Czy wolisz polską wersję strony elektroda?
Nie, dziękuję Przekieruj mnie tamemmc kd-49x755f
• Sony’s KD-49X755F keeps its Android-TV operating system, boot-loader and user data in an embedded MultiMediaCard (eMMC) that is soldered (BGA package) on the main board.
• When this eMMC becomes corrupted or reaches its write-endurance limit the set will typically a) stay on the SONY / ANDROID logo, b) loop-boot, or c) show no standby LED at all.
• If software recovery (forced factory-reset or USB firmware re-install) does not cure the fault, the only permanent fix is either
– professional re-programming / replacement of the eMMC, or
– swap of the complete main board (most consumer-friendly solution).
Key points
– Unknown from public literature, but field-opened boards show 8 GB or 16 GB Samsung, Hynix or Toshiba eMMC (e.g. Samsung KLMAG2GEND-B031 on sister models).
– Chip is BGA 153, supplied with 1 V8 / 3 V3 rails and HS200 signalling.
– A blank device must be fully flashed (boot0/boot1, RPMB, GP partitions, Android images, HDCP/DRM keys); otherwise the TV will not boot or will lose Netflix / Widevine.
– Programming requires a service jig (Easy-JTAG, UFI, Medusa, etc.) or in-circuit ISP pads.
Function and architecture
• KD-49X755F uses a MediaTek “MT58xx” SoC + separate eMMC on the main board.
• The eMMC holds:
– Boot ROM extension (boot0 / boot1)
– Android partitions (system, vendor, userdata, cache)
– DRM keys (Widevine L1, PlayReady, HDCP 2.2) – model-unique!
– Region / option bytes (panel ID, IR table, language pack, etc.)
Failure mechanisms
• Wear-out: small-capacity (8 GB) devices in smart-TVs are easily driven beyond their P/E cycle rating by log files, app updates and cached video.
• Voltage glitches during an update corrupt the flash translation layer (FTL).
• Excessive heat or liquid ingress can lift BGA balls.
Symptom matrix
| Symptom | Probable root cause | First-line action | If unresolved |
|---|---|---|---|
| Stuck on SONY/Android logo | Corrupted ‘system’ or ‘userdata’ partition | Forced factory-reset (VOL- / POWER keys while powering-on) | USB firmware re-install → eMMC re-write → board swap |
| Endless reboot | Bad blocks in boot area | Recovery menu → “wipe cache” | eMMC re-flash or replace |
| No standby LED | 12 V, 5 V supplies OK, but MCU not running | Suspect eMMC not answering SoC | BGA re-work or full board |
| Apps crash / slow menus | Wear-induced read-retry | Settings > Device > Storage – check free space | Back-up, factory-reset, consider preventive replacement |
Software-level recovery
a) Ordinary factory reset: Settings → Device Preferences → Reset.
b) Forced factory reset (TV keys): Hold Vol- & Power on the TV (not remote) while inserting mains until “green LED blink” sequence.
c) USB firmware (.pkg) re-install:
– Download KD-49X755F_6.9624 or newer from Sony support site.
– FAT32 USB, file in root directory.
– Insert → hold POWER on remote → plug mains.
If the loader cannot mount the eMMC the update will never start—confirming a hardware fault.
Hardware-level service workflow
| Step | Action | Notes |
|---|---|---|
| 1 | Remove back cover, locate MAIN board (part 1-982-022-31 or 1-982-022-41 depending on region). | Observe ESD precautions. |
| 2 | Confirm board rails (5 V, 3 V3, 1 V8) present on power-up. | If rails missing, PSU/A-board fault precedes eMMC. |
| 3 | Identify eMMC (U5037 on silkscreen). Record full part code. | Typical: Samsung KLMAG2GEND-B031 (16 GB), Toshiba THGBMHG6C1LBAIL (8 GB), etc. |
| 4 | Attempt in-system read with ISP pads and Easy-JTAG; if readable, clone for safety. | Needed to preserve DRM keys. |
| 5 | If unreadable / BAD, hot-air remove BGA, clean pads, mount new pre-reballed chip. | 260 °C top / 150 °C preheater typical. |
| 6 | Program full dump or official service image + keys. | Sony service files are not publicly distributed; technicians copy from donor board. |
| 7 | Power-test on bench, verify boot, run self-diagnostic (Display > 5 > Volume+ > Power). | Check 005:0 errors (DRM). |
| 8 | Update to latest firmware, pair Bluetooth remote, recalibrate panel if Option bytes lost. |
Critical obstacles
• Firmware availability – Sony public update package lacks boot and DRM partitions.
