bhuskins
Super Member
I have a G-9000db that was recently discovered and I am attempting to bring it back to its former glory. Everything is going pretty good other than the tuners.
Starting with FM a few issues exist.
- no stereo separation and no stereo indication...confirmed voltage does not make a change when stations are tuned and the mono switch engaged/disengaged makes no change in the signal that can be heard between the mono and stereo modes with headphones worn.
- it does tune fairly clearly from one end to the other of the dial...just not in stereo.
- the FM tuning meter does not center when tuned to a station. I did adjust TO5 to see if I could easily get it to center and it would not. At both extremes (completely in and all the way out) it was close but still nowhere near where it should be. I set it back to where it was originally.
- on AM the tuning meter immediately centers as it should and stays there...only on FM does it deflect to the left. So I speculate the meter is OK and it's the signal it is receiving causing the issue.
A couple things I've noted...
-13.0v on pin 24
-signal meter does reacts to a good signal
-tuning capacitor has been properly cleaned per the sticky (3 times)
Also, when on FM and when tuned to a good station with excellent signal, the stereo performance and indication is like I said above (not working) but something I didn't point out is that when I switch the FM MUTE to on the sound does goes away no mater how well the signal is tuned into the station. So mute is working I assume because the circuit is not receiving the signal to avoid muting.
I actually have NOS replacement ICs on hand for all of the ICs on the tuner board, but I tend to think this is something a little more simple (or complex depending on how you look at it.)
Any thoughts on what to look at?
I didn't mention it but AM is basically not working but I haven't really looked at it that much and figured I would focus on the FM first.
Starting with FM a few issues exist.
- no stereo separation and no stereo indication...confirmed voltage does not make a change when stations are tuned and the mono switch engaged/disengaged makes no change in the signal that can be heard between the mono and stereo modes with headphones worn.
- it does tune fairly clearly from one end to the other of the dial...just not in stereo.
- the FM tuning meter does not center when tuned to a station. I did adjust TO5 to see if I could easily get it to center and it would not. At both extremes (completely in and all the way out) it was close but still nowhere near where it should be. I set it back to where it was originally.
- on AM the tuning meter immediately centers as it should and stays there...only on FM does it deflect to the left. So I speculate the meter is OK and it's the signal it is receiving causing the issue.
A couple things I've noted...
-13.0v on pin 24
-signal meter does reacts to a good signal
-tuning capacitor has been properly cleaned per the sticky (3 times)
Also, when on FM and when tuned to a good station with excellent signal, the stereo performance and indication is like I said above (not working) but something I didn't point out is that when I switch the FM MUTE to on the sound does goes away no mater how well the signal is tuned into the station. So mute is working I assume because the circuit is not receiving the signal to avoid muting.
I actually have NOS replacement ICs on hand for all of the ICs on the tuner board, but I tend to think this is something a little more simple (or complex depending on how you look at it.)
Any thoughts on what to look at?
I didn't mention it but AM is basically not working but I haven't really looked at it that much and figured I would focus on the FM first.
