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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Thursday 27 February 2020

REPAIR / SERVICING TV LG 42LF550V

Technical description and composition of the LG 42LF550V TV, panel type and applicable modules. The composition of the modules.
LG LED
Model: 42LF550V
Chassis / Version: LD55T
Panel: LC420DUE (MG) (A6)
LED backlight: 6916L-1956A / B - Led LG lnnotek DRT 3.0 42_A / B type Rev01
T-CON: 6870C-0480A
LED driver (backlight): integrated into PSU; 208V 235mA
PWM LED driver: LC5901
Power Supply (PSU): EAX66203001 (1.6) LGP3942D-15CH1
MainBoard: EAX66203805 (1.2), RD59341EUJ
IC MainBoard: LGE2136, 25L8035E
Tuner: TDJM-G301D
Control: IR: EBR78480602
Specifications 42LF550V
LG 42LF550V
General repair guidelines for TV LCD LED
Failures of the power module LGP3942D-15CH1 can be expressed in different ways, for example, LG 42LF550V does not turn on at all and the control lights on its front panel do not light up and do not blink, there are no signs of operability. It is advisable to start the troubleshooting of the power supply module by checking the state of the electrolytic capacitors of the rectifier filters and the mains fuse. Defective capacitors should be replaced. If the mains fuse is broken, it is necessary to check first of all the power semiconductor elements - rectifier diodes and transistors, which are often found in such a state of breakdown.
As a rule, the keys in switching power supplies (SMPS) are reliable enough and rarely fail for no reason to be looked for by checking other components of the circuit - electrolytic capacitors, resistors and semiconductor elements of the primary circuit. The PWM chip is verified by replacing it with a known good one.
If, when you turn on the TV, the image appears and immediately disappears, or is missing initially when you turn on, but the sound has other functions that work, there is a high probability of a malfunction of the display backlight LEDs or the LED driver (power converter for the LC420DUE (MG) panel backlight assembly (A6).
A malfunction in the backlight circuits often occurs due to a break in the power supply circuit of the LED lines of the Led LG lnnotek DRT 3.0 42_A / B type Rev01. In such cases, it is often necessary to disassemble the panel and check the LEDs themselves, the rations of their terminals, as well as the reliability of the connections in the connectors and rations of the terminals.
It is impossible to detect a break in the LED line without disassembling the panel with a simple multimeter. The LEDs are connected in series and to open their transitions, a voltage of several tens of volts is required. Ideally, a current source is suitable for such purposes.
If the motherboard EAX66203805 (1.2), RD59341EUJ is faulty, first of all it is necessary to check all the linear stabilizers and power converters of its chips, and also, if necessary, update the software (software). Sometimes you can check the health of MB only by replacement.
If you suspect a malfunction of the TDJM-G301D tuner, first of all, you need to make sure the software is correct, as well as the presence of the necessary voltage levels at the corresponding terminals of the tuner.
Owners and users of the LG 42LF550V TV must remember that self-repair without special knowledge, skills and qualifications can be fraught with negative consequences that can lead to complete non-repairability of the device!



You can reduce the backlight current in televisions with LGP3942D-15CH1 power supplies (EAX66203001) by increasing the resistance of the current sensor. The nominal current in the LEDs is 250 mA. Current sensor - resistor R816 rated 3 Ohm. If you increase the rating to 4.3 Ohm, the current decreases to 175 mA.


SCHEMATIC DIAGRAM --------->  LG CHASSIS LD55T; 42LF550V, 42LF550V-ZA


 The appearance of the MainBoard EAX66203805 is shown in the figure below:
EAX66203805
EAX66203805 can be used in TVs:
LG 32LF564U (Panel LC320DXE (MG)(A3)), LG 42LF550V (Panel LC420DUE (MG)(A6)), LG 32LF560U ZB (Panel NC320DXN VSBP5 ), LG 42LF560V (Panel LC420DUE (MG)(A3)), LG 32LF562V (Panel NC320DUN-VBBP3 (EAJ63171201)), LG 32LF564V (Panel NC320DUN VBBP3), LG 32LF560V (Panel NC320DUN-VBBP3), LG 49LF620V 49LF620V-ZB (Panel LC490DUE (MG)(P2)), LG 42LF551C (Panel LC420DUE-MGA6).
The appearance of the power supply
Main features of the device LG 42LF550V:
Installed matrix (LED panel) LC420DUE (MG) (A6).
The matrix control uses the Timing Controller (T-CON) 6870C-0480A.
To power the backlight LEDs, a converter is used, combined with the power supply, controlled by the LC5901 PWM controller.
The formation of the necessary supply voltages for all nodes of the LG 42LF550V TV is carried out by the EAX66203001 power module, or its analogues.
MainBoard - the main board (motherboard) is an EAX66203805 module, using LGE2136, 25L8035E chips and others.
The TDJM-G301D tuner provides TV reception and channel tuning.
Additional technical information about the panel:
Brand: LG Display
Model: LC420DUE-MGA6
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 (G to G)
Frequency: 60Hz
Lamp Type: WLED Without Driver
Signal Interface: LVDS (2 ch, 8-bit), 51 pins
Voltage: 12.0V
Posted By: FRANK at 06:04
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