airtech
Well-known member
I'm having a problem with a hum coming from my Ampex MM1100/16track.
The 60hz hum is approximate, but I think pretty close to what I'm hearing.
Here's a real quick (1 minute) test to describe what's happening:
With no tape on the heads and with it powered on of course, I took the arm (under the supply reel) and switched it all the way right so the reels don't spin. I then took all the channel toggles and switched them to ready. In Normal Mode, I here the hum and here popping when switching the sel sync/repro toggle. In Input mode, with all the toggles still in ready mode, there is no popping or humming at all. With all the channel toggles switched to safe, there is hum in the input and normal mode, but no popping when switching and also hum when switching the sel sync/repro toggle and popping as well.
All of the electrolytics on the channel cards have been replaced, but that's it.
And I thought that the problem was isolated to a few channels, but when switching channels from ready to safe mode and back, the problem got gradually worse and better. So I don't think it's a problem with a specific channel.
One other thing, when the hum is there, it gets at least 2-3 time louder when I engage the supply reel by taking the arm and releasing it to the left and the reels spinning away.
With the tape on the heads normally, the situation was the same.
Thanks for any help. I also sent this over to the ampex list for some help as well.
Nate
The 60hz hum is approximate, but I think pretty close to what I'm hearing.
Here's a real quick (1 minute) test to describe what's happening:
With no tape on the heads and with it powered on of course, I took the arm (under the supply reel) and switched it all the way right so the reels don't spin. I then took all the channel toggles and switched them to ready. In Normal Mode, I here the hum and here popping when switching the sel sync/repro toggle. In Input mode, with all the toggles still in ready mode, there is no popping or humming at all. With all the channel toggles switched to safe, there is hum in the input and normal mode, but no popping when switching and also hum when switching the sel sync/repro toggle and popping as well.
All of the electrolytics on the channel cards have been replaced, but that's it.
And I thought that the problem was isolated to a few channels, but when switching channels from ready to safe mode and back, the problem got gradually worse and better. So I don't think it's a problem with a specific channel.
One other thing, when the hum is there, it gets at least 2-3 time louder when I engage the supply reel by taking the arm and releasing it to the left and the reels spinning away.
With the tape on the heads normally, the situation was the same.
Thanks for any help. I also sent this over to the ampex list for some help as well.
Nate