[Solved] JVC 39 Vestel MB181TC TV Only Responds to Power Commands From Remote

asenikonomov301 wrote:

Hello, I am experiencing a problem with a 39'' 768p JVC television made by Vestel. It has the MB181TC board. Basically, the only commands accepted by the TV from the remote are turn off and turn on. H...

Initial assessment of available information
- Device: JVC 39" HD (768p) built on Vestel platform, mainboard 17MB181TC (often shortened to MB181TC).
- Symptom: IR remote only toggles power (standby ↔ on). No response to any other IR keys. TV plays HDMI audio and all local joystick/knob functions work. IR board swapped, two different “Vestel” remotes tried. Panel is physically broken; disconnecting LVDS did not change behavior.
- Unknowns: Prior history, hotel/child-lock status, firmware/profile version, and whether remotes used match the board’s configured IR code set.

Key takeaway: The IR receive path and standby wake are alive, but the running OS ignores non‑power IR keys. That almost always points to software/configuration (remote code profile or lockout) rather than a raw hardware fault on MB181.

Direct answer to the question
Yes—this “power-only” IR behavior is a known Vestel pattern. The most common causes on 17MB181/MB18x are:
- Remote code/profile mismatch (board expects a different IR protocol/keymap than your remotes send).
- Hotel/keyboard lock settings (IR restricted; power still allowed).
- Corrupted NVM/profile or partially corrupted firmware partitions that disable or mis-map IR handling.

True hardware failure on the IR line inside the SoC is possible but unlikely given power toggling works and you have the same result with two IR boards.

Detailed problem analysis
1. Why power works while everything else doesn’t
- On Vestel, the standby domain (or bootloader) watches for a subset of IR codes (notably POWER) to wake/sleep the set. Once the OS is up, a brand/panel-specific “profile” determines the IR protocol and key mapping. If the profile expects, say, a JVC-NEC variant and you send a different Vestel RC-type, POWER may still be recognized (fallback/boot handler), while other keys are discarded by the main IR driver.

2. Remote type/profile specifics
- Vestel ships identical hardware to many brands. The exact IR protocol (NEC-extended vs RC5/RC6 variant) and key table are selected by the “SW profile” and NVM parameters (often named Remocon/RC_Type). If these don’t match your handset, you get precisely your symptom.
- Two “Vestel” remotes doesn’t guarantee a match. A Telefunken/Grundig/Sharp-Vestel remote can differ from a JVC-Vestel profile.

3. Hotel/lock modes
- Hotel, public display, or keyboard/IR lock can disable most IR keys but still allow power. This is common in e‑waste units that came from hotels, schools, or demo walls.

4. Panel status
- Broken/detached panel doesn’t normally suppress IR, and your LVDS test supports that. Video path faults won’t explain “power-only” IR on MB181.

5. Why hardware failure is less likely
- You swapped the IR/LED board. The IR demodulator’s output clearly reaches the SoC at least for POWER. A gross 3.3 V/5 V rail or oscillator issue would not selectively ignore only non‑power IR keys while the joystick and HDMI audio run normally.

Current information and trends
- On MB181/MB18x generations, brand+panel “profiles” are commonly re-flashed in the field (USB auto-update). Many “strange control” symptoms (wrong keymap, no menu/vol, wrong brand splash) resolve after loading the correct profile for the board barcode and panel code.
- Service (“hotel”) parameters live in I2C NVM (24Cxx) or a config partition; clearing or restoring a proper profile often resets IR behavior.

Supporting explanations and details
- IR chain check: The IR module outputs active‑low demodulated pulses to the SoC GPIO. Seeing POWER wake proves the optical front-end, the 5 V_STBY supply to the IR board, the signal line, and the SoC’s basic IR interrupt are all alive. The decision to accept or ignore a given key happens in the OS driver using the profile’s keymap.

