Thursday, 26 March 2020

REPAIR / SERVICING TV TOSHIBA 19AV500P

Technical description and composition of the TOSHIBA 19AV500P TV, type of panel and applicable modules. The composition of the modules.
Toshiba
Model: 19AV500P
Chassis / Version: VTV-L19102 STM19E
Panel: LTM190M2-L31 REV.40D
Inverter (backlight): STV19 VTV-P1901 REV1
PWM Inverter: OZ9938GN (16)
MOSFET Inverter: P2804ND5G NIKOS (5)
Power Supply (PSU): 75012363 PC BOAD ASSY, POWER, 39C00S51L17
PWM Power: LD7576 (8pin)
MOSFET Power: K4101
MainBoard: VTV-L19102 PC BOARD ASSY, MAIN, 19AV500P, 39C00S51L04
IC MainBoard: MST98981CLD-LF 432A-2CL1 TDA8932BTW
Tuner: FQ1216ME 3139 147 26416
Control: CT-90298
Specifications 19AV500
TOSHIBA 19AV500P
General recommendations for repairing TV LCD
It is advisable to start repairing the TOSHIBA 19AV500P TV with an external examination of all its constituent elements, both internal electronic components and external. Inspection is also subject to body elements, control buttons, screen, connectors and cords. 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. Experienced repairmen are often aware of the causes of the defect and the possible consequences, for example, from ring cracks in the soldering of the leads of the elements, as well as from swollen capacitors or resistors burnt to coal dust and other external indirect signs.
If the TV does not turn on, no indicators on its front panel are lit or blinking. Also, if the TV does not respond to the remote control and buttons, does not make any sounds or any signs of operability when turned on, there is a certain chance that the power supply module 75012363 PC BOAD ASSY, POWER, 39C00S51L17 is faulty and needs repair. Sometimes with similar manifestations a problem can only occur in the absence of processor power, but this happens much less often. If the mains fuse is broken in the power supply, in most cases a breakdown of the power switch K4101 is detected, which can be integrated with the PWM controller, or a separate field-effect transistor can be used. The rectifier bridge diodes and the electrolytic capacitor of the mains rectifier filter should also be checked.
The reasons for the breakdown of the power switch of the flyback converter of the power module can be different, for example, a malfunction of semiconductor cells or electrolytic capacitors in the stabilization circuits of the primary circuit, as well as a failure in the operation of the LD7576PS PWM controller microcircuit or broken resistors in its wiring.
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.
Sometimes the TOSHIBA 19AV500P TV does not have an image, but there is sound, or the image appears and immediately disappears. In this case, there is a high probability of a malfunction of the backlight converter, or of the lamps themselves, which can be checked by replacement. In such cases, it is necessary to verify the serviceability of all electrolytic capacitors of the filter according to the power supply of the inverter itself, including in the power supply unit (power supply unit).
Often, attempts to repair the STV19 VTV-P1901 REV1 inverter are hampered by the fact that the diagnosis of the malfunction is complicated by the operation of its protection, which is designed to turn off the inverter in emergency conditions - when the lamps are depressurized, breaks or short circuits in high-voltage connections and other emergency situations. Lock protection to localize the defect is popular among repairmen.
When diagnosing with the protection off, special precautions must be taken, because there is a risk of failure of the power elements of the inverter. After the diagnosis, it is imperative to restore the protection circuits for the inverter to operate normally.
Repair of the PC BOARD ASSY, MAIN, 19AV500P, 39C00S51L04 // VTV-L19102 motherboard must be started by diagnosing and checking all linear stabilizers or power converters of its microcircuits. Sometimes it may be necessary to update the software (software) - flashing FLASH or EEPROM. Often, the MB (SSB) card must be replaced in case of complex malfunctions that are difficult to detect. When trying to repair, you should check its elements - MST98981CLD-LF 432A-2CL1 TDA8932BTW and replace failed chips with new ones.
In cases where there is no tuning to the local television channels, you should make sure that there is a varicap supply voltage (30-33V) and other supply voltages at the terminals of the FQ1216ME 3139 147 26416 tuner.
Once again, remind users! Attempts to independently repair the TOSHIBA 19AV500P TV without the appropriate qualifications and experience can lead to its complete non-repairability!


