A note about pre-driver transistors on the PL amps.
Oscillation. All the drivers AND pre-drivers were changed to ON Semi MJ15024 devices by the owner. Random wall to wall oscillation was occurring on the lower half of the right channel signal. As you might expect, the upper half was rock solid but not the bottom half. Reverting to the original faster RCA410 pre-drivers fixed this issue. As a sidebar, the entire right channel had the wrong size transistor mounting screws installed, 24 screws of a larger size putting undue stress on the B and E leads going into the socket. 3 of the imitation sil pads were perforated and one of the MJ15024s had a nasty burr around one of the mounting holes.
Things to check for Zach, these are things you run into quite often.
By the way, the screws used to hold the TO-3 transistors in should have a thread major diameter of 0.136-0.140", not the 0.156" I was measuring on the defective screws.
Oscillation. All the drivers AND pre-drivers were changed to ON Semi MJ15024 devices by the owner. Random wall to wall oscillation was occurring on the lower half of the right channel signal. As you might expect, the upper half was rock solid but not the bottom half. Reverting to the original faster RCA410 pre-drivers fixed this issue. As a sidebar, the entire right channel had the wrong size transistor mounting screws installed, 24 screws of a larger size putting undue stress on the B and E leads going into the socket. 3 of the imitation sil pads were perforated and one of the MJ15024s had a nasty burr around one of the mounting holes.
Things to check for Zach, these are things you run into quite often.
By the way, the screws used to hold the TO-3 transistors in should have a thread major diameter of 0.136-0.140", not the 0.156" I was measuring on the defective screws.