Practical guidelines (what to do next)
Follow in order—least invasive to most:

1. Eliminate handset mismatch in 5 minutes:
- Test with a universal remote set to multiple code sets: “JVC (Vestel-made TV)”, “Vestel”, “Toshiba (Vestel)”, “Technika/Bush (Vestel)”. Try MENU, VOL+, OK, 0…9 after the set is ON.
- If you have a learning/programmable remote, load a known Vestel NEC profile (e.g., common RC4812/RC4848 families) and also try a JVC-NEC profile. If suddenly the keys start working, you’ve confirmed a profile mismatch.
- Quick sanity: smartphone camera test ensures all keys on your remotes actually emit IR; if some do not, fix/replace the handset.

2. Check for hotel/IR lock using only the joystick:
- With the TV on, long-press the joystick center to bring up the main menu (works on most Vestel). Blind navigation (since panel is broken) is hard, but you can use HDMI-CEC as a workaround:
- Connect a CEC-capable HDMI source (Fire TV, Roku, PS4/5). Use the source remote to send CEC navigation to the TV. Sometimes you can reach Settings → System → First Time Installation/Factory Reset and clear locks without an IR handset.
- Typical hotel unlock/service entries include MENU → 4725 or MENU → 7935, etc., but those require a working IR MENU key. If you can’t send them, proceed to step 3.

3. Observe what the OS sees (UART log), no screen required:
- MB181 usually exposes a 3.3 V TTL UART on a small 3–4 pin header near the SoC or board edge (often silked “UART”, “JP…”, or “CN…”, not on the VGA DDC pins). Do not assume VGA or SCART pins are UART.
- Connect a USB‑TTL adapter (3.3 V). Typical 115200 8N1. Ground to board ground; PC RX to board TX.
- Power the TV and watch the boot log. Press several remote keys:
- If you see IR key codes being received but tagged “unknown/ignored”, it’s a protocol/keymap mismatch or hotel restriction.
- If only POWER produces log entries, the IR driver may be locked down (hotel) or the profile excludes your handset codes.

4. Non-destructive recovery: USB profile/firmware refresh without a display:
- Prepare a FAT32 USB stick with the exact MB181 package for the JVC variant (must match board barcode and panel code; wrong files can brick or misconfigure).
- Many MB181 boards support an “emergency/auto” update without IR:
- Unplug AC, insert USB.
- Press and hold the mainboard joystick (center press) while plugging AC; keep holding 10–15 s until the standby LED pattern changes (often fast blinking), then release.
- Wait 5–10 minutes for completion, then power cycle.
- Aim to refresh both the SW profile and (if available) the IR keytable component. This frequently restores correct IR behavior.

5. NVM (24Cxx) reset as a last resort:
- Identify the 24Cxx I2C EEPROM (8‑pin SOIC near the main SoC). Use a clip/programmer (e.g., CH341A with 3.3 V adapter) to read and save the contents first.
- Either write a known-good dump for your JVC/MB181 or blank the EEPROM (0xFF). On next boot the TV will reinitialize defaults and run first-time installation, typically restoring IR defaults. Risk: wrong defaults can misconfigure panel/backlight (panel already broken in your case) and require a proper profile flash anyway.

6. Hardware sanity checks (quick):
- Confirm IR board supply: +5 V_STBY ≈ 5.0 V on IR module VCC; check series resistor and decoupling cap.
- Scope the IR signal at the mainboard connector: you should see clean low-going pulses for every key you press, not just POWER. If you only see activity for POWER with both remotes, your remotes are not sending compatible codes.

Ethical and legal aspects
- Firmware/profile packages are brand IP. Obtain images from authorized service sources or the original manufacturer. Avoid random “dumps” unless you understand the risks and provenance.

Possible disclaimers or additional notes
- Blind resets carry risk when the panel is unreadable. Prefer UART logging so you’re not operating blind.
- Do not short the EEPROM or random pads in an attempt to “force defaults”; use a proper programmer and backups.

