hi ive got a old kenwood reciver the problem is that when I try to use fm or am radio all I hear from my speakers is a very faint sound of the signal.(like when i turn it up i only hear a little bit of sound) even though the signal bar reads a very strong signal and the stereo sound indicator is on.
There could be a dozen possible areas to check from the output transistors in the tuner section to a bad input selector switch. Unless you have the ability to trouble shoot the receiver, it will have to go to a technician. Be aware Kenwood no longer supports the old receivers with parts and not many techs are going to have schematics for the 6400. If you want this done, you will have to use someone who specializes in "vintage audio repair". Put that into a search engine and you should get some places to call. This will not be a cheap repair based on the fact it is vintage and, though the 6400 was not an expensive receiver in the 1970's, you are paying specialist prices today. You might want to consider buying a new outboard tuner if this is important to you or buying a new receiver.