No Sound Problem; Standby On/Off Problem; No Sıgnal Problem - VESTEL MB120 DS Service Manual

F. NO SOUND PROBLEM
Problem: No audio at main TV speaker outputs.
Check supply voltages of 24V_VCC, VDD_AUDIO_MAIN and 3.3V_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.
G. 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 RJ12 service socket for terraterm
connection.
H. NO SIGNAL PROBLEM
Problem: No signal in OPS mode.
Check OPS supply voltage 12V_VCC/STBY and OPS_STBY(according to power board). Check PS_ON
signal(R1039) while OPS is being started. A pulse width present on the PS_ON shall be detected and responded
within 200 ms to ensure successful operation. Check PWR_STATUS signal (R1040); it must be low if
Pluggable board is power on state. There may be a SW problem, try to update product with latest SW.
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