Suggestions for further research
- Look up the board barcode and panel code stickers on your MB181TC; they determine the exact firmware/profile you need.
- Identify your remotes by model number; confirm they are correct for JVC‑Vestel, not for another Vestel brand.

Brief summary
- Most probable root cause: IR protocol/keymap mismatch or hotel/IR lock in the NVM/profile, not a bad IR board.
- Easiest confirmations: try a universal remote with JVC‑Vestel and Vestel NEC profiles; watch UART logs for IR events.
- Most reliable fixes without a display: USB emergency profile refresh to the correct JVC MB181 package; if needed, NVM reset with backup.

Questions for the user
- What are the exact model numbers on your two “Vestel” remotes?
- Can you share photos of the MB181TC board stickers (board barcode and panel code)?
- Do you have access to a USB‑TTL adapter (3.3 V) to read boot logs?
- Are you able to try a universal remote (or a programmable one) with alternative code sets for JVC and Vestel?

asenikonomov301 wrote:

The first Vestel remote is from the OEM brand Horizon that works on another TV with the same board - MB181TC, the second one is from another JVC- Vestel with 17MB186TC. Yes, I will be able to upload pictures in a future reply. I do not have a USB_TTL adapter right now but I might order one. I can try using apps like Mi Remote on a phone with an IR blaster. Also I am pretty sure that sources can be changed with the knob, also holding it down just powers off the set.

Initial assessment update
Your new details narrow it down:
- Two handsets known-good on other Vestel sets (Horizon on another 17MB181TC; JVC handset from 17MB186TC).
- Local joystick works (can change sources) and long‑press powers off.
- Panel is broken (you can’t see OSD), LVDS disconnect doesn’t change behavior.
Most probable: the board is running a profile that either (a) expects a different IR code set than your remotes, or (b) has IR/Hotel restrictions active. Hardware in the IR path is very unlikely given POWER works and you’ve swapped the IR board.

Direct recommendation (action plan for your case)
- First, use a phone IR‑blaster app to quickly find a working code set (diagnoses “code mismatch” vs “lock/firmware” in minutes).
- If you find a working set, you can enter service/hotel menus and/or perform a factory reset. If none work, plan for UART (USB‑TTL) and/or a USB profile refresh.
- Because the panel is dead, prefer methods that don’t require on‑screen feedback: audio cues, LED behavior, UART logs.

Detailed problem analysis
- Why only POWER works: On Vestel MB18x, POWER is handled by the standby/boot domain, which “listens wide” so any common Vestel code can wake/sleep the set. After boot, the OS enforces the configured brand profile (IR protocol/keymap). If your handset doesn’t match that profile, non‑POWER keys are ignored. Hotel/Public/Keyboard‑lock modes can also block most IR keys while leaving POWER allowed.
- Your two handsets: Same hardware family ≠ same IR profile. Horizon (MB181) and JVC (MB186) often use different NEC variants/keymaps. POWER overlaps; others don’t.

Tests you can do now (no extra tools)
1. Quick handset sanity
- Camera test: verify every key on both remotes emits IR (view through smartphone camera).
- Disconnect any front‑button keypad if present (only the joystick is connected on many JVC/Vestel, but if there’s a separate key PCB, a stuck key can mask IR).

2. Phone IR app (Mi Remote or equivalent with IR blaster)
- With TV ON (sound playing from HDMI), add and test these brands in order:
- JVC (try all variants offered), Vestel, Toshiba, Hitachi, Finlux, Telefunken, Bush/Technika, Sharp (Vestel builds).
- For each profile press, in this order: Mute → Vol+ → Vol− → Menu → OK → digits.
- Success criteria without a picture: you hear HDMI audio mute/unmute or volume change. If any profile controls audio, you’ve proven a code‑set mismatch.
- If you find a working profile, keep that virtual remote handy; it will let you do resets/menus.