SCHEMATIC DIAGRAM  / SERVICE MANUAL   ------------------>    Toshiba 19AV500P

FIRMWARE FOR SPI FLASH  ----------->   TOSHIBA 19AV500P, Main: STM19E VTV-L19102, Panel: LTM190M2-L31
 Service Manual 35 pages of 2008 on models  19AV500PG, 19AV500PR, 19AV500PB, 19AV501PG, 19AV501PR, 26AV500PB, 26AV500PG, 26AV500PR, 19AV505DB, 19AV505DG, 19AV506DB, 19AV506DG, 26AV505DB, 26AV505DG.

 The appearance of the MainBoard VTV-L19102 is shown in the figure below:
VTV-L19102
VTV-L19102 can be used in TVs:
TOSHIBA 19AV500P (Panel LTM190M2-L31 REV.40D), TOSHIBA 19AV501P (Panel LTM190M2-L31).
Main features of the TOSHIBA 19AV500P device:
Installed matrix (LCD panel) LTM190M2-L31 REV.40D.
To power the backlight, an STV19 inverter is used, it is controlled by the OZ9938GN PWM controller (16). As power elements of the inverter, keys of the type P2804ND5G NIKOS (5) are used.
The necessary supply voltages for all nodes of the TOSHIBA 19AV500P TV are generated by the power module 75012363, or its analogs using LD7576 microcircuits (8pin) and power switches of the K4101 type.
MainBoard - the main board (motherboard) is a VTV-L19102 module, using MST98981CLD-LF 432A-2CL1 TDA8932BTW chips and others.
The tuner FQ1216ME 3139 147 26416 provides the reception of television programs and tuning to channels.
Information from an alternative source:
TOSHIBA 19AV500P,
Panel Type (Matrix): LTM190M2-L31
Motherboard: VTV-L19102 REV: 1 / STM19E, MST98981CLD-LF, F25L008A / C7054, 24C32A2GLI, TDA8932BTW, Tuner: 3139 147 22641M FQ1216ME / I H-5
PSU & Invertor: STV19 VTV-P1901 REV: 1, LD7576PS, OZ9938GN, P2804ND5G x2
Remote control: CT-90298
Additional technical information about the panel:
Brand: SAMSUNG
Model: LTM190M2-L31 (Glare)
Type: a-Si TFT-LCD, Panel
Diagonal size: 19.0 inch
Resolution: 1440x900, WXGA +
Display Mode: TN, Normally White, Transmissive
Active Area: 408.24x255.15 mm
Surface: Glare (Haze 0%), Hard coating (2H), Reflection 2.0%
Brightness: 300 cd / m²
Contrast Ratio: 1000: 1
Display Colors: 16.7M (6-bit + Hi-FRC), CIE1931 72%
Response Time: 1.3 / 3.7 (Tr / Td)
Frequency: 60Hz
Lamp Type: 4 pcs CCFL Without Driver
Signal Interface: LVDS (2 ch, 8-bit), 30 pins
Voltage: 5.0V


 TOSHIBA 19AV500 LCD TV with LTM190M2-L31 LCD, 19 "(48 cm) diagonal 16:10. The ratio of maximum brightness to minimum (contrast) is 1000: 1. Dynamic contrast ratio of 8500: 1 is achieved by special control of the backlight It is possible to view images in high quality HD at a resolution of 1440x900 pixels in the standard of graphic decomposition 720p (HD Ready). The input high-frequency or video signal can be processed in analog systems PAL, SECAM, NTSC. Graphic processing and digital signal generation takes place in artah 480i, 480p, 576i, 576p, 720p, 1080i, 1080p.
The power of the sound system 6 W (2x3 W) provide two speakers. The audio processing system NICAM STEREO is used.
The external interface (communication with other devices) is supported by standard input and output connectors: antenna input (RF), component, SCART, RGB, HDMI. An output for connecting headphones is provided. To connect a computer or laptop to this TV model, a VGA (D-Sub 15) connector is used on the TV case, this interface supports resolutions: 640x480, 800x600, 1024x768, 1280x1024, 1360x768.
The power consumed by the TV in the operating mode from the network is 43 watts.
Overall dimensions: with stand 460x393x207 mm, without stand 460x352x73 mm.
TV Weight: with stand: 6.7 kg, without stand: 5.76 kg.
Attention! The LTM190M2-L31 REV.40D panel of the TOSHIBA 19AV500 LCD TV is its most expensive component.
Avoid hitting the glass and exerting pressure on the screen to avoid permanent damage to the LCD panel!