The volume, channel characters add and subtract, the menu is diablo, images, sound normal. DhHservice manual download site
Character has a problem, is obviously character input and output signal processing circuit has a problem. DhHservice manual download site
Measure voltage output IC1101 112.113.114. Feet, press the volume button, a 0.4 V voltage is normal, measuring IC1309 3.4.5 feet, character input voltage is 8 V with normal voltage 5 V of obviously on the high side, so IC1309 suspicion is very large, replacing IC1309 after normal. DhHservice manual download site
IC1309 (for character driven), no character or character can check IC1309 waveform or voltage.DhHservice manual download site