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• The system-EEPROM dump for LG TV model 42LB677V-ZC (chassis LD42B, main-board EAX65384005 rev 1.2 or EAX65384004 rev 1.5) is available on specialised repair portals such as
– remont-aud.net → LCD/PDP TV → LG → “42LB677V-ZC 24C256 dump” (IC103, AT24C256)
– forum-monitor.net.ru (section “EEPROM/FLASH dumps”)
– several invite-only telegram channels that mirror the same repository.
• Registration/login is normally required; direct redistribution is restricted by LG copyright, therefore the file itself is not attached here.
• Check that your board number and the LCD panel code match the dump description before programming.
Key points
Memory map of the main board
• AT24C256 (32 k × 8) – “System EEPROM”: model-specific data, EDID for HDMI, white-balance calib., region codes.
• SPI NOR flash (e.g. W25Q64) – 1st-stage bootloader.
• eMMC (BGA, 4–8 GB) – WebOS, user data, HDCP/CI+ keys.
Lost picture-calibration or Service Menu parameters → 24C256; endless boot loop or LG-logo freeze → eMMC.
| Board / panel cross-matrix | TV model | Main board | Typical panel | System EEPROM | Comment |
|---|---|---|---|---|---|
| 42LB677V-ZC | EAX65384005(1.2) | LC420DUH-FGP1 | AT24C256 | EU-market | |
| 42LB677V-ZC | EAX65384004(1.5) | LC420DUH-PGF1 | AT24C256 | Later rev. |
Why dumps are not interchangeable
• The first 256 bytes hold LVDS/T-CON drive voltages encoded for a concrete panel.
• MAC address (bytes 0x1F00–0x1F05) must be unique per device.
• CI+ keys (if present) are cryptographically bound to main SoC – overwriting them breaks paid-TV modules.
Typical failure scenarios solved by re-writing 24C256
• After factory reset the picture becomes inverted / solarised – corrupted panel block.
• Service Menu is inaccessible (―incompatible with this model‖ error).
• TV powers on with sound but without backlight – wrong LVDS parameters.
• Community repositories (Remont-aud, Monitortv, Badcaps) are continuously updated; the 2023-2024 dumps include board rev. 1.6 files that were not present earlier.
• More technicians copy only the first 4 kB (panel / white-balance) from the donor dump and merge it with the original to preserve unique keys – a trend enabled by modern hex-diff tools.
• Some service centres switch from I²C in-circuit programming clips to RT809H/VP998 programmers that can read the 24C256 without desoldering at 1 MHz with bus-isolation probes.
Potential future developments
• LG is gradually moving panel and calibration data into a secure partition inside the eMMC; models after 2016 (e.g. LJ, LK series) no longer have an external 24Cxxx.
Programming flow example (CH341A USB programmer):
Analogy: think of the 24C256 like a BIOS setup CMOS on a PC: it does not contain the OS, only low-level hardware parameters. Putting another PC’s CMOS image may boot, but date/time and PCI tables would be wrong.
• Dumps are LG intellectual property. Distribution without licence is legally grey in many jurisdictions; most forums rely on “service/backup” fair use.
• Any re-programming voids consumer warranty.
• Ensure ESD and electrical safety while working on open mains-powered TV chassis.
Potential challenges & mitigation
• “No acknowledge” during I²C access – pull SDA/SCL to VCC through 4.7 kΩ.
• After reflash TV stays in standby – power-cycle AND remove AC for 30 s; some LG main boards latch parameters only on cold start.
• If the TV is stuck on LG logo, EEPROM alone is rarely the cause – inspect eMMC health (Samsung KLMxGxx EMCP on IC8100).
• Panel code mismatch may produce vertical stripes indistinguishable from T-CON failure; always rule out EEPROM first.
• Board rev. 1.2 vs 1.5 dumps are 100 % compatible in the first 8 kB but differ in CI+ block; merging is advised.
• Study the LD42B service manual (available on elektrotanya.com) – contains I²C address map of IC103.
• Explore Easy-JTAG Plus scripts for live eMMC repair if 24C256 reflash fails.
• Keep an eye on forums for “SEC eMMC dead” cases – a rising issue on 2014-2015 LG WebOS sets.
Recommended resources
• remont-aud.net → section “Инструкция: работа с CH341A”
• Badcaps.net → “LG LB-series no backlight after reset” thread
• Service remote APP (Android) to access In-Start without original MR-600 remote – useful after EEPROM reflash.
The LG 42LB677V-ZC stores panel and service data in an external AT24C256 EEPROM (IC103). A verified dump matching your main-board (EAX65384005/004) and LCD panel is available on remont-aud.net and similar professional forums; download rights usually require registration.
Backup your original EEPROM, programme the donor/merged file with a 3.3 V I²C programmer, and cold-boot the TV. Double-check legal and safety aspects—using an incorrect dump can damage the set, and firmware files remain LG’s intellectual property.
