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 28 February 2020

REPAIR / SERVICING TV LG 42LN548C

Technical description and composition of the LG 42LN548C TV, panel type and applicable modules. The composition of the modules.
LG LED
Model: 42LN548C
Chassis / Version: LD31B / LD36B
Panel: LC420DUE (SF) (R1)
LED backlight: 6916L-1215A 6916L-1216A 6916L-1217A 6916A-1214A
T-CON: 6870C-0452A
LED driver (backlight): integrated into PSU
PWM LED driver: MAP3202 (MAP3202SIRH)
MOSFET LED driver: FDT86106, STF10NM60N
Power Supply (PSU): EAX64905301 2.4 LGP42-13PLI
PWM Power: SSC1S311A (PWM flyback), NR891D
MOSFET Power: MDF11N65B
MainBoard: EAX65120904 (1.0) EBR77208203
IC MainBoard: LGE2111A-T8, STA3808WF
Tuner: TDSS-G101D
Specifications 42LN548C
LG 42LN548C
General repair guidelines for TV LCD LED
Possible malfunctions
- The LG 42LN548C TV does not turn on, does not respond to the remote control and the control panel buttons, the indicators do not light up and do not blink.
Failure in such cases should begin to be sought in the EAX64905301 power supply circuits. It is necessary to measure its output voltages, and if they are absent, check the operability of the power switches (MDF11N65B) of the converters and rectifier diodes for a short circuit probability.
In case of diode breakdowns in the secondary circuits, the converter can operate in emergency short-circuit mode without output voltages, and during short circuit in the power elements of the primary circuit, the mains fuse and / or current sensor at the source of the key usually breaks.
Breakdown of power switches (MosFet) in pulsed sources is sometimes caused by malfunctions of other circuit elements, for example, in circuits supplying a PWM controller, frequency-setting or damper ones, as well as in negative feedback (OOS) stabilization circuits. PWM controllers (PWM) SSC1S311A (PWM flyback), NR891D, if they do not have visible damage to the case and open fault between the terminals, are usually checked by replacement.
- There is no image, but there is sound and reaction to the remote control. Or for a second, the image may appear immediately after switching on.
A malfunction is usually most likely in these cases at the backlight nodes of the display matrix. 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 indicator blinks or lights constantly, the TV does not turn on, does not respond to the remote control.
Repair or diagnostics of the EAX65120904 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). In some cases, to repair the MB board (SSB), it may be necessary to replace the chips - LGE2111A-T8, STA3808WF with new or obviously working ones. In cases where BGA technologies are used, defects are usually localized by the heating method.
If there is no reception of television channels, but the TV is working properly from external devices, first of all you need to check the power supply of the TDSS-G101D tuner and update the software. The pulses from the I2C bus must be controlled with an oscilloscope.
Attention to users! Self-repair of the LG 42LN548C TV without the appropriate qualifications and necessary experience can lead to its complete non-repairability!
 SCHEMATIC DIAGRAM ---------->  LG 42LN54** 42LN54**-Z* Chassis LD31B/LD36B.

  SCHEMATIC DIAGRAM ---------->  LG 37/39/42 Inch LGP3739-13PL1, LGP42-13PL1


 The appearance of the MainBoard EAX65120904 is shown in the figure below:
EAX65120904
The appearance of the power supply
Main features of the device LG 42LN548C:
Installed matrix (LED-panel) LC420DUE (SF) (R1).
The matrix control uses the Timing Controller (T-CON) 6870С-0452A.
To power the backlight LEDs, a converter is used, combined with a power supply unit, controlled by the MAP3202 PWM controller (MAP3202SIRH). As the power elements of the LED driver, keys of the type FDT86106, STF10NM60N are used.
The necessary supply voltages for all nodes of the LG 42LN548C TV are generated by the EAX64905301 power module, or its analogs using SSC1S311A (PWM flyback), NR891D microchips and MDF11N65B type power switches.
MainBoard - the main board (motherboard) is an EAX65120904 module, using LGE2111A-T8 chips, STA3808WF and others.
The TDSS-G101D tuner provides TV reception and channel tuning.
Additional technical information about the panel:
Brand: LG Display
Model: LC420DUE-SFR1
Type: a-Si TFT-LCD, Panel
Diagonal size: 42 inch
Resolution: 1920x1080, FHD
Display Mode: IPS, Normally Black, Transmissive
Active Area: 927.94x521.96 mm
Surface: Antiglare (Haze 1%), Hard coating (3H)
Brightness: 300 cd / m²
Contrast Ratio: 1200: 1
Display Colors: 16.7M (8-bit), CIE1931 68%
Response Time: 6/9 (Tr / Td)
Frequency: 60Hz
Lamp Type: 2 strings WLED Without Driver
Signal Interface: LVDS (2 ch, 8-bit), 51 pins
Voltage: 12.0V
Posted By: FRANK at 06:38
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