• HDCP / Widevine – if keys are lost Netflix 4K, Prime HDR will be blocked.
• Tools – inexpensive ‘USB-ISP’ dongles cannot handle 1.8 V HS200; professional box required.
• Skill – 0.5 mm pitch BGA on 1.0 mm PCB; risk of pad lift is high.
Cost / benefit
– Blank 16 GB eMMC: ≈ 8 USD
– Programming box: 150-300 USD
– Lab labour: 60-120 USD
– Complete main board (refurb): 120-160 USD (availability fluctuates; see sony.encompass.com, partstown, AliExpress).
For non-technicians the board swap is the only economical path.
• Field data (2023-2024) from EletronicaBR and Russian + EU repair fora show rising eMMC mortality on 2018-2020 Sony Android TVs; 49-inch X7-series among the most affected.
• Repair shops increasingly keep pre-programmed, generic “BMKS” Sony images; companies such as MJK-Electronics sell programmed chips / swap service with Netflix keys restored.
• Some independents migrate to larger 32 GB eMMC to improve endurance; not officially endorsed by Sony but works when CID is left unchanged.
• Next-generation sets (Google TV 2022+) move to UFS, doubling throughput and endurance—making future failures less frequent.
• Why eMMC fails sooner than expected: Unlike smartphones, TVs stay in standby and run background logging 24 h/day; small-capacity devices perform more garbage-collection cycles → more P/E wear.
• Analogy: eMMC is to the TV as BIOS flash + SSD combined; if it dies the “brain” has no OS to boot.
• Example case: A Brazilian technician (EletronicaBR thread #335401) salvaged a KD-49X755F with no standby LED by flashing a KD-49X7005 dump; set powered but lost CAST / DRM until proper regional keys were injected.
• DRM keys are copyrighted; distributing full dumps publicly violates Sony licence terms.
• Any content-protection breach (e.g., cloning HDCP keys) may infringe DMCA-style laws.
• Safety: BGA rework stations involve 260-300 °C; fire hazard and toxic fumes—use fume extraction and PPE.
Potential challenges & mitigation
– No firmware dump → seek donor board of same chassis, read, then program.
– Pads lifted → route thin wires to adjacent via or scrap board for donor pads.
– Customer expectations → warn that some streaming apps may refuse wide-vine L1 until Sony servers re-authorise (may take 24 h online).
• Information based on service manuals, field repairs and 2024 community reports; Sony does not publicly confirm individual component part numbers.
• Not all KD-49X755F main boards are interchangeable (suffix 31 vs 41 have different Bluetooth modules).
• Replacing the eMMC yourself voids any remaining manufacturer warranty.
• Measure real-world write-amplification on Android-TV 9 vs 10 to predict eMMC life.
• Study possibility of migrating to a pin-compatible 32 GB or 64 GB eMMC with firmware-level wear-levelling improvements.
• Develop open-source script to extract and reinject Sony DRM key blobs automatically after dump transfer.
• Monitor transition from eMMC to UFS in consumer TV SoCs and its long-term reliability impact.
The KD-49X755F’s eMMC is the single point of failure for booting and smart functions. Manifestations range from simple sluggishness to a black, LED-less set. Start with forced factory reset and USB firmware reload; if the TV cannot access the storage, professional intervention is required. Chip-level repair—BGA removal, programming with a full firmware dump including DRM keys, and re-soldering—demands specialised tools and know-how. Most end-users will find a complete main-board replacement faster and safer. Protect the new eMMC by keeping free space, avoiding power cuts during updates and ensuring adequate ventilation.
