Fault in Backlight Circuit Sony KLV-46R452A
Sony KLV-46R452A Display Not Working This Sony Bravia model occasionally drops the display due to a fault in the backlight circuit. When this set was brought to the workshop, it was working perfectly. I tested it for two days and during that time it continued to operate normally without any issues. In this article, we will walk you through step by step how this display fault was diagnosed and how it was finally fixed.
Fault Overview & Symptoms
Before diagnosing this fault, it is important to understand what the actual nature of the fault is. In this particular case of the How to Fix Display Drop Issue in Sony KLV-46R452A, the problem was obvious: the TV’s backlight would turn off almost immediately after powering on, while the sound would often be audible. This makes it clear that the problem is not a complete power failure, but rather in the backlight circuit.
A key observation confirmed this diagnosis. If the backlight assembly itself were completely faulty, the TV’s protection circuit would typically trigger a 6-blink error code on the power LED. Here, no such error occurred; only the display dropped out. This critical difference isolated the problem to the backlight driver or inverter circuit, where an intermittent fault—often related to a failing capacitor, a weak solder joint, or a overheating component—was causing the sudden shutdown.
Diagnosing the BD9397EFV Backlight Circuit
I opened the back cover of this set and started analyzing its backlight circuit, then I heard a very faint sound from it. At that time the circuit was working and the display was on. BD9397EFVIC IC is used in this circuit. This sound coming from the circuit made me realize that a resistor connected to this IC could possibly be faulty.Now the next step was to check its resistors.Â
The Faulty Resistor on Pin 35 (VREF)
Pin 35 of the BD9397EFV IC is its reference pin, but in this area there are voltage divider resistors consisting of three resistors. I removed all the resistors from the circuit board and checked their values. One of the resistors had increased significantly in value. This resistor was part of the voltage divider network connected to ground.
The Fix: Replacing the Faulty 22K Resistor with 2.2K
Its value on the multimeter was showing 22K and was constantly going up and down while checking. After some research, I replaced this resistor with a value of 2.2K. After the replacement, the sound in the circuit disappeared. In the image below, you can see the bad resistor—I have marked and replaced this bad resistor. With this change, the display fault was successfully corrected.
- Display Drop Issue in Sony KLV-46R452A.
- occasionally drops the display.
- There was noise in the backlight circuit.Â
- due to a fault in the backlight circuit.
- BD9397EFV A resistor was found on pin number 35.
- Diagnose the up and down in the overall value of this resistor.Â
Main board full imageÂ
Below you can see the full image of the mainboard of this model.The backlight area is also circled in it.
Key Takeaways & Final Thoughts
According to my expert opinion, the reason for this fault is that these Bravia models are quite old, so their components are also at the end of their life. Such chip-level problems can only be solved by an expert technician. In this case, the problem was in the reference of the IC in the circuit. This IC is commonly used in Sony Bravia models, so we will write a separate article on this IC, in which we will explain how this IC works.
Conclusion
How to Fix Display Drop Issue in Sony KLV-46R452A You saw how we diagnosed this Sony fault. The problem was that the display would automatically disappear. A problem was discovered in its backlight circuit. A resistor near the main IC in the backlight circuit was found to be faulty, after replacing it, the fault was fixed. Sony LED TV Repair Center Lahore will continue to publish such faults for you which are fixed with great effort.
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Shaukat Ali has over 30 years of experience in LED TV repair, specializing in chip-level repair work. He is an expert in Sony LED TVs, and also repairs other major brands like Samsung, TCL, Orient, and Haier. His expertise includes display panel faults, motherboard issues, power supply circuits, T-Con, and HDMI faults. Based in Lahore, he shares real-time fault finding cases from daily repair work to help technicians and learners with practical experience.
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