What a timely video- I am working on a 460 with a 48350 that is blowing both 3a fuses. This really helps me understand the amp more as it is my first one to try to fix! Thank you!
Best practice is to replace BOTH heat sink (or driver board) transistors on the same channel if one is found to be shorted. As for your fuse holders, check for shorts AND open sockets on both those bakelite plugs. One thing I omitted in the video is to consider Q9, the supply board transistor, as a cause of noise that varies with the volume......not as common as the other causes of noise I mentioned but easy to replace if fixing the other possible causes doesn't resolve the noise. Best wishes David
@@williamweisel2176 I replaced all four heat sink transistors and NO blown fuses this time! Thanks to your video!! Now R44 on the cap board started smoking! It measured 17k instead of 22 ohms so I have those ordered. All other components on the board is ok and I just miss read the value when I was checking them. Thanks to this video and you again for helping so much. If I cant get it fixed I am sending it to you!
I generally check and replace all components before plugging in the amp........but it sounds like you did that. This amp is modular and fixable and had no output transformers in it......
What a timely video- I am working on a 460 with a 48350 that is blowing both 3a fuses. This really helps me understand the amp more as it is my first one to try to fix! Thank you!
I did find a bad heat sink transistor- Q7 and have ordered another one
Best practice is to replace BOTH heat sink (or driver board) transistors on the same channel if one is found to be shorted. As for your fuse holders, check for shorts AND open sockets on both those bakelite plugs. One thing I omitted in the video is to consider Q9, the supply board transistor, as a cause of noise that varies with the volume......not as common as the other causes of noise I mentioned but easy to replace if fixing the other possible causes doesn't resolve the noise. Best wishes David
@@williamweisel2176 I replaced all four heat sink transistors and NO blown fuses this time! Thanks to your video!! Now R44 on the cap board started smoking! It measured 17k instead of 22 ohms so I have those ordered. All other components on the board is ok and I just miss read the value when I was checking them. Thanks to this video and you again for helping so much. If I cant get it fixed I am sending it to you!
I generally check and replace all components before plugging in the amp........but it sounds like you did that. This amp is modular and fixable and had no output transformers in it......