Thursday, 26 March 2020

REPAIR / SERVICING TV TOSHIBA 19AV501P

Technical description and composition of the TOSHIBA 19AV501P TV, type of panel and applicable modules. The composition of the modules.
Toshiba
Model: 19AV501P
Chassis / Version: VTV-L19102 STM19E
Panel: LTM190M2-L31
Inverter (backlight): integrated into PSU
PWM Inverter: OZ9938GN
MOSFET Inverter: P2804ND5G
Power Supply (PSU): 453C0151L11 STV19 VTV-P1901 REV1
PWM Power: LD7576PS
MOSFET Power: K4101
MainBoard: VTV-L19102 STM19E
IC MainBoard: Cpu: MST98981CLD-LF, Spi Flash: F25L008A, Sound: TDA8932BTW
Tuner: FQ1216ME
Control: CT-90298
Specifications 19AV501
TOSHIBA 19AV501P
General recommendations for repairing TV LCD
Like any other TV, TOSHIBA 19AV501P repair is advisable to start with an external examination of the visible changes in the external and internal elements. Any external damage can sometimes prompt the repairman to take further steps to determine the malfunction of the TV and localize 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.
Sometimes the TOSHIBA 19AV501P TV simply does not turn on. No control lights on the front panel are lit or blinking, the TV does not respond to the remote control and does not make any sounds or any signs of life when turned on. The most likely cause of the malfunction is a failure of the common power module 453C0151L11 STV19 VTV-P1901 REV1. In this case, the diagnosis and repair of the common power supply should always be started by checking the mains fuse. When it is broken, it is advisable to check for a breakdown, first of all, all power semiconductor elements of the converter and the diode bridge of the rectifier network, as well as the large electrolytic capacitor of the filter of the rectifier network and the K4101 key transistor.
If a breakdown of the power switch of the flyback converter of the power supply unit is detected, it should be remembered that it does not fail without any reasons that should be sought by checking other elements of the primary circuit - electrolytic capacitors, PWM controller LD7576PS, which can only be checked by replacement, as well as other semiconductor elements (diodes, transistors, zener diodes).
Diagnostics of power modules with a Power Factor Corrector (CMC) is somewhat more complicated and requires a more detailed approach.
If the TOSHIBA 19AV501P 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.
Repair of the inverter 453C0151L11 STV19 VTV-P1901 REV1 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.
It should be remembered that when the protection is turned off, there is always a risk of failure of the power elements of the inverter during diagnosis. After repair, it is necessary to restore all standard converter protection circuits.
Once again, remind users! Attempts to independently repair the TOSHIBA 19AV501P TV without the appropriate qualifications and experience can lead to its complete non-repairability!

SCHEMATIC DIAGRAM  / SERVICE MANUAL   ------------------>    Toshiba 19AV501P

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 19AV501P device:
Installed matrix (LCD panel) LTM190M2-L31.
To power the backlight, a converter is used, combined with a power supply, controlled by the OZ9938GN PWM controller. As power elements of the inverter, keys of the type P2804ND5G are used.
The necessary supply voltages for all nodes of the TOSHIBA 19AV501P TV are generated by the 453C0151L11 power supply module or its analogs using LD7576PS microchips and K4101 type power switches.
MainBoard - the main board (motherboard) is a VTV-L19102 module, using Cpu chips: MST98981CLD-LF, Spi Flash: F25L008A, Sound: TDA8932BTW and others.
The FQ1216ME tuner provides television reception and channel tuning.
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 19AV501 LCD TV with LTM190M2-L31 LCD, 19 "(48 cm) diagonal 16:10 format. 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.
Overall dimensions: with stand 460x393x207 mm, without stand 460x352x73 mm.
TV Weight: with stand: 6.7 kg, without stand: 5.76 kg.
Attention! The TOSHIBA 19AV501 LCD TV panel LTM190M2-L31 is its most expensive component.
Avoid hitting the glass and exerting pressure on the screen to avoid permanent damage to the LCD panel!