Friday, 27 March 2020

REPAIR / SERVICING TV TOSHIBA 32AV500PSR

Technical description and composition of the TOSHIBA 32AV500PSR TV, type of panel and applicable modules. The composition of the modules.
Toshiba
Model: 32AV500PSR
Panel: LC320WXN (SB) (B1) // LK315T3LA31 (75012574)
Inverter (backlight): // 75014093
Power Supply (PSU): PE0531 H
PWM Power: A6169 (8), STR-Z2589, 2A20112 (PFC)
MOSFET Power: P10NK80, 10N60
MainBoard: PE0484 A-1
IC MainBoard: TDA8891H1 / N1B TDA15451HV / N1B00 TDA15451 LPC924F TL2417
Tuner: TAEA-G081D
Specifications 32AV500PR
TOSHIBA 32AV500PSR
General recommendations for repairing TV LCD
Repair of the TOSHIBA 32AV500PSR must begin with the diagnosis of the malfunction and a thorough inspection of its external and internal components, including the case ones. Often, for certain external signs, the repairman can draw some conclusions about the reasons for the failure of certain elements of the circuit even before the necessary measurements are made, which will determine the further algorithm for troubleshooting and localizing the defect. Ring cracks in the soldering of the leads of the heating elements, swollen electrolytic capacitors, a charred paint layer on the resistors - all this for the repairman can be a hint in the assumptions about the causes and consequences of the malfunction.
In the case when the 32AV500PSR does not turn on, does not respond to the remote control and the front panel buttons, does not blink bulbs and does not show any signs of operability, the PE0531 H power supply module is most likely to be defective in this case. When diagnosing and repairing the power supply, first of all, check fuse and if it is broken, the cause must be identified. Often in such cases, an avalanche (thermal) breakdown is detected in the power semiconductor elements of the module - rectifier diodes or power switch P10NK80 10N60.
Power switches in flyback converters fail extremely rarely for no reason and, if they are broken, it is necessary to look for a malfunction in the stabilization circuits by checking electrolytic capacitors, semiconductor devices, and resistors in the primary circuit. The reason may be a malfunction of the PWM controller chip A6169 (8) STR-Z2589 2A20112, which can only be checked by replacing it with a new or obviously working one.
Diagnostics of power modules with a Power Factor Corrector (CMC) is somewhat more complicated and requires a more detailed approach.
If, when you turn on the TV, the image appears and immediately disappears, or is initially absent when you turn on, but there is sound and other functions work, there is a high probability of a malfunction of the inverter (power converter for the backlight). In such cases, the lamps, the inverter and the common power module are subject to verification, in which the electrolytic capacitors of the rectifier filter supplying the inverter should be checked.
Inverter repair // 75014093 can often be somewhat complicated by the use of special protection circuits, which are designed to disconnect it in emergency cases for fire safety when the lamps are depressurized, or short circuits or breaks in high-voltage circuits and connections. Sometimes it becomes necessary for diagnostic purposes to block the protection circuits in order to be able to make the necessary measurements at the control points of the circuit.
In such cases, the risk of failure of the power elements of the inverter is most likely, and special care is required during work, and after their completion, it is necessary to restore the protection circuit for further safe operation of the TV by the owner in normal mode.
Diagnosis and repair of the motherboard PE0484A-1 is carried out by checking the performance of power stabilizers or updating the software (software).
Once again, we remind TV users: you should not make attempts to repair it yourself without the appropriate knowledge, experience and the necessary qualifications! Trust the repair only to professionals with sufficient experience in the field of electronic equipment repair.

SCHEMATIC DIAGRAM  / SERVICE MANUAL   ------------------>    Toshiba 32AV500PR. PE0484 PE0486 PE0531 PE0640



 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).
PSU Advanced
According to the conditions of compliance with modern world standards for household switching power supplies, the PE0531 module provides for the use of the Power Factor Correction unit. The PFC circuit is a flyback converter based on the 2A20112 PWM controller. The reactance of an electrolytic capacitor of a line filter at a frequency of 50-60 Hz is usually not more than 20-30 ohms and its charge directly from the network through open diodes could reach tens of amperes per pulse if no filtering were applied.
As a result of the PFC conversion, an increased voltage on the capacitor (about 380V) cannot directly open the rectifier diodes, on the anode of which the voltage will always be slightly less (about 300V) and then its charging current will always be limited by the elements of the PWM controller. As a result, the envelope of the high-frequency pulses of the consumed current will repeat the shape and phase of the input sinusoidal voltage. The presence of an increased voltage (+ 380V) on the network capacitor indicates the serviceability of the PFC node.
The appearance of the power supply
Key Features of the TOSHIBA 32AV500PSR:
Installed matrix (LCD panel) LC320WXN (SB) (B1) or LK315T3LA31 (75012574).
An inverter is used to power the backlight.
The necessary supply voltages for all nodes of the TOSHIBA 32AV500PSR TV are generated by the PE0531 power module or its analogs using A6169 (8), STR-Z2589, 2A20112 (PFC) microcircuits and power switches of the type P10NK80, 10N60.
MainBoard - the main board (motherboard) is a PE0484 module, using TDA8891H1 / N1B TDA15451HV / N1B00 TDA15451 LPC924F TL2417 and others.
The TAEA-G081D tuner provides TV reception and channel tuning.