Friday 14 August 2020

REPAIRING / SERVICING TV ROLSEN RL-37B05F

Technical description and composition of the ROLSEN RL-37B05F TV, panel type and modules used. The composition of the modules.
ROLSEN LED
Model: RL-37B05F
Chassis / Version: MST6M48 / MST6M182
Panel: LC370WUN (SC) (A1)
T-CON: 6870C-0310A LC420WUN-SCA1
LED driver (backlight): 6632L-0618A, KLS-EE37ARF14 (A) REV: 0.5
PWM LED driver: BD9215AFV, AS324M-E1, KIA78M05F
Power Supply (PSU): K-190N1 REV: A01 465-01A3-19001G
PWM Power: 1653A (PFC), MCP1396AG (16pin), A7350M (8pin)
MOSFET Power: TF20N60, K2645, F3NK80
MainBoard: 471-01A3-64201G ver: A3
IC MainBoard: CPU: MST6M48RHS-LF
Tuner: CDT-3FP2I2-31
RL-37B05F Specifications
ROLSEN RL-37B05F
General recommendations for TV LCD LED repair
Possible malfunctions
- TV ROLSEN RL-37B05F does not turn on. There are no signs of operability. The indicators on the front panel do not light or blink, and does not respond to the remote control and control buttons.
Usually with similar manifestations, the defect is caused by faulty elements in the main power module K-190N1. It is necessary to measure the secondary output voltages, and in their absence, check the serviceability of the power switches (TF20N60, K2645, F3NK80) of the converters and rectifier diodes for the probability of a short circuit.
In case of thermal and avalanche breakdowns of semiconductors in secondary circuits, the converter can usually operate normally in an emergency short circuit mode. There are no output voltages. And with a short circuit in the power elements of the primary circuit, as a rule, the mains fuse breaks and, less often, the current sensor in the source of the key.
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 supply, damper circuits, or elements of OOS (negative feedback) stabilization. The reason for the breakdown of the power switch can also be PWM (PWM) 1653A (PFC), MCP1396AG (16pin), A7350M (8pin). It is checked only by replacing it with a known good one.
- There is no image, there is sound, it reacts to the remote control. Or the image may appear for a second when turned on and disappear immediately.
In such cases, a malfunction of the LED panel backlighting elements is most likely. The reason for this may be an open circuit in the LED circuit, or a problem in stabilizing their power supply.
Without a special current source, it is impossible to check the line of series-connected LEDs, and it is unsafe for them to use any voltage sources above 12V for this purpose. Then all that remains is to open the panel and check each LED separately. Usually, Chinese multimeters with 9V power supply lightly light one 3-volt LED, if you connect the probes to it in the forward direction, the red probe to the anode, the black one to the cathode. For dual 6-volt LEDs, the PN junction of its emergency zener diode can serve as an indicator of the LED health. In the event of a malfunction of the LED, its zener diode will either be cut off, or broken through in the SC.
- 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 471-01A3-64201G motherboard should begin with checking the stabilizers and power converters required to power the microcircuits and matrix. If necessary, you should update or replace the software (software). Repair of the board and replacement of CPU: MST6M48RHS-LF microcircuits are made if the necessary equipment and the corresponding element base are available. Failures associated with the use of BGA soldering technologies can be localized by warming up.
If there is no reception of TV channels, but the TV is working properly from external devices, first of all, you need to check the supply voltage of the CDT-3FP2I2-31 tuner and update the software. I2C communication pulses must be monitored with an oscilloscope.
Owners of the RL-37B05F TV are advised to contact only qualified specialists with the necessary experience for repair! Attempts to repair yourself without the appropriate knowledge and skills can lead to irreversible negative consequences!

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 The appearance of the MainBoard 471-01A3-64201G is shown in the figure below:
471-01A3-64201G
External view of the power supply
The main features of the ROLSEN RL-37B05F device:
Installed matrix (LED panel) LC370WUN (SC) (A1).
Matrix control uses the Timing Controller (T-CON) 6870C-0310A.
The LED driver 6632L-0618A is used to power the backlight LEDs, it is controlled by the PWM controller BD9215AFV, AS324M-E1, KIA78M05F.
The formation of the necessary supply voltages for all nodes of the ROLSEN RL-37B05F TV is carried out by the K-190N1 power module, or its analogs using 1653A (PFC), MCP1396AG (16pin), A7350M (8pin) microcircuits and TF20N60, K2645, F3NK80 power switches.
MainBoard - the main board (motherboard) is a 471-01A3-64201G module, using CPU chips: MST6M48RHS-LF and others.
The CDT-3FP2I2-31 tuner provides reception of television programs and tuning to channels.
Additional technical information about the panel:
Brand: LG Display
Model: LC370WUN-SCA1
Type: a-Si TFT-LCD, Panel
Diagonal size: 37 inch
Resolution: 1920x1080, FHD
Display Mode: S-IPS, Normally Black, Transmissive
Active Area: 819.36x460.89 mm
Surface: Antiglare (Haze 10%), Hard coating (3H)
Brightness: 500 cd / m²
Contrast Ratio: 1500: 1
Display Colors: 16.7M / 1.06B (8-bit / 8-bit + Dithering)
Response Time: 5 (G to G)
Frequency: 60Hz
Lamp Type: EEFL Embedded (Inverter)
Signal Interface: LVDS (2 ch, 8/10-bit), 51 pins
Voltage: 12.0V
ROLSEN RL-37B05F LCD TV LCD LC370WUN, 37 "(94 cm) diagonal, 16: 9 format. Screen brightness of 500 cd / m² is backlit by CCFL (EEFL) fluorescent lamps. Dynamic contrast ratio of 50,000: 1 is ensured by special operation control illumination depending on the illumination of areas in the scene The design and technical capabilities of the TV provide viewing of broadcasts and films in high quality HD at a resolution of 1920x1080 pixels in graphic resolution according to the standard 1080p (Full HD) .Input high-frequency or video signal can be processed in analog systems PAL, SECAM, NTSC Graphic processing and digital signal shaping takes place in the standards 480i, 480p, 576i, 576p, 720p, 1080i, 1080p Supported media file formats: MP3, WMA, MPEG4, MKV, JPEG.
Speaker sound system power 20 W (2x10 W) is provided by two speakers. The NICAM STEREO audio processing system is used.
External interface (communication with other devices) is supported by standard input and output connectors: antenna input (RF), AV x2, S-Video x2, component, VGA, HDMI x2, USB. A headphone output is provided. To connect a computer or laptop to this TV model, a VGA (D-Sub 15) connector on the TV case is used, this interface supports resolutions: 640x480, 800x600, 1024x768.
The power consumed by the TV in operating mode from the network is 180 watts.
Dimensions: without stand 911x565x112 mm.
TV weight: 17.5 kg.
Attention! ROLSEN RL-37B05F LCD TV panel LC370WUN (SC) (A1) is its most expensive component.
Avoid hitting the glass and putting pressure on the screen surface to avoid irreversible damage to the LCD panel!