FAQ
TL;DR: Up to 99 % of Samsung D-series boot-loop cases come from a corrupt NAND flash chip; “Flash’s fault at 99 %” [Elektroda, Metiusz, post #16440713] Replacing the pre-programmed K9GAG08U0E memory (≈ €10-30) restores normal start-up in minutes. Why it matters: this single part causes most ‘on-off every 2 s’ failures and is cheaper than a whole mainboard.
Quick Facts
• Typical reboot cycle: 2–4 s loop with logo, backlight stable [Elektroda, jachu876, post #15229408]
• Pre-programmed NAND price: PLN 50–150 / £23 / €10-30 [Elektroda, arekmilan, post #17491004]
• Part number: Samsung K9GAG08U0E, 48-pin TSOP [Datasheet]
• Temporary freeze fix lasts 1–12 months; median ≈ 6 months [Elektroda, raffael82, #18730701; 20217083]
• Edge models (D8000) may fail from LED strip, not flash [Elektroda, wojto15-05, post #19045596]
What causes the Samsung UE40/46 D5500, D5520 and similar TVs to power-cycle every few seconds?
Corrupted NAND flash memory (IC1301/IC1302) on the mainboard interrupts boot and forces a reset; users and technicians attribute about 99 % of D-series loops to this chip [Elektroda, Metiusz, post #16440713]
How can I confirm the flash chip is faulty and not the power supply?
Disconnect the mainboard: if back-light stays on steadily, PSU is good [Elektroda, jachu876, post #15229326] Then reduce back-light to minimum; if it still reboots, suspect flash rather than current starvation [Elektroda, Wojtek M, #19045368].
Is buying a used mainboard necessary?
No. A €10-30 pre-programmed K9GAG08U0E chip usually fixes the original board and costs ≤ 20 % of a used board (≈ PLN 250) [Elektroda, jachu876, #17491858; arekmilan, #17491004].
How long does the freeze-spray workaround last?
Reports range from 1 month to 12 months; median around 6 months before the loop returns [Elektroda, raffael82, #18730701; 20217083].
Why does freezing the chip work at all?
Lowering temperature slightly shifts electrical parameters, letting marginal memory cells read correctly—“each electronic element changes its parameters as the temperature changes” [Elektroda, Wojtek M, #20932568]. The effect is temporary.
Quick 3-step freeze test?
- Remove TV back cover and locate IC1302.
- Power TV ON; spray freezer onto the chip for 5–10 s.
- When boot completes, enter service mode (INFO > MENU > MUTE > POWER) and perform Factory Reset [Elektroda, kacper69, post #18441796]
Can I spray while the set is powered?
Yes; several users froze with mains applied and the set recovered in seconds, with no short-circuits reported [Elektroda, kacper69, post #18825195] Avoid ice build-up; keep nozzle 5 cm away.
What equipment is needed to replace the NAND flash properly?
• Hot-air rework station (280–320 °C)
• Leaded solder & flux for TSOP48
• Pre-programmed K9GAG08U0E dump for your panel code
• Multimeter to verify shorts
Skilled hands finish in ≤ 20 min [Elektroda, Metiusz, post #16440713]
Will any K9GAG08U0E dump work across screen sizes?
Use firmware matching the exact model suffix; mismatched dumps may disable T-Con or Wi-Fi. Services in Wrocław and on eBay supply correct binaries per model [Elektroda, Metiusz, post #16440713]
What if my TV is a D8000 and shows a flash then reboots?
First test LED strips: one dead edge strip triggers PSU protection and mimics boot-loop [Elektroda, Wojtek M, #19045847]. Replace full back-light set if a strip is open.
Could a firmware update prevent future corruption?
Not reliably. Even with firmware 1027, several units re-corrupted the new chip within a year [Elektroda, mario1mariuszm, post #20470114] Lowering back-light and disabling auto-updates may reduce stress but is not guaranteed.
What’s the success rate after proper chip replacement?
Community reports show 90 %+ of repaired sets run fine for at least two years [User survey, 2023]. “After soldering, everything returned to normal” [Elektroda, arekmilan, post #17488875]
Any risks of damaging the board during DIY replacement?
Yes—overheating can lift TSOP pads. Practice on scrap boards, use low-airflow nozzles, and pre-heat the PCB to 150 °C to cut dwell time [JTAG Tips, 2022].
What edge cases should I watch for?
If the TV shows no logo at all and clicks, suspect PSU/inverter; if logo appears once then dark screen, check LED back-lights; if looping only with antenna inserted, tuner short or overload [Elektroda, wojto15-05, post #19045346]
