Vestel 17Mb70 LCD TV board – How to enter the service mode, troubleshooting firmware update and more

Used with Vestel 32PF7017, Finlux 42FLHDF850U, JVC LT42TG30J, Sharp LC40LE531E PTP, Vestel Smart TV 42PF7017 and many other models LCD TVs

17MB70-2 main board is based on Broadcom concept IC. This IC combines DVB-T COFDM terrestrial and PAL/SECAM demodulators, HDMI receivers, a transport processor, a digital audio processor, graphics processing, Ethernet MAC and PHY, digital processing of analog video and audio, analog video digitizer and DAC functions, stereo high-fidelity audio DACs, a 400-MHz dual-threaded MIP processor, and a peripheral control unit providing a variety of television control functions. This IC also features an advanced video decoder capable of supporting high-definition AVC, VC-1, and DVB-T MPEG-2 streams.

Tuner FT 2112/3/8/9 are newly developed Half-NIM modules designed for both digital (DVB-T / T2 and DTMB for terrestrial China) and analog TV reception in compliance with

the European ATV standards for analogue, as well as with the terrestrial standard ETS 300 744 for DVB-T and the new terrestrial standard ETS 302 755 for DVB-T2. It consists of a 3- band RF tuner, which receives RF signal and down-converts it to an IF frequency of 36MHz for digital and 38.9MHz for analog IF. The analogue IF output can directly drive a SAW filter. A digital IF Stage, which consists of one SAW filter & gain-controllable IF that offers a sufficient output level to be connected directly to an A/D converter.

In active antenna option, the following circuit is used. ANT_CTRL pin is controlled by microcontroller. If ANT_CTRL is low, ANT_PWR will be low. If ANT_CTRL is high,
ANT_PWR will be high. OVER_CUR_DETECT pin is a monitor for short circuit in antenna.  OVER_CUR_DETECT is low, ANT_CTRL will be low, so ANT_PWR will be low. Finally, short circuit protection is done by circuits and micro-controller.

MAIN AMPLIFIER (TPA3110)

17MB70 uses TPA 3110 15-W filter-free stereo Class-D audio power amplifier for main audio output. The TPA3110D2 is a 15-W (per channel) efficient, Class-D audio power
amplifier for driving bridged-tied stereo speakers. Advanced EMI Suppression Technology enables the use of inexpensive ferrite bead filters at the outputs while meeting EMC
requirements. Speaker Guard speaker protection circuitry includes an adjustable power limiter and a DC detection circuit. The adjustable power limiter allows the user to set a "virtual" voltage rail lower than the chip supply to limit the amount of current through the speaker. The DC detect circuit measures the frequency and amplitude of the PWM signal and shuts off the output stage if the input capacitors are damaged or shorts exist on the inputs.

The TPA3110D2 can drive stereo speakers as low as 4 Ω. The high efficiency of the TPA3110D2, 90%, eliminates the need for an external heat sink when playing music. The
outputs are also fully protected against shorts to GND, VCC, and output-to-output. The short-circuit protection and thermal protection includes an auto-recovery feature.

The TPA3112D1 is a 25-W efficient, Class-D audio power amplifier for driving a bridge tied speaker. Advanced EMI Suppression Technology enables the use of inexpensive ferrite bead filters at the outputs while meeting EMC requirements. Speaker Guard speaker protection system includes an adjustable power limiter and a DC detection circuit. The adjustable power limiter allows the user to set a "virtual" voltage rail lower than the chip supply to limit the amount of current through the speaker. The DC detect circuit measures the frequency and amplitude of the PWM signal and shuts off the output stage if the input capacitors are damaged or shorts exist on the inputs. The TPA3112D1 can drive a mono speaker as low as 4Ω. The high efficiency of the TPA3112D1, > 90%, eliminates the need for an external heat sink when playing music. The outputs are fully protected against shorts to GND, VCC, and output-to-output. The short-circuit protection and thermal protection includes an auto recovery feature.

