I just bought a GF-777z which cosmetically was almost flawless, with no cracks or major scratches. Unfortunately, I cannot say the same thing about the functionality of the controls and other things of the box. I noticed the left cassette deck sounds really muddy and low. The right one plays a little better but it’s not as good as other GF-777Z’s I’ve listened to in the past. I’ve cleaned the tape heads with a q-tip and alcohol but that did not improve the sound. Not sure what else I can do about this one, any suggestions?

The other thing I noticed is the treble does not seem to be working the way it should. I turn the knob but it does not do much except slightly from the woofers. I don’t hear any of the highs at all from the radio at all. What could be this problem?

The last that I noticed, when the radio is on FM it does not receive FM Stereo; meaning the Stereo light does not stay on. Only for a brief second when I’m tuning through stations it would maybe flash on. Any suggestions?
Any help on these topics would be much appreciated, and if and when I get these problems fixed I’ll share with you all what was done.


Thank you,

DRVUMAD

Sounds like this box is going to need a lot of work. All are doable, but you are going to need to be persistent to get 'er working to it's potential. Firstly, the muddy sound you are hearing from the tape deck suggests to me that the heads need to be demagnetized. Metallic bits from years of tape use accumulates on the heads and they need to be cleaned off, and the head demagnetized or it can permanently damage your tapes by erasing the highs. Secondly, the FM not receiving in stereo could be several things. But if you are getting good reception in mono but not stereo, then the multiplex pilot signal needs adjusting. That signal needs to be centered at 19khz. The proper way is to adjust it using a frequency counter hooked up to a test point on the tuner board but you can improve it by feel. Lastly, if the treble isn't doing what it's supposed to, it could be as simple as the control itself oxidized or dirty, or it could be worn, or you could have a problem with some defective components in the tonal circuit. If you are technically or mechanically inclined, you might be able to tackle these but if you are not, you might be better off letting someone else tackle this for you. If you want to try this, the first order of business would be to procure a service manual. That manual will be very helpful in disassembly, finding the 19khz test and adjustment points, etc. Also, pick up a good tape head demagnetizer. I recommend the TDK cassette cartridge variety. It's the easiest and safest to use.

Good luck.

Wow, Stormin, thank you for all your advice. I just got the service manual and I opened up the box and found the problem why I was not hearing the treble. I discovered the two outer speakers are inter connected with both tweeters. Those speaker wires which are black, yelow, and white come to a plug that which is CNS802 according to the service manual. That plug was loose for some reason. Once I connected it all those speakers came to life and now I hear the highs that I should have been hearing. I agree with you about the controls, I noticed there is a lot of static when I adjust the volume, treble, bass and especially the band selector. I will get to the POTs and spray them with cleaner and hopefully clear that up. I will also look into getting a demagnetizer and see if that works. I also noticed today sometimes the FF and RR don't work. I'm guessing it has to do with the belts which I think I'm going to replace.

The FM stereo is where I'm a little hazy on. The FM radio comes in great in mono but not in stereo. So I'm taking your advise and I'm going to look into adjusting the multiplex pilot signal. I just don't know where would be the best test point for doing that. Have you tried that before?

Thank you again!

Boomboxman: Yes, I do it all the time. However, I do the adjustment with a frequency counter. The specs call to adjust for 19khz +/- 100hz. Obviously, without a frequency counter, you won't know when you're there since that is a very exacting spec. However, if you tune to a stereo station and adjust according to the manual (without a frequency counter), you should be able to get the stereo indicator to light. Turn further and you'll note the lamp will extinguish. The center point is where you'll want to be. The problem is that you can only adjust using this method when the tuner is tuned to a strong FM multiplex station which makes the pilot signal stronger. I normally make the adjustment at a quiet spot on the tuner dial and so the only way to adjust the pilot signal is with a frequency counter. If you've got the pilot signal adjusted correctly with NO received stations, you'll capture multiplex on strong signals too. Not necessarily true the other way around. However, once again, in the absence of a frequency counter, most users find this "feel" method close enough for their liking.

On your particular model, you'll want to refer to page 18 of the service manual. The 2 steps indicated at the bottom of the page is what you want to do. The adjustments are R21 and R27. Looks like the Sharp GF-777 has 2 seperate steps to accomplish this since it requires the 19khz setting to be correct first, then the LED lighting level is adjusted next. If you don't have a frequency counter, you'll probably have to improvise and adjust R27 to try to center the pilot signal first and hope that R21 is adjusted correctly since you will be doing it backwards and if you follow the instructions according to the manual, you won't have the indicator to guide you.