This cheap LG audio/DVD set turns off by itself after a few seconds of powering on. No sound from speakers in any function (it's possible to switch function while it's on). No DVD mechanism activity.
Voltages check: only +9V is missing. Actually, +9V line is short at Main PCB. This explains absence of DVD mechanical activity. Since I have records of shorted caps in these crappy sets, I begin checking all caps that are in contact with +9V (ACC9V in schematics). Extract [C15] and it's innocent. Extract [C526], same. Extract [C61] (100uF/16V) and it's shorted!!
After replacing it I reassemble and try the set. Now it reads CD/DVD but there's still no sound at all!! It's a TDA7292 based amp. Mute line (A_MUTE) seems OK (0V on play, 2,5V when muting). Audio reaches pins 7 and 11 of TDA7292, but its pin 5 is = +VCC, so this means mute. Should be lower (about 10V) in order to be active.
Check diodes and caps from mute circuit and, OMFG, [CE706] (220uF/35V) is shorted too!!
Both caps are in different boards, different brands, different values, but same crappiness. Replace it and fixed.
Note that actual cap values doesn't match the ones stated in SM.
Edit: I attach Service Manual PDF, since it's not available at ElektroTanya, and I doubt that Pihe will accept it since he rejects anything that says «Confidential», «Internal use only», etc.
Voltages check: only +9V is missing. Actually, +9V line is short at Main PCB. This explains absence of DVD mechanical activity. Since I have records of shorted caps in these crappy sets, I begin checking all caps that are in contact with +9V (ACC9V in schematics). Extract [C15] and it's innocent. Extract [C526], same. Extract [C61] (100uF/16V) and it's shorted!!
After replacing it I reassemble and try the set. Now it reads CD/DVD but there's still no sound at all!! It's a TDA7292 based amp. Mute line (A_MUTE) seems OK (0V on play, 2,5V when muting). Audio reaches pins 7 and 11 of TDA7292, but its pin 5 is = +VCC, so this means mute. Should be lower (about 10V) in order to be active.
Check diodes and caps from mute circuit and, OMFG, [CE706] (220uF/35V) is shorted too!!
Both caps are in different boards, different brands, different values, but same crappiness. Replace it and fixed.Note that actual cap values doesn't match the ones stated in SM.
Edit: I attach Service Manual PDF, since it's not available at ElektroTanya, and I doubt that Pihe will accept it since he rejects anything that says «Confidential», «Internal use only», etc.
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