fail due to a malfunction of any other elements that can put it out of operation in key mode or create an excess of the maximum permissible parameters of the switch. These can be elements supplying the PWM controller, frequency-setting or damping circuits, or negative feedback elements in the stabilization circuit. PWM controllers, in the absence of visible damage or frank short-circuit between the terminals, are checked by replacing with new, or obviously working.
- There is no image, but there is sound, it reacts to the remote control. Or the image appears when you turn it on and immediately disappears
In such cases, the most likely malfunction of the LED backlight elements. The reason for this may be a break in the LED circuit, or a problem in stabilizing their power supply.
To check the health in the LED circuit, it is better to use a current source with a maximum voltage of 200V. We do not recommend using any voltage sources for this purpose. You can check each LED individually with a simple Chinese multimeter (powered by 9 volts) in the P-N-junction test mode. If you connect the red probe of the multimeter to the anode of the LED, and the black to its cathode, then the 3-volt LED will light up slightly, and in the opposite direction you can detect the transition of the emergency zener diode. A zener diode PN junction indirectly indicates a LED-a
- The TV does not turn on, does not respond to the remote control. The indicator blinks or signals standby mode.
Repair or diagnostics of the EAX66873503 motherboard should begin by checking the stabilizers and power converters needed to power the chips and matrix. If necessary, update or replace the software (software). If it is not possible to replace the MB (SSB) board, you need to check the health of its elements - CPU: LGE6351, Audio: M28720, SPI FLASH: 25L8005, Eeprom: 4G25 (24C256). Defective components should be replaced.
Before changing the tuner TDJA-G301D, if it is not possible to tune to television channels, make sure that there are supply voltages, which must be measured at the corresponding terminals of the tuner and checked for correctness. The pulses of the data exchange of the tuner with the processor can be controlled by an oscilloscope
TV users and owners need to remember that attempts to self-repair a LG 27MT58VF-PZ TV without the appropriate qualifications and necessary experience can lead to serious negative consequences!

To reduce the backlight current in LED drivers with the MP3378E PWM controller, it is necessary to proportionally increase the total resistance of the resistors from pin 3 (RISET) to the chassis. Calculation of current in milliamperes and resistance in kilo-ohms 977 / Rset for each channel. Parallel channels are summed. For example, for four parallel channels and a RISET 10 KOhm resistance, the total current will be 97.7 * 4 = 391 mA.

More details on this page


 The appearance of the MainBoard EAX66873503 is shown in the figure below:
EAX66873503
EAX66873503 can be used in TVs:
LG 22LH450V PZ (Panel HM215EUN-SLMP1 - 41XX), LG 24LH450U (Panel V236BJ1-LE2A), LG 28LH451U (Panel HC275EXN-ABVP1-41XX), LG 20MT48VF 20MT48VF-PZ (Panel 1366x768 720p HD).
Main features of the device LG 27MT58VF-PZ:
Installed matrix (LED-panel) HC270EUN-SLDP1-41XX.
To power the backlight LEDs, a converter is used, combined with the main board EAX66873503, controlled by the MP3378E PWM controller.
To power all the internal components of the LG 27MT58VF-PZ TV, an external adapter 19V type source is used.
MainBoard - the main board (motherboard) is an EAX66873503 module using CPU chips: LGE6351, Audio: M28720, SPI FLASH: 25L8005, Eeprom: 4G25 (24C256) and others.
The TDJA-G301D tuner provides TV reception and channel tuning.
Posted By: FRANK at 02:15
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