Tuesday, 31 March 2020

REPAIR / SERVICING TV TOSHIBA 42AV502PR

Technical description and composition of the TOSHIBA 42AV502PR TV, type of panel and applicable modules. The composition of the modules.
Toshiba
Model: 42AV502PR
Panel: LC420WXN-SAB1
T-CON: 75013100
Inverter (backlight): 75013089
Mainboard: PE0484
IC MainBoard: TDA8891 TDA15451 LPC924F TL2417
Tuner: TAEA-G081D
Specifications 42AV502PR
TOSHIBA 42AV502PR
General recommendations for repairing TV LCD
Any repair of electronic equipment begins with an external inspection of the device and diagnostics of the malfunction. In this case, you should visually carefully examine all the elements of the TOSHIBA 42AV502PR TV, both internal and external. Visible damage to elements can sometimes suggest further directions for finding a defect before starting the necessary measurements. Swollen electrolytic or cermet capacitors, charred resistors, ring cracks in the soldered terminals of the elements - all this can significantly help the master to determine the causes and consequences of the malfunction of the TV.
Malfunctions of the power module can be expressed in different ways, for example, the TOSHIBA 42AV502PR does not turn on at all and the control lamps on its front panel do not light up and do not blink, and there are no signs of operability. It is advisable to start the troubleshooting of the power supply module by checking the mains fuse. If it is torn, it is necessary to check first of all the power semiconductor elements - rectifier diodes and the power switch of the converter, which are often found in a breakdown state in such situations.
It should be remembered that the N-FET keys used in flyback converters rarely fail for no reason that must be sought by checking other elements of the circuit. Often the breakdown is caused by malfunctions of electrolytic capacitors or semiconductor elements in the primary circuit, or by a break in the resistors in the stabilization circuits. The PWM controller chip can also cause a breakdown of the power switch of the converter.
If an active Power Factor Corrector (PFC) is used in the power module circuitry, it is sometimes more difficult to troubleshoot. Knowledge, experience, intuition and skills in such cases have a great advantage for a successful repair.
If the TOSHIBA 42AV502PR does not have an image, there is sound and the channels are switched, there is a possibility of a malfunction of the display backlight, or their power converter - inverter. Sometimes when you turn on the image appears and disappears immediately. In such cases, it is necessary to check the electrolytic capacitors of the power filter of the inverter itself, including in the secondary rectifier of the main PSU.
Diagnostics of the inverter 75013089 can be difficult due to the operation of the protection, which is organized by the designers to prevent negative consequences or fires in emergency cases, for example, during short circuits or breaks in the lamp power supply circuit, as well as their possible depressurization. To make the necessary measurements at control points or to take the necessary waveforms, repairmen have to block the protection circuits in order to be able to diagnose.
In these cases, special care must be taken in view of the risk of failure of the power elements. After completing all repair work, it is imperative to restore the protection circuits for full and safe further operation of the TV by the user.
Attention to users! Independent repair of the TOSHIBA 42AV502PR TV without the appropriate qualifications and experience can lead to its complete non-repairability!

Service Manuals with Schematic Diagrams 84 pages of 2008 on model 37AV502PR, 42AV502PR


SCHEMATIC DIAGRAM  / SERVICE MANUAL   ------------------>    Toshiba 42AV502PR - PE0484, PE0486, PE0643 Service manual and schematic diagram
 The appearance of MainBoard PE0484 is shown in the figure below:
PE0484
PE0484 can be used in TVs:
TOSHIBA 32AV500PR (Panel LC320WXN (SB)(B1)), TOSHIBA 32AV500PSR (Panel LC320WXN (SB)(B1)), TOSHIBA 32AV501PR (Panel LK315T3LA31), TOSHIBA 32AV502PR (Panel LK315T3LA31 (75012574)), TOSHIBA 37AV502PR (Panel LC370WXN(SA)(C2) 75012583), TOSHIBA 42AV500PSR (Panel LC420WXN (SA)(B1)), TOSHIBA 42AV501PR (Panel LC420WX7-SLC1), TOSHIBA 42AV502PR (Panel LC420WXN-SAB1), TOSHIBA 37AV500PR (Panel AX094B002B).
Main features of the TOSHIBA 42AV502PR device:
Installed matrix (LCD panel) LC420WXN-SAB1.
The matrix control uses the Timing Controller (T-CON) 75013100.
An inverter 75013089 is used to power the backlight.
The required supply voltage for all nodes of the TOSHIBA 42AV502PR TV is provided by a switching power supply.
MainBoard - the main board (motherboard) is a PE0484 module, using TDA8891 TDA15451 LPC924F TL2417 chips and others.
The TAEA-G081D tuner provides TV reception and channel tuning.
Additional technical information about the panel:
Brand: LG.Philips LCD
Model: LC420WXN-SAB1
Type: a-Si TFT-LCD, Panel
Diagonal size: 42 inch
Resolution: 1366x768, WXGA
Display Mode: S-IPS, Normally Black, Transmissive
Active Area: 930.25x523.01 mm
Surface: Antiglare (Haze 13%), Hard coating (3H)
Brightness: 500 cd / m²
Contrast Ratio: 1100: 1
Display Colors: 16.7M (8-bit), CIE1931 72%
Response Time: 5 (G to G)
Frequency: 60Hz
Lamp Type: EEFL Embedded (Inverter)
Signal Interface: LVDS (1 ch, 8-bit), 30 pins
Voltage: 12.0V