I got this beauty in a fairly nice condition. As far as I see almost all transistor/caps was replaced on the amp board, only the 2SD339 power transistors and the bias adjustment transistors left original. Measured & adjusted the bias according to the service manual, it was stable.
First problem was that the right channel was slightly louder than the left. I almost tracked down the issue to the pre-amp board (at least I thought) when suddenly the right channel kicked out the bucket. The right channel's 2SC1539 is gone, the other channel seems to be ok.
Questions is: what would be the proper replacement for 2SC1539, also I assume I should change the 2SC1509?
2SC1509 = maybe BC649-16?
2SC1539 = KSC945?, BC232?
The problem is that the 2SC1509 is SIP3 package or something like this, sitting on the pcb. It's placed between the two 2SD339, but there is a square hole on the heatsink where this transistor comes through. So basically not really thermal coupled with the heatsink, but really close to them, because the heatsink is attached to the pcb and the 2SD339s too.
So if I replace it with a simple TO-92 package type BC os KSC, should I attach it to the heatsink?
The other issue is I'm not sure that this is just accidentally blown up(and that caused the different channel output level) or something screwed up when it was "restored".
One thing I found that the BD139&BD140 has slightly different hfe (like 190 and 300), could be an issue in the future?
The service manual is barely readable, but I marked the original transistors on it with red, blacks are the new.
First problem was that the right channel was slightly louder than the left. I almost tracked down the issue to the pre-amp board (at least I thought) when suddenly the right channel kicked out the bucket. The right channel's 2SC1539 is gone, the other channel seems to be ok.
Questions is: what would be the proper replacement for 2SC1539, also I assume I should change the 2SC1509?
2SC1509 = maybe BC649-16?
2SC1539 = KSC945?, BC232?
The problem is that the 2SC1509 is SIP3 package or something like this, sitting on the pcb. It's placed between the two 2SD339, but there is a square hole on the heatsink where this transistor comes through. So basically not really thermal coupled with the heatsink, but really close to them, because the heatsink is attached to the pcb and the 2SD339s too.
So if I replace it with a simple TO-92 package type BC os KSC, should I attach it to the heatsink?
The other issue is I'm not sure that this is just accidentally blown up(and that caused the different channel output level) or something screwed up when it was "restored".
One thing I found that the BD139&BD140 has slightly different hfe (like 190 and 300), could be an issue in the future?
The service manual is barely readable, but I marked the original transistors on it with red, blacks are the new.