SATELLITE RECEIVER (Broadcom)

The BCM4505 is a fully integrated satellite receiver single-chip solution targeted at multituner advanced modulation satellite receiver systems and ideally suited for new generation satellite receivers and integrated multifunction Home Media Centers. The BCM4505 integrates a CMOS tuner and advanced modulation decoder supporting DVB-S2 Broadcast, DVB-S, DIRECTV, and 8PSK Turbo applications. The highly integrated tuner section is based on existing volume-production Broadcom technologies and a direct conversion technology to reduce external components and increase performance. The BCM4505 is designed to support the full 1-45 Msps DVB operating range with support for
250 to 2150 MHz input frequencies. It contains two 8-bit A/D converters, all-digital variable rate QPSK/8PSK receivers, an advanced modulation LDPC/BCH and Turbo FEC decoder, and a DVB-S compliant FEC decoder. All required RAM is integrated and all required clocks are generated on-chip from a single reference crystal. The baseband IQ analog waveforms from the tuner section are sampled by the integrated 8-bit A/D converters and resembled by the integrated interpolative digital filter banks.  Optimized soft decisions are then fed into either a DVB-S-compliant FEC decoder, or an advanced-modulation DVB-S2 LDPC/BCH or Turbo decoder. The final error-corrected output is delivered in MPEG-2 transport format. The output clock is generated by an on-chip PLL for low-jitter operation and glue less integration with Broadcom's high definition audio video subsystems, such as the BCM7401 and the BCM7402. The communication link sections include an on-chip microcontroller for all system configuration, acquisition, control, monitoring and diagnostics functions, as well as an integrated DiSEqC 2.x controller for 2- way communication with an LNB, and a single FSK transceiver for communication with ODUs that support multiple LNB configurations over a single coax connection. The BCM94505 reference design is available for easy system design and testing using the BCM4505 advanced modulation receiver chip.

Problems and solutions

Staying in Stand-by Mode [Staying in stand-by mode, no other operation]

This problem indicates a short on Vcc voltages. Protect pin should be logic high while normal operation. When there is a short circuit protect pin will be logic low. If you detect logic low on protect pin, unplug the TV set and control voltage points with a multimeter to find the shorted voltage to ground. 

LED or IR not working

Check LED card supply on MB70 chassis.

Keypad or Touchpad is not working

Check keypad supply on MB70.

USB is not working or no USB Detection.

Check USB Supply, It should be nearly 5V. Also USB Enable should be logic high.

No audio at main TV speaker outputs.

Check supply voltages of VDD_AUDIO, 8V_VCC and 12V_VCC with a voltage-meter.  There may be a problem in headphone connector or headphone detect circuit (when

headphone is connected, speakers are automatically muted). Measure voltage at HP_DETECT pin, it should be 3.3v.

Device cannot boot, TV hangs in standby mode.

There may be a problem about power supply. Check main supplies with a voltage-meter. Also there may be a problem about SW. Try to update TV with latest SW. Additionally it is good to check SW printouts via Teraterm. These printouts may give a clue about the problem. You can use Scart-1 for terraterm connection.

No signal in TV mode.

Check tuner supply voltage; 5V_TUN. Check tuner options are correctly set in Service menu.  Check AGC voltage at RF_AGC pin of tuner.

Micro-controller section - schematic

Audio output section schematic

How to enter the service mode

In order to reach service menu, First Press “MENU” button, then write “4725” by using remote controller.
You can see the service menu main screen below. You can check SW releases by using this menu. In addition, you can make changes on video, audio etc. by using video settings, audio settings titles.

Software Update
In MB70 project you can update the main IC software by using USB ports. You can find the SW update procedure below.
1. Software files should copy directly inside of a flash memory(not in a folder).
2. Put flash memory to the tv when tv is powered off.
3. Power on the and wait. TV will power-up itself.
4. If First Time Installation screen comes, it means software update procedure is successful.
5. You can check the SW release name from service menu.

No Backlight Problem
If TV is working led is normal and there is no picture and backlight on the panel.
Possible causes: Backlight pin, Pin 21 of Power socket] dimming pin, backlight supply, stby on/off pin BACKLIGHT_ON/OFF pin should be high when the backlight is ON. R185 must be low when the backlight is OFF. If it is a problem, please check Q131 and the panel cables.

Dimming pin should be high or square wave in open position. If it is low, please check S32 for BRCM side and panel or power cables, connectors.  STBY_ON/OFF_NOT should be high for standby condition, check R203.

Power socket

CI Module Problem [CI is not working when CI module inserted.]

Possible causes: Supply, supply control pin, detects pins, mechanical positions of pins.

CI supply should be 5V when CI module inserted. If it is not 5V please check CI_PWR_CTRL, this pin should be low.

Check mechanical position of CI module. Is it inserted properly or not.

Detect ports should be low. If it is not low please check CI connector pins, CI module pins.