Sherwood S-7010A Transistor Issue?

[Aethelstan]

Preface: I am an amateur hack with no training or strong knowledge.

The right channel on this works great. The left channel hums at a constant level regardless of volume adjustment. (The pots have been cleaned.) I may be off, but I think I have a bad transistor for a few reasons. The hum reminds me of the bad transistor problem I had on a S-7100. The left 606a and 607a transistors (2SC1419) are different from the right 606b and 607b transistors (2SD330) and there appears to be solder beads on the collector and emitter tines of the left 607b transistor (2SC1419). I am guessing those 2SC1419 transistors were replacements at some point. Further, when I use a multimeter on the collector and emitter tines of the 2SD330 transistors, I get a reading of ~700, but I only get a reading of 1 or 2 from the 2SC1419 transistors. When I use a multimeter on the base and emitter tines of the 2SD330 transistors (606b and 607b), I get a reading of ~450, but on the 607a transistor and I get a reading of ~600 and on the 606a transistor I get a reading of about 115.

Is 606a my problem?

Am I right in thinking that I can replace it with a TIP 41C transistor that I have on hand? The tines appear to be in the same order.

 

[cademan]

 

[Tom B]

you should change both of those 2SC1419 transistors in that channel. Yes you can try using TIP41C transistors. But you may also have problems with the driver transistors, and other transistors and resistors in that channel. Make sure to use a dim bulb tester when powering it up after transistor replacement