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How to enter the service mode troubleshooting - VESTEL 17MB97 IDTV
The MxL661 is a highly integrated low-power silicon tuner IC that targets all global and digital cable standards. Broadband input filtering and channel filtering have been completely integrated on-chip. This integration enables a compact design resulting in small footprint, low Bill-Of-Material (BOM) cost, and low-power consumption.
Tuning range from 44MHz to 1002MHz
Programmable channel bandwidths of 6, 7, and 8MHz
Integrated channel filtering
Low power consumption with 3.3V and 1.8V dual-supply operation - 351 mW (digital terrestrial)
On-chip voltage regulator enables single supply 3.3V operation
Programmable IF frequency and IF spectrum inversion
Programmable RF to IF delay for ATV scrambling systems that relies on the H-Sync method
Optioanl balun-less application note for cost-sensitive applications
Reference clock output available for re-use by demodulators and additional tuners in multi-channel applications
Input power reporting
Open-drain General Purpose Output GPO available for controlling off-chip circuitry
I2C compatible digital control interface
RoHS compliance.
Troubleshooting
No Backlight Problem
Problem: If TV is working, led is normal and there is no picture and backlight on the panel.
Possible causes: Backlight pin, dimming pin, backlight supply, stby on/off pin
BACKLIGHT_ON/OFF pin should be high when the backlight is ON. Collector pin of Q27 must be low when the backlight is OFF. If it is a problem, please check Q27 and the panel cables. Also it can be tested in TP87 in main board.
Dimming pin should be high or square wave in open position. If it is low, check S248 for Mstar side and panel or power cables, connectors.
Backlight power supply should be in panel specs. check Q43, also it can be checked TP65.
STBY_ON/OFF should be low for TV on condition, check Q36s collector.
CI Module Problem
Problem: CI is not working when CI module inserted.
Possible causes: Supply, suply 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.
Staying in Stand-by Mode
Problem: 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.
IR Problem
Problem: LED or IR not working
Check LED card supply on MB97 chassis.
USB Problems
Problem: USB is not working or no USB Detection.
Check USB Supply, It should be nearly 5V. Also USB Enable should be logic high.
No Sound Problem
Problem: No audio at main TV speaker outputs.
Check supply voltages of 12V_VCC, VDD_AUDIO and 3V3_AMP 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.
Standby On/Off Problem
Problem: Device can not 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 Problem
Problem: No signal in DVB-T/T2/C mode. Check tuner supply voltage; 3V3_TUNER and VDD_1V8. Check tuner options are correctly set in Service
menu. Check AGC voltage at IF_AGC pin of tuner.
Problem: No signal or Low signal in DVB-S/S2 mode.
Check signal cables and LNB voltage, if there is no problem, check RS6000 supply voltages; 3V3_SAT_VDDA1, 3V3_SAT_VDDA, 3V3_SAT_VDD and 3V3_SAT_VCC. If the above measurements are OK, then measure the voltage from the PIN1 of U90. If the PIN1 voltage is equal to 0V, please check i2c waveforms and software. If the PIN1 voltage is lower than 1V(e.g: 0.8Vor 0.3V), change the U90 with a new part.
SERVICE MENU SETTINGS
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.
MAIN AMPLIFIER (U62)(6-8-10 W option)
AD82587D is a digital audio amplifier capable of driving a pair of 8 ohm, 20W or a single 4ohm, 40W speaker, both which operate with play music at a 24V supply without external heat-sink or fan requirement. Using I2C digital control interface, the user can control AD82587Ds input format selection, mute and volume control functions. AD82587D has many built-in protection circuits to safeguard AD82587D from connection errors.
The AD52010 is a 3.0W stereo, filter-less class-D audio amplifier. Operating with 5.0V loudspeaker driver supply, it can deliver 3.0W output power into 4 ohm loudspeaker within 10% THD+N or 2.6W at 1% THD+N. The AD52010 is a stereo audio amplifier with high efficiency and suitable for the notebook computer, and
portable multimedia device.
The AD22657B is a 2-Vrms cap-less stereo line driver. The device is ideal for single supply electronics. Capless design can eliminate output dc-blocking capacitors for better low frequency response and save cost. The AD22657B is capable of delivering 2-Vrms output into a 10k ohm load with 3.3V supply. The gain settings can be set by users from 1V/V to 10V/V externally. The AD22657B has under voltage protection to prevent POP noise. Build-in shutdown control and de-pop control sequence also help AD22657B to be a pop-less device.
The AD22657B is available in a 10-pin MSOP package.
POWER STAGE
Power socket is used for taking voltages which are 12V_stby and 24V (VDD_Audio for 10W option). These voltages are produced in power card. Also socket is used for giving dimming, backlight and stand-by signals with power card.
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Reparatii tv !
tel.0729346286
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