bazarimajom
Member
Recently I got my hands on this amp however when I turn it on the led 4/4 blinks while the others stay lit, with DBT. No input or speakers are connected. The service manual says "DC offset voltage for Right channel exceeds set level". So I checked some voltages on the board KU-9143-3 and found a deviation at IC502 (TLP521-1) which is an optocoupler. At legs 1-2 it should have 72V which is correct but at legs 3-4 there is excessive voltage 43V where it should be 389mV at leg 4 and -1.67v at leg 3. On the other side the voltages are very close to spec (+a slighty lower because of the DBT with 100W bulb). My question is: Is it enough if I change this part only, and what is a suitable replacement part for this? The closest I found was this but I'm not sure if it will be ok. Any suggestions are welcome!