Help With Mac 1700

[mikiekimi]

With the selector knob set to AUX in front (right now it's on FM Auto), do you get any sound when you send it through the phone? I'd set the remote speaker switch to OFF since you're in main.

 

[mobilestudio]

No sound when I do that. I have also tested with the remote speaker switch set to OFF.

When I said that I tested aux, phono, etc.. it involved operating the unit correctly. I know how to run a wire into aux and then set the dial on the front appropriately. I would not expect sound being inputted to AUX to come out if it were set to FM Auto (I would expect the tuner to come through--which it does not).

I appreciate the help, and I know you're concerned about user error, but I have enough experience to know how to operate a receiver appropriately. Happy to try any other suggestions you may have though.

 

[mikiekimi]

Do you get any sound if you toggle stereo/mono, filter, tape mon, or main speaker? How high is the volume turned up?

Here is a portion of the block diagram from the SM.


If you're getting sound through phono but not tape/aux, then it points to the input selector switch. If you run your phone through Tape and use the Tape Mon switch on the front do you get sound? Looks like Tape Mon (the switch, not Tape on the rotary control) bypasses the input selector control.

 

[mobilestudio]

At this point I'm not getting sound from anything. I have toggled all of them (in all their various permutations) and nothing.

There was a point yesterday that I was getting sound from the tuner and phono, but I'm not getting that at all anymore. This was with the switch configuration I described earlier.

I've got to run into a few meetings but will try running through tape mon later today. I have tried this in the past and still didn't get anything. I was nothing if not thorough.

 

[mikiekimi]

Depending on the results of testing Tape Mon, you can use the block diagram from the SM to trace the signal through all of the controls.

After cleaning all of the controls and making sure they are indeed all functioning properly, you would be at a point where I would be feeding a 1KHz test tone into the receiver and tracing it with an oscilloscope.

Here is the right portion of the block diagram...good luck!

 

[mobilestudio]

Thanks! That might be the point that it's time to take it to a shop for me.

The plot thickens though! I just turned it on again and this time it was working kinda.

Phono 1 and the FM tuner were both providing output, and AUX was creating a LOUD hum (but no signal output).

The big issue now is that phono 1 and the tuner both sound very reedy, the signal is attenuated somehow (and yes I played with the filter switch, it wasn't that--the filter switch attenuated the attenuation ).

Lots of scratchy sounds when I would play with the volume control, especially on the louder end. When I pushed it in as I was playing with it sometimes it would sound a little thicker, but with some weird harmonics.

When I was cleaning the inside I did not clean the volume pot because it was locked away in a case. Maybe I need to try to clean it a little somehow? Maybe it's something else? But it is giving me output now...at least for the time being. It also didn't overheat and shut down after 10 minutes...so who knows.

 

[mobilestudio]

For the true believers out there still following this saga, the receiver was given another short rest and after powering it up this time it just gave me a loud audible hum through the speakers. At this point I'm starting to think that a lot of the fussiness I've experienced with it this past few days is due to components on the inside burning out and dying. I'm going to take it to a shop to get a diagnosis tomorrow.

Thanks everyone for the help. All the suggestions offered were excellent and a lot of fun. This one punches way above my skill though, unfortunately.