SHARP GF-777Z (LEFT CHANNEL/SPEAKERS )FADES IN & OUT-HELP!!!

[mnb831]

I just got a Sharp GF-777Z and it looks like it's been sitting around for a while. The problem I have is the left channel /speakers wont come on unless I crank it up high. When they do come on there's alot of static. I opened it up and tested the speakers when I switch around the speaker wires which comes from the white plug that goes to some circuit board. The speakers sound great so I know they're not toast. I noticed when I plugged in my headphones in the jack the left side was still out but would not come on even when I cranked it up. I take out the headphones and it seems that the vibration from the right channel kicks on the left channel when I crank it up. Volume and balance control seems to work fine. Could it be some loose connection, cleaning or a dry joint on the circuit board? This is new to me but im quite handy and im willing to take on the task. I've been waiting to get this radio back after 25 years and I want to bring it back to working properly. Thanks in advance for your expertise.

 

[Jboogie2384]

Sounds like a job for DEOXIT! Unplug radio, remove the volume knob and spray a generous amount of deoxit into the actual pot. Try and turn the knob while it's still wet. Let dry and plug radio back up and try the volume knob again. Do this to any and all knobs that make a scratchy sound while being turned when the radio is on. I too have a 777 and a 767 that needed this done and it did the trick. Good luck with yours.

 

[baddboybill]

aboard. You for sure got yourself a beautiful 1st bbx. The problem your having can be a number of different things. The 1st thing you should try and do is pick yourself up some tuner/ pot cleaner, deoxiting spray from an electronics parts store. This is used to help clean your switches and pots from ages of sitting unused. It's always best to take the switches and pots apart to clean real good but if you get this spray you should be able to do this with only taking the chassis out from box. This unit only has a few screws holding it in place but you must unplug some of wire connectors. I would also suggest take lots of pics and write info down so you can get it back together properly
After you have the chassis out then you can start spraying a small amount of spray into the inside of switches and pots through small openings. After you spray you will need to work each one fully back and forth many times to clear up any dust, dirt, and oxidation. When completed you can reassemble and test. After you try this if it does not correct problem you can ask for more info. Most likely this will fix problem because if you at least get something from that channel I highly doubt it's the amp/ preamplifier .. Good luck

 

[mnb831]

Thanks alot gang...I'll try doing that and give you guys an update on the outcome. By the way I also use to own the Conion c- 100 f (GOLD) that I picked up here in NYC over 20 years ago...Best radio I ever had besides the gf-777..It kills me to know how I let it go back then..Oh well...maybe one day....Thanks again..

 

[mnb831]

Sounds like a job for DEOXIT! Unplug radio, remove the volume knob and spray a generous amount of deoxit into the actual pot. Try and turn the knob while it's still wet. Let dry and plug radio back up and try the volume knob again. Do this to any and all knobs that make a scratchy sound while being turned when the radio is on. I too have a 777 and a 767 that needed this done and it did the trick. Good luck with yours.

Thanks alot bud...I'll let you know the outcome, hopefully this'll do the trick..

 

[mnb831]

aboard. You for sure got yourself a beautiful 1st bbx. The problem your having can be a number of different things. The 1st thing you should try and do is pick yourself up some tuner/ pot cleaner, deoxiting spray from an electronics parts store. This is used to help clean your switches and pots from ages of sitting unused. It's always best to take the switches and pots apart to clean real good but if you get this spray you should be able to do this with only taking the chassis out from box. This unit only has a few screws holding it in place but you must unplug some of wire connectors. I would also suggest take lots of pics and write info down so you can get it back together properly
After you have the chassis out then you can start spraying a small amount of spray into the inside of switches and pots through small openings. After you spray you will need to work each one fully back and forth many times to clear up any dust, dirt, and oxidation. When completed you can reassemble and test. After you try this if it does not correct problem you can ask for more info. Most likely this will fix problem because if you at least get something from that channel I highly doubt it's the amp/ preamplifier .. Good luck

Thanks alot Buddy...I'll give it a shot and hopefully get results...I 'll let you know the outcome.. Good Luck..

