Help with AU7900

[Promo]

I have an AU7900 I bought new in 1976. I have been using an Adcom GFP
710 and GFA5500 but wanted to hear what it would sound like to use the AU7900 as a preamp through the GFA5500. Unfortunately, when I use the separation switch on the back and connect Pre Out on Saunsui to the GFA5500 all I get is a loud rumble. Any ideas? Anyone out there willing and able to repair my AU7900? I currently reside in the Toledo, OH area. Any help out there? Feel free to PM me.

 

[EchoWars]

Does it work OK when used as a full integrated?

 

[Promo]

Works perfectly as integrated amp. I'm listening to it right now.

 

[EchoWars]

Ground loop problem maybe?? Dunno...if I heard it maybe I could identify it.

Might also be a dodgy pre/main switch. You might try cleaning it.

 

[bolly]

probably a dirty separation switch. My Kenwood KA-9150 suffered the same(garbled channel), untill EW told me to clean that switch with contact cleaner. :yes:

 

[Promo]

Thanks for your help. I will clean the switch and see if that does it. Everything else works perfectly and frankly, even if I get the pre-amp separated I am not sure I'm going to like it through the Adcom amp as much as I like listening to the AU7900 as an integrated amp.