Technical description and composition of the PANASONIC TX-LR37U20 TV, panel type and modules used. The composition of the modules.PANASONIC
Model: TX-LR37U20
Chassis / Version: KM09
Panel: AX094F072G
PWM Inverter: STR-H7204, STR-H3475
MOSFET Inverter: K6A55DA
Power Supply (PSU): TNP4G470
PWM Power: STRA6059 (Stb), FA5501A (PFC), SSC6200
MainBoard: TNP4G468 1 A A00949VP
IC MainBoard: H27U1G8F2BTR, 24C32, LV4921, R2A11014AFT, BD8365KV, BU8364KV
Tuner: ENG37F03KF
Control: IR: TNPA4834
TX-LR37U20 Specifications
PANASONIC TX-LR37U20
General recommendations for TV LCD repair
Possible malfunctions
- The PANASONIC TX-LR37U20 does not turn on, the indicators on the front panel do not light or flash. The TV does not respond to the control buttons and the remote control.
In such cases, the fault should be looked for primarily in the TNP4G470 power supply module. It is necessary to measure its output voltages, and in the event of their absence (full or partial), the serviceability of the power switches of the converters and rectifier diodes should be checked for a possible short circuit.
In case of breakdowns in the secondary circuits of the converter, it can usually work in an emergency mode in a short-circuit mode, and with a short circuit in the power elements of the primary circuit, the mains fuse or current sensor in the source of the key most often breaks off.
Mos-Fet keys used in switching power supplies usually fail due to a malfunction of other elements, which can disable it in key mode, or provoke an excess of the maximum current or voltage values. These can be circuits supplying a PWM controller, damper or frequency setting circuits, or OOS (negative feedback) elements in the stabilization circuit. PWM controllers (PWM) STRA6059 (Stb), FA5501A (PFC), SSC6200, in the absence of external damage and short circuit between the terminals, are checked by replacing them with known good ones.
- There is no picture, there is sound, it reacts to the remote control, the channels are switched. In some cases, the image appears when turned on and disappears immediately.
A defect can be caused by problems in the nodes or elements of the display backlight, or in the power supply of lamps or the inverter.After checking all the electrolytic capacitors of the filters that are involved in the power supply of the inverter, ring the power switches in its converter for breakdown and the secondary windings of transformers for an open circuit.
Sometimes it is necessary to disable the inverter protection for diagnostic purposes. In such cases, special care must be taken during work, and the protective circuits must be restored immediately after the repair is completed.
- The indicator blinks or is on constantly, the TV does not turn on, does not respond to the remote control.
Repair or diagnostics of the TNP4G468 motherboard should begin with checking the stabilizers and power converters necessary to power the microcircuits and the matrix. If necessary, you should update or replace the software (software). Complicated repair of MB (SSB) board is in some cases possible and practiced by repairmen. To do this, check and, if necessary, replace the elements H27U1G8F2BTR, 24C32, LV4921, R2A11014AFT, BD8365KV, BU8364KV. BGA chip faults are usually easy to detect by warm-up.
A malfunction of the ENG37F03KF tuner is established after checking the software and all supply voltages at its terminals. The data exchange of the tuner with the processor via the I2C bus can be monitored with an oscilloscope.
Once again, we remind TV users: do not try to repair yourself without the appropriate knowledge, experience and the necessary qualifications! Trust the repair to professionals with sufficient experience in the field of electronic repair.
DOWNLOAD SCHEMATIC DIAGRAM / SERVICE MANUAL ------------------> PANASONIC TX-LR37U20 Chassis KM09 PANASONIC TX-LR37U20
MainBoard TNP4G468 is shown in the figure below:TNP4G468
External view of the power supply
The main features of the PANASONIC TX-LR37U20 device:
Installed matrix (LCD panel) AX094F072G.
A converter controlled by the STR-H7204, STR-H3475 PWM controller is used to power the backlight lamps. Keys of type K6A55DA are used as power elements of the inverter.
The formation of the necessary supply voltages for all nodes of the PANASONIC TX-LR37U20 TV is carried out by the TNP4G470 power module, or its analogs using STRA6059 (Stb), FA5501A (PFC), SSC6200 microcircuits.
MainBoard - the main board (motherboard) is a TNP4G468 module using the H27U1G8F2BTR, 24C32, LV4921, R2A11014AFT, BD8365KV, BU8364KV and others.
The ENG37F03KF tuner provides reception of television programs and tuning to channels.
PANASONIC TX-LR37U20 TV with LCD AX094F072G, 37 "(94 cm) in 16: 9 format. Dynamic contrast ratio of 20,000: 1 is provided by a special control of the backlight depending on the illumination of areas in the scene.
The AX094F072G panel and TNP4G468 motherboard firmware provide HD and Full HD viewing at 1920x1080 pixels in 1080p (Full HD) graphics. The input analog video signal can be processed in PAL, SECAM, NTSC systems. Graphic processing and formation of a digital signal picture occurs in the standards 480i, 480p, 576i, 576p, 720p, 1080i, 1080p. Multimedia file formats supported by the video processor: MP3, MPEG4, JPEG.
The power of the acoustic audio system is 20 W (2x10 W), provided by two speakers. Uses NICAM stereo signal system and Sound Surround function.
External interface (communication with other devices) is supported by standard input and output connectors: antenna input (RF), AV x2, audio x3, component, VGA, HDMI x3, USB. A headphone output is provided for individual listening. To connect a computer or laptop, a VGA (D-Sub 15) connector is used that supports resolutions: 640x480, 800x600, 1024x768, 1280x1024, 1360x768.
The digital tuner is capable of receiving terrestrial and cable channels in DVB-T standards.
Dimensions: with stand 915x620x287 mm, without stand 915x577x97 mm.
TV weight: with stand: 15 kg, without stand: 13 kg.
Attention! The AX094F072G panel of the PANASONIC TX-LR37U20 LCD TV is a rather expensive component.
Avoid impacts on the glass and pressure on the screen surface to avoid irreversible damage to the LCD panel!