 

[mnb831]

aboard. You for sure got yourself a beautiful 1st bbx. The problem your having can be a number of different things. The 1st thing you should try and do is pick yourself up some tuner/ pot cleaner, deoxiting spray from an electronics parts store. This is used to help clean your switches and pots from ages of sitting unused. It's always best to take the switches and pots apart to clean real good but if you get this spray you should be able to do this with only taking the chassis out from box. This unit only has a few screws holding it in place but you must unplug some of wire connectors. I would also suggest take lots of pics and write info down so you can get it back together properly
After you have the chassis out then you can start spraying a small amount of spray into the inside of switches and pots through small openings. After you spray you will need to work each one fully back and forth many times to clear up any dust, dirt, and oxidation. When completed you can reassemble and test. After you try this if it does not correct problem you can ask for more info. Most likely this will fix problem because if you at least get something from that channel I highly doubt it's the amp/ preamplifier .. Good luck

Well I went as far as cleaning the entire box inside including taking all the switches and pots apart and giving them a good cleaning.I made fresh cuts and resoldered all speaker wires. I assembled it, turned it on, and the left channel came on for about 5 seconds then nothing..I cant get it to come on even with raising the volume. Where else can I go with this..You mentioned something about the amps..How can I go about locating and checking them .Or, do you suggest trying something else.. Thanks again mnb831...

 

[Jboogie2384]

aboard. You for sure got yourself a beautiful 1st bbx. The problem your having can be a number of different things. The 1st thing you should try and do is pick yourself up some tuner/ pot cleaner, deoxiting spray from an electronics parts store. This is used to help clean your switches and pots from ages of sitting unused. It's always best to take the switches and pots apart to clean real good but if you get this spray you should be able to do this with only taking the chassis out from box. This unit only has a few screws holding it in place but you must unplug some of wire connectors. I would also suggest take lots of pics and write info down so you can get it back together properly
After you have the chassis out then you can start spraying a small amount of spray into the inside of switches and pots through small openings. After you spray you will need to work each one fully back and forth many times to clear up any dust, dirt, and oxidation. When completed you can reassemble and test. After you try this if it does not correct problem you can ask for more info. Most likely this will fix problem because if you at least get something from that channel I highly doubt it's the amp/ preamplifier .. Good luck

Well I went as far as cleaning the entire box inside including taking all the switches and pots apart and giving them a good cleaning.I made fresh cuts and resoldered all speaker wires. I assembled it, turned it on, and the left channel came on for about 5 seconds then nothing..I cant get it to come on even with raising the volume. Where else can I go with this..You mentioned something about the amps..How can I go about locating and checking them .Or, do you suggest trying something else.. Thanks again mnb831...

Well I have a set of amp chips . But make sure that that's what you need before dissecting those kinda parts . If you need them for sure PM me and we can talk. Jr.

 

[mnb831]

aboard. You for sure got yourself a beautiful 1st bbx. The problem your having can be a number of different things. The 1st thing you should try and do is pick yourself up some tuner/ pot cleaner, deoxiting spray from an electronics parts store. This is used to help clean your switches and pots from ages of sitting unused. It's always best to take the switches and pots apart to clean real good but if you get this spray you should be able to do this with only taking the chassis out from box. This unit only has a few screws holding it in place but you must unplug some of wire connectors. I would also suggest take lots of pics and write info down so you can get it back together properly
After you have the chassis out then you can start spraying a small amount of spray into the inside of switches and pots through small openings. After you spray you will need to work each one fully back and forth many times to clear up any dust, dirt, and oxidation. When completed you can reassemble and test. After you try this if it does not correct problem you can ask for more info. Most likely this will fix problem because if you at least get something from that channel I highly doubt it's the amp/ preamplifier .. Good luck

Where are these amp chips located in the radio? And how can I test them? Thanks..mnb831


Never mind... .. I got it working....I found a dry joint on a circuit board near the amp chips somewhere..A little soldering and I'm back in business..I also replaced all the belts in the tape decks this week. This box sounds great now...Thanks again Friend........
mnb831

 

[beverlyjean2]

Be sure connections on headphone and EXT Speaker Jacks are clean and that there are no bad solder joints where they are attached. External speakers when used, disconnect internal speakers. It is important that these jacks be clean so that they can make a proper contact when no external connections are made. They are just like a switch, closing and enabling internal speakers to play. If they are dirty or corroded the increased power of a higher volume setting can sometimes punch through the gunk and allow intermittant operation.