Pioneer SA-7700

[Baggy]

Hoping someone can steer me in the right direction.
I acquired a SA-7700 (attic find) freebee from neighbor and a set of CS99As (garage sale $30) and LOVE the sound, but.......
With cd player, mp3 player or tape all channels work whether its A or B perfectly but in phono mode the left channel hums and watt needle moves up (showing power to speakers) and on B channel. Right channel works fine. Deoxit? or?

 

[merlynski]

Welcome to AK!
Deoxit is always a good first option, especially on a unit that has been sitting around. Do you have the Service Manual? Download from hifiengine.com, register for free and is safe. Any electronics experience or test equipment?
Looking at the schematic in the service manual shows a 'Phono Interference' switch that is between the phono inputs and the phono amp. That looks like a prime target for deoxit application and switch exercise. The Function (source) switch is also a candidate as that is where the signal paths all come together.
D5 and switch exercise first, then if no improvement dig in further.
Is your turntable 'known good' on a different amp?

 

[Baggy]

Thank you for your help Merlynski. I do have the service manual, multimeter and a bit of electronic repair experience and with your advice I'll be able to get into er. I had taken the unit apart to get the dust blown out, did clean the pots etc then built new sides and top from some exotic hardwood I had kickin' around so it's had a minor upgrade. ;-) I'll let ya know how things turn out. Looking forward to playing some vinyl Floyd and Boston at volume soon! Cheers.

 

[Baggy]

A

 

[Baggy]

Cleaned everything and cycled the switches and Voila.... Left channel is singin'!! Now just waiting to go pick up some CS63DXs to go with the CS99As. Loving the vinyl and actually hearing music for the first time in decades. ANALOG!!!!!