Lm3886 is quite hard to kill, physically i see no damage. Trace the problem, service manual can help. Its not terrible, you just need patience. For LM3886 'T' use insulating washer with bush(it's better than TF package).
Service manual!? They still make those?
I've made a few discoveries. By squinting through the vent holes in the bottom of the chassis I've been able to trace the mute pin to a resistor halfway across the board. Both mute pins are connected to V- via 6k8, so it's to sourcing ~5mA. Mute current is sufficient, but I'm wary of the fact that the mute pin voltage is positive relative to the ground pin on the LM3886, suggesting that the chip is fried.
I had a chat to an engineer at IAG UK who suggested I check the speaker output relay. He didn't have any idea about the LM3886's used or the mains voltage selector, but he was helpful nonetheless. He seems to think that the 230V volt model should be fine on 240V, but the jumper is there and the transformer is clearly labelled as having two input voltage options; "0-230-240V" and has three corresponding wires. My guess is they want to get the max power out of the LM3886 so they run it as close as possible to its max supply voltage.
The speaker output relay is always energised. Since the bottom of the board is inaccessible I can only tell by the voltage on the surface mount flyback diode. I'm assuming it is meant to be this way and breaks contact when a DC fault is detected, it's hard to say because I can't check the poles of the relay. One day when I lift the board out all of its mysteries will be uncovered!
I've made a few discoveries. By squinting through the vent holes in the bottom of the chassis I've been able to trace the mute pin to a resistor halfway across the board. Both mute pins are connected to V- via 6k8, so it's to sourcing ~5mA. Mute current is sufficient, but I'm wary of the fact that the mute pin voltage is positive relative to the ground pin on the LM3886, suggesting that the chip is fried.
I had a chat to an engineer at IAG UK who suggested I check the speaker output relay. He didn't have any idea about the LM3886's used or the mains voltage selector, but he was helpful nonetheless. He seems to think that the 230V volt model should be fine on 240V, but the jumper is there and the transformer is clearly labelled as having two input voltage options; "0-230-240V" and has three corresponding wires. My guess is they want to get the max power out of the LM3886 so they run it as close as possible to its max supply voltage.
The speaker output relay is always energised. Since the bottom of the board is inaccessible I can only tell by the voltage on the surface mount flyback diode. I'm assuming it is meant to be this way and breaks contact when a DC fault is detected, it's hard to say because I can't check the poles of the relay. One day when I lift the board out all of its mysteries will be uncovered!
