donnysparks
Well-known member
Hi all. i'm having some trouble with a module that i've racked. this is my 4th time through racking a pair of these, so i guess i've been lucky to not have had trouble sooner:
the module passes audio only in the first 5 positions of the input gain switch. from the 6th position on the audio disappears. you can still hear a faint (60hz?) hum in the background after the audio is gone, and this gets louder and softer with adjustment of the output pot. the hum is present in all settings.
Initially it would only pass audio in the 3rd through 5th positions. i replaced a transistor that looked suspicious to me and arrived at where i am now. i would go ahead and replace them all but i don't have enough to do it right now. i'm hoping someone might be able to tell by looking at the way the input switch is set up on the schematic:
http://www2.yamaha.co.jp/manual/pdf/pa/english/mixers/PM1000E_2.pdf
also, strangely, when i touch the tops of C10 and C11 i get a buzz. doesn't happen anywhere else...
any ideas? thanks in advance for any help. i'm obviously going to need some beer. be right back!
the module passes audio only in the first 5 positions of the input gain switch. from the 6th position on the audio disappears. you can still hear a faint (60hz?) hum in the background after the audio is gone, and this gets louder and softer with adjustment of the output pot. the hum is present in all settings.
Initially it would only pass audio in the 3rd through 5th positions. i replaced a transistor that looked suspicious to me and arrived at where i am now. i would go ahead and replace them all but i don't have enough to do it right now. i'm hoping someone might be able to tell by looking at the way the input switch is set up on the schematic:
http://www2.yamaha.co.jp/manual/pdf/pa/english/mixers/PM1000E_2.pdf
also, strangely, when i touch the tops of C10 and C11 i get a buzz. doesn't happen anywhere else...
any ideas? thanks in advance for any help. i'm obviously going to need some beer. be right back!