3. HDMI‑CEC workaround (if you have a CEC‑capable source: Fire TV, Roku, PS4/PS5, etc.)
- Enable CEC on the source. Use its remote to navigate the TV (CEC often gives you Up/Down/OK/Back).
- Goal: reach Settings → System → First Time Installation/Factory Reset (names vary). This often clears hotel/IR locks. Do it “blind” by counting key presses, or use the phone IR once you find a matching profile.

4. Differentiate “mismatch” vs “lock”
- If one phone profile can adjust volume but MENU/SETTINGS still don’t respond, hotel/public mode is likely active. If none of the profiles can even change volume, plan on firmware/profile repair.

If/when you get a USB‑TTL (recommended)
- Interface: 3.3 V TTL only (CP2102/FT232/CH340 at 3.3 V). Typical 115200 8N1. Look for a 3–4 pin header marked UART/JP… on 17MB181TC; pin order is usually GND–TX–RX–VCC (verify before connecting).
- What to look for: kernel/daemon messages when pressing remote keys. If logs show IR events tagged “unknown/ignored” → keymap mismatch; if only POWER is logged → hotel restriction or wrong IR driver/profile.
- With shell access (if available on your build), you can trigger a factory reset or clear hotel flags; otherwise it’s still invaluable for confirmation.

Firmware/profile refresh without a working display
- USB auto‑update is standard on MB181/MB18x, but the exact trigger differs by brand build:
- Common method: copy the MB181 package (boot + main + profile files) to a FAT32 USB root; with TV in standby, hold OK on the remote while powering ON until the LED pattern changes, then wait 5–15 minutes.
- Alternative on some builds: insert USB, press and hold the mainboard joystick center while applying AC until fast LED blinking starts, then wait for completion.
- What you need to prepare correctly:
- Exact JVC model identifier from the back label.
- Board barcode and panel code stickers from the 17MB181TC (photos you offered to upload).
- Use matching firmware/profile; wrong packages can soft‑brick or leave IR mis‑mapped.
- Goal: refresh the software profile (includes IR type/keymap) and clear hotel/NVM flags.

Hardware sanity checks (optional but quick)
- IR board supply: measure +5V_STBY at the IR board; check IR signal line at the mainboard connector with a scope. You should see clean bursts for every key, not just POWER. If you only see activity for POWER across two remotes, both remotes are on the wrong code set for this TV.
- IR demodulator type: ensure the IR board uses a 38 kHz receiver (typical Vestel). A 56 kHz module will be unreliable; however, since POWER works with two different boards, this is unlikely the root cause.

Practical guidelines (blind operations you can try if a phone profile works)
- Enter service (for many Vestel builds): MENU then 4725 (needs a working MENU and digits).
- Factory reset: look for “First Time Installation” in the normal menu. If you can’t see, rely on audio cues and consistent key sequences, or use CEC to get there.

What photos to upload (to pick the right firmware/profile)
- Full 17MB181TC board, especially the white barcode sticker(s).
- Panel sticker/code on the metal chassis (even if the panel is broken).
- The IR/LED board part number (helps confirm 38 kHz type).
- The exact model numbers printed on both remotes.

Brief summary
- Your symptoms fit a Vestel IR profile mismatch or hotel lock rather than hardware failure.
- Use a phone IR app to find a code set that changes volume; if found, use it to reset/unlock. If none work, plan for UART logging and/or a USB profile refresh using the correct JVC MB181 package.
- Once IR is mapped correctly or locks are cleared, all keys will work like on your other MB181 set.

Questions for you
- After trying Mi Remote, which brand profile (if any) could change volume/mute?
- Can you post clear photos of the MB181TC stickers and the TV’s rear model label?
- Do you have a CEC‑capable HDMI source available to attempt a blind factory reset?
- If you decide to get a USB‑TTL, confirm it’s 3.3 V; I’ll guide you to the UART header on your board revision.