Czy wolisz polską wersję strony elektroda?
Nie, dziękuję Przekieruj mnie tamHI. I am having the same issue. Almost endless beeps every 3 secs, with black screen. For now I detected 4 voltage regulators. I have got the following measures: IC111 5Vdc 12kOhm, IC114 5Vdc 12kOhm, IC108 3,7Vdc 59kOhm, IC113 0,75Vdc 10kOhm.
I am now looking for the electrical diagram, to see if these voltages are ok. Have you measured your Voltage regulators?
Key points
• 3.7 V on a logic rail that should be 3.3 V is already above the absolute-maximum rating of most devices – power-down and repair first.
• Identify the regulator part numbers, consult their data sheets, and confirm their intended outputs.
• Replace (or temporarily disconnect and bench-feed) the suspect regulators, then re-measure every rail under load before further diagnosis.
Boot / beep loop mechanism
• Samsung main boards start from the 5 V standby rail.
• An embedded controller or the main SoC monitors the appearance, sequence and tolerance of subsequent rails (5 V, 3.3 V, 1 .x V, 0 .x V, panel Vdd, etc.).
• If any rail is out of spec for more than a few milliseconds the watchdog resets the board and you hear the periodic beep.
Interpretation of your four measurements
• IC111, IC114 – 5.0 V at ≈12 kΩ when un-powered → normal standby / logic rail.
• IC108 – 3.7 V at ≈59 kΩ. Nearly every BN41-00xxx board uses a fixed 3.3 V LDO or buck regulator here (often an AMS1117-3.3 or RT9166-33).
– 3.7 V indicates the regulator has lost feedback, is running open-loop, or has excessive input.
– Anything >3.6 V can permanently damage the SoC, SDRAM, SPI-NOR/NAND and HDMI receivers tied to this rail.
• IC113 – 0.75 V at ≈10 kΩ. The core rail (VCORE) for the ARM/MIPS SoC on Samsung TV boards is commonly 1.0–1.2 V. 0.75 V is therefore suspect unless the data sheet for that specific SoC calls for such a low voltage in reset. Typical failure modes:
– The upstream 3.x V rail is wrong (already evident at IC108), so the step-down regulator never reaches regulation.
– The regulator itself is current-limited owing to an internal fault or a heavy downstream short (less likely given the 10 kΩ static reading).
Chain of causality
Over-voltage on 3.3 V (IC108) → SoC detects illegal voltage → internal brown-out / thermal lockout or physical damage → VCORE regulator held low or shut down → watchdog reset → audible beep.
If the over-voltage has persisted for long, the SoC or its DDR may already be compromised; however, experience shows many sets will still boot once the 3.3 V rail is repaired, provided the over-voltage never exceeded ≈3.9 V for an extended time.
Why resistance readings alone are not decisive
• Multimeter “Ω” mode injects just a few hundred millivolts; CMOS structures behave like back-to-back diodes, so you read essentially the resistance of leakage paths, not the true load under 3 – 5 V.
• Use resistance only to detect gross shorts (<10 Ω). Your 59 kΩ and 10 kΩ readings simply tell us there is no hard short.
What a correct rail set should look like on a BN41-00825 (common values taken from working boards and Samsung service documentation)
• +5 V_STBY / +5 V_MAIN … 4.90 – 5.20 V
• +3.3 V_L … 3.25 – 3.35 V
• +1.8 V_IO … 1.7 – 1.9 V
• +1.2 V_VDDQ (DDR) … 1.14 – 1.26 V
• +1.0/1.1 V_VCORE … see SoC spec, usually 0.95 – 1.15 V
• Panel supplies (+12 V, +24 V) come up only after the main board finishes POST and asserts BL-ON.
• Samsung has not released full schematics for post-2010 TV main boards; the repair community relies on crowd-sourced reverse-engineered diagrams and annotated board photos.
• “Chip-level” repair is resurging thanks to inexpensive hot-air stations, budget microscopes and component testers; replacing SOT-223/SOT-89 LDOs or 8-pin buck converters is routine.
• More recent TV SoCs (2017-2024) integrate the PMIC, making discrete regulator replacement impossible; your BN41-00825 is still discrete and therefore serviceable.
Voltage regulator basics
\[ V{OUT} = V{REF}\left(1+\frac{R_1}{R_2}\right) \] for adjustable types.
A lost ground pin, cracked feedback resistor or dried-out output capacitor can shift VOUT upward (seen in IC108).
Example: AMS1117-3.3 absolute maximum rating = 4.2 V. Operating at 3.7 V stresses the part but mainly endangers the load.
Analogy
Think of the board as a multi-stage water-pressure system. If the first stage (3.3 V pump) overshoots, downstream regulators either shut their valves (0.75 V rail low) or rupture.
• Schematics remain proprietary; redistribution without Samsung’s consent may infringe copyright.
• Ensure mains isolation and discharge primary capacitors before probing; lethal potentials exist even with the set unplugged.
• Data privacy: if the NAND flash is replaced, user settings and stored channel data are erased – inform the owner.
Identify parts
‑ Read the top marking of IC108 & IC113 (e.g., “1117-33”, “MP2307DN”, “SY8008”).
‑ Download the data sheet, confirm expected VOUT.
Replace / simulate
‑ Desolder the suspect regulator; feed 3.30 V from a current-limited bench supply into the rail pad.
‑ If the board boots, replace the LDO/buck converter permanently.
Post-repair verification
‑ Scope each rail for ripple (<50 mV p-p).
‑ Check that power-good (PG, POK) pins toggle high in the documented order (5 V → 3 .3 V → 1 .x V).
Firmware contingency
If voltages are corrected and the set still beeps, re-flash the SPI-NOR/NAND with known-good firmware (available on BadCaps, Elektroda archives).
Potential challenges & mitigation
• BGA SoC damage → board not salvageable; replacement board cheaper.
• No schematic → create your own rail map with continuity mode and photo annotation.
• Continuous 3.7 V exposure may already have degraded flash memory; success is not guaranteed.
• Some boards label rails on inductors (e.g., “L3003 3V3_S”). Use these clues when a schematic is absent.
• Reverse-engineer the power section with KiCad or EasyEDA to create an open community schematic.
• Investigate automatic rail-monitor ICs (e.g., TPS3860) used in later Samsung boards for predictive failure analysis.
• Explore thermal imaging or VI-trace (curve-tracer) methods for faster component-level diagnostics.
Resources
• BadCaps.net thread “Samsung 225MW EEPROM boot-loop” – contains partial rail map for BN41-00825.
• Electronica-PT BN41 index – searchable PDFs of older Samsung schematics; some rail values are identical.
• Application note: ON-Semi AND8302 “Troubleshooting linear regulators”.
Your BN41-00825 is trapped in a protection loop because at least one critical rail is wrong. The 3.7 V reading on IC108 is the prime suspect (expected ≈3.3 V). Replace or externally feed that rail, then re-check all other regulators, especially the 0.75 V core rail. If rails stabilise and the set boots, the fault was limited to the regulator; if not, the SoC or firmware may already be damaged, and full board replacement might be more economical. Systematic measurement, part-number verification and cautious power-up will yield the quickest, safest resolution.
