How I Repaired Dead and Flickering LED TVs Due to Low ESR Capacitors

 Dear friends,

As a service engineer with over 20 years of experience, I’ve seen many tricky faults in LED TVs. One of the most overlooked issues is capacitors with high ESR (Equivalent Series Resistance). Even if they look fine, they can silently kill the power supply or cause display issues.

Here are two real case studies from my recent repairs where low ESR capacitor failure was the root cause.

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🛠️ Case Study 1: Samsung 32" LED TV – Completely Dead

• Model: Samsung UA32FH4003

• Issue: No standby light, no power, totally dead

• Initial Check: Fuse OK, input voltage present

• Clue: No output voltage on power board (5V/12V missing)

🔍 Diagnosis:

I suspected the secondary side filter capacitors. With an ESR meter, I tested a 470µF/25V capacitor. Although it looked perfect physically, it had an ESR value of 5Ω, which is very high (normal < 0.2Ω).

🔧 Repair:

Replaced the faulty cap with a 105°C low ESR capacitor.

✅ Result: 5V and 12V restored, TV powered ON, backlight came up, display normal.

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🛠️ Case Study 2: LG 43" LED TV – Flickering Backlight & Auto Shutdown

• Model: LG 43LF540A

• Issue: TV starts with LG logo, backlight flickers, then shuts off

• Backlight & Mainboard: Working

• Suspect Area: LED driver power section

🔍 Diagnosis:

Checked filter capacitor in the LED power line – found 220µF/35V capacitor showing ESR of 3Ω. This causes unstable voltage, leading to flickering and shutdown.

🔧 Repair:

Replaced with a Panasonic low ESR capacitor.

✅ Result: Backlight stable, no shutdown, display OK.

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🧠 What We Learn from These Repairs:

• High ESR = Low Efficiency. Even if a capacitor shows correct µF value, high ESR can cause ripple, shutdowns, or no output.

• Always check ESR when TV is dead or shows display issues.

• Use branded, low-ESR capacitors rated for 105°C, especially in SMPS and LED driver sections.

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💡 Tip for Technicians:

If the board fuse is fine and there’s no output, don’t just check for bulging caps. Use an ESR meter and check every output filter capacitor. One faulty cap can shut down the whole board.

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If you're a technician or electronics enthusiast, never underestimate ESR – it can be the silent killer behind many LED TV issues.

Regards

Basavaraj BM