Saturday 28 December 2019

REPAIRING / SERVICING TV SAMSUNG LT27C370EX

Technical description and composition of the SAMSUNG LT27C370EX TV, panel type and applicable modules. The composition of the modules.
SAMSUNG LED
Model: LT27C370EX
Panel: LTM270HL01
LED driver (backlight): integrated into MainBoard
PWM LED driver: SLC5013R
MOSFET LED driver: GA3S29, G4435SS
Power Supply (PSU): Adapter A5814-DSM DC 14V 4.143A 58W
PWM Power: PWM
MainBoard: BN41-01987A BN94-06267H
IC MainBoard: SENK13, 25Q40CLSIP, K4B1G1646G-BCKO, 1326-CB
Tuner: BN40-00261B GT2CX-3B / K3S
Technical Specifications LT27C370EX
SAMSUNG LT27C370EX
General repair guidelines for TV LCD LED
Possible malfunctions
- The SAMSUNG LT27C370EX TV does not turn on and does not show any signs of operability at all. There is no reaction to the remote control and control buttons.
In most such cases, a fault is detected in the power module.
The external adapter A5814-DSM DC 14V 4.143A 58W power supply is not always subject to repair, especially since the owner can purchase it independently. But, in some cases, it makes sense to open it and eliminate the simple typical defects inherent in converters in pulsed sources. It is necessary to measure its output voltages and, if they are absent, check the power switches and rectifier diodes for the probability of a short circuit.
In the event of breakdowns in the secondary circuits, the converter may emergencyly operate in the short circuit mode, and during a short circuit in the power elements of the primary circuit, the mains fuse usually breaks.
Mos-Fet keys used in switching power supplies usually fail due to a malfunction of other elements that can put it out of operation in key mode or provoke an excess of the maximum current or voltage. These can be elements supplying the PWM controller, frequency-setting and damping circuits, or elements of OOS (negative feedback) stabilization. The reason for the breakdown of the power key can be PWM (PWM) PWM. It is checked by replacing with a known good one.
- There is no image, there is sound, it responds to the remote control, the channels are switched. In some cases, the image appears when you turn on and immediately disappears.
Usually in such cases, a malfunction is detected in the backlight nodes of the LED panel. The reason for this may be a break in the LED circuit, or a problem in stabilizing their power supply.
To check the LED lines for breaks without disassembling the panel, for example, a current source will help. It is impossible to open series-connected PN-junctions with a simple multimeter, a voltage of the order of several tens of volts is required.
- The indicator blinks or glows constantly, the TV does not turn on, does not respond to the remote control.
Repair or diagnostics of the BN41-01987A motherboard should begin by checking the stabilizers and power converters needed to power the chips and matrix. If necessary, you should update or replace the software (software). Sophisticated MB board repair (SSB) is in some cases possible and practiced by repairmen. To do this, check and, if necessary, replace the elements SENK13, 25Q40CLSIP, K4B1G1646G-BCKO, 1326-CB. BGA chip malfunctions are usually easy to detect by warming up.
In the absence of tuning to the channels of terrestrial or cable television, you should make sure that the software is correct, as well as in accordance with the ratings of the supply voltage at the terminals of the tuner BN40-00261B GT2CX-3B / K3S. It is also necessary to check the presence of pulses of data exchange between the tuner and the processor via the I2C bus using an oscilloscope.
Attention to users! Self-repair of a SAMSUNG LT27C370EX TV without the appropriate qualifications and the necessary experience can lead to its complete non-repairability!


The appearance of the MainBoard BN41-01987A is shown in the figure below:
BN41-01987A
BN41-01987A can be used in TVs:
SAMSUNG UE28F4020AW (Panel HF280AGH-R1), SAMSUNG LT27C370EX (Panel LTM270HL01), SAMSUNG UE22F5000 UE22F5000AK (Panel M215HW03 V.1), SAMSUNG UE28F4000 UE28F4000AW-C1 H2.
Main features of the SAMSUNG LT27C370EX device:
Installed matrix (LED-panel) LTM270HL01.
To power the backlight LEDs, a converter is used, combined with the main board BN41-01987A, controlled by the SLC5013R PWM controller. As power elements of the LED driver, keys of the type GA3S29, G4435SS are used.
To power all internal components of the SAMSUNG LT27C370EX TV, an external adapter type A5814-DSM DC 14V 4.143A 58W is used using PWM chips.
MainBoard - the main board (motherboard) is a BN41-01987A module, using SENK13, 25Q40CLSIP, K4B1G1646G-BCKO, 1326-CB and other chips.
The tuner BN40-00261B GT2CX-3B / K3S provides the reception of television programs and tuning to channels.
Information from an alternative source:
SAMSUNG LT27C370EX / CI
Panel Type (Matrix): LTM270HL01,
Motherboard: BN94-06267H BN41-01987A, SENK13, 25Q40CLSIP, K4B1G1646G-BCKO, 1326-CB, Tuner: GT2CX-3B / K3S BN40-00261B, LED backlight :, Driver SLC5013R, Mosfet GA3S29, Power key GSS: P35SS3535, Power backlight GSS: A5814-DSM DC 14V; 4.143A; 58W
Remote control: AA59-00823A
Additional technical information about the panel:
Brand: SAMSUNG
Model: LTM270HL01
Type: a-Si TFT-LCD, Panel
Diagonal size: 27.0 inch
Resolution: 1920x1080, FHD
Display Mode: PLS, Normally Black, Transmissive
Active Area: 597.888x336.312 mm
Surface: Antiglare (Haze 25%), Hard coating (3H)
Brightness: 300 cd / m²
Contrast Ratio: 1000: 1
Display Colors: 16.7M (6-bit + Hi-FRC), CIE1931 72%
Response Time: 15 (G to G)
Frequency: 60Hz
Lamp Type: 13S3P WLED Without Driver
Signal Interface: LVDS (2 ch, 8-bit), 30 pins
Voltage: 5.0V