Sharp GF-777H problems

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tatto

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Feb 11, 2015
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Hi guys! (my english maybe bad, i'm italian and my english is "Highschool Level")
I'm following your threads since my daddy gifted me a wonderfull Sharp gf-777H boombox for birthday. I'm really loving it. The boombox was bought in Lebanon when my father was there for military activities and so it is very dirty and scratched. The boombox was used a lot, on the beach, snow, country and on a bagpack of a pickup too. :thumbsup: It is now 30 old and it's time to give it a second life. The box is working great, (i'm writing this thread with it playing on the background) i used it on the last of the year's eve party as main player and we all were satisfied! I've Cleaned it a lot, i'm taking so much care, like a son! But there are some problems that i'm not able to solve, and so i'm asking your help! I solved some issues like the On/Off switch that didn't kept the ON position. I opened the box, and i have fixed the switch putting a piece of kitchen paper behind the clicker, and it worked like new! Other problems that i've fixed too, were the bass and treble booster control knobs that were hard to move. I've used a deoxeder and lubrifier spray and they are working like new! The right antenna was broken, and because i'm very lucky i've found an indentical antenna in our garage!

Now i need your help, i want to restore this boombox like new! The problems that i can't solve are this:

1. The tape engine is totally f****d! If i press play, rewind ecc. the mechanics are not moving. It doesn't read any cassette. And a really painfull problem, is the PLAY button on the second tape that keeps pressed despite i press STOP! And so my box everytime that i connect it on any type of power source, it goes automatically on playing and if i have to stop the box i have to plug out the power source. I can't use batteries because when they are plugged in, the box keeps on and i can't power it off. This is very sad, i love my box and i'm not an vintage tape mech expert. I could do it but i need somone who helps me!

2. Left VU meter not working. This is important because i need it to check the battery level.

3. The metal grey colors are very eyecandy. But the box was used a lot and so there are a lot of white spots. I want to recolor all the surface and i've found here on the forum two colors that matches with the box: MODEL MASTER 1790, TAMIYA X-M. Are thoose correct?

4. Now i'm using the box connected on a ipod as input. How are cassettes? I know that the gf777 is an HiFi player that supports METAL/CrO2 type tapes. (up to 18000khz fidelty). Can i use it today or will i get only a creepy and scratchy sound like my grandfather's 1WW radio?

5. This is not very important but i want to replace the amps and woofer with something newer, to improve quality. Thoose are working quite well but the woofer don't go lower than 30hz like my father's cool car stereo with 6,5 inch woofers. When the volume is high i have to put the bass knobs to 0 because the woofers blow out a noisy sound.

I'll post some pics later. Thank you, any kind of help is appreciated! sorry for english mistakes ;-)
 

goodman

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Jun 14, 2011
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:hi: to the forum!
How to post images - read this topic:
https://boomboxery.com/forum/index.php/topic/21759-faq-how-to-post-images/

I think, you can fix all problems with your boombox step by step:

0. You must repair power switch.
Open boombox and make pictures of power switch.
When we see problem, we can give advice..
1. To resolve problem with tape decks - good cleaning, replacing belts...
2. When you listen radio or line in, VU meters work or not???
3. Maybe you must paint whole boombox...
4. After repair tape decks - you can play your old cassettes....
5. After complete repair, boombox must work very well and don't need modifications...

Don't worry about your english, I understand everything... :yes:
 

tatto

Member (SA)
Feb 11, 2015
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Thanks for
your reply! What about the 24/7 pressed play button? What can i do To fix it? Where may the problem be in the mech? I think that i have to contact an expert locally...

P.S. VU meter works whit radio and input, but only the right
 

tatto

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Feb 11, 2015
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Superduper said:
The reset to the mechanism is a mechanical function. Once the belt breaks the ability of the mechanism to reset is interrupted. You must therefore do this yourself manually by rotating the mechanism, usually the flywheel.
Oh god, it works! I've rotated the flywheel and the play/stop mechanism is working again. But the cassette dots are still not working. What about the left vu?
 

goodman

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2. About VU meter: Try to switch the wires - from left to right VU meter:
-- If then work left and right - not, then the indicator is OK,
and the problem is in the connections. Clean switch meter/light.
-- If then work right and the left - not, then the indicator is damaged
and need to change it. In eBay currently sells one: [ebay]321666511257[/ebay]

1. To resolve problem with tape decks - good cleaning, replacing belts...

0. You must repair power switch.
Open boombox and make pictures of power switch.
When we see problem, we can give advice..
 

tatto

Member (SA)
Feb 11, 2015
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Here are the pics. In the power switch case
I put a piece of kitchen paper so that it presses on the switch and it can hold the ON position without going down. Now look on the vu meters. The left one, has the red indicator 1mm behind the -20. The two meters are idle. Maybe it is stucked? How can i fix this?

IMG_20150213_143104.jpgIMG_20150213_142018.jpg
 

goodman

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Jun 14, 2011
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About VU meter:
Use solgerin iron and try to switch the wires - L to R and R to L to VU meter:
-- If then work left and right - not, then the indicator is OK,
and the problem is in the connections. Clean switch meter/light.
-- If then work right and the left - not, then the indicator is damaged
and need to change it.



To repair power switch - you must find similar to replace.
I hope and the other members to help you with advice.
 

tatto

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Feb 11, 2015
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To day i'll try vu meters crossing. If i have to replace it, i have to buy it on the net but the gf777H vu meters are light grey/black. The one you linked before is light blue wich is the gf777 one.
 

Cpl-Chronic

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May 14, 2012
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Try working the VU/light switch & clean it out good. maybe a bad contact there causing only 1 meter to connect. I had a VU not work on my first 777 until you pressed on the back of the plastic housing together & then the needle would start working again, presumably because the housing was separating & catching the needle on something. Try pressing on the back of the housing while it is energized & see if that works If so, you may need to re-glue the housing together with some structural epoxy.....

Cpl
 

tatto

Member (SA)
Feb 11, 2015
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Sorry, i was away for a lot and i didn't have time to check the vu meters. I've tried To change the position but the left vu meter is still not working. I think i have to buy a new one
 

goodman

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Jun 14, 2011
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Yes, you must replace VU meters.
On ebay have one for sale now. Don't miss this deal...
To repair power switch - you must find similar to replace.
I hope and the other members to help you with advice.
Good luck.
 

tatto

Member (SA)
Feb 11, 2015
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Thanks, i'll buy it soon! How much does the shipping in Italy cost?

Other questions guys: i've fixed most of the problems and i've cleaned all the knobs too, because they were all oxidated. Now the problem are the tape engines. Yesterday morning, i've checked the 2nd tape belt and it was outside the weel. I've fixed it and now when i press fast-fwd or rewind the engine is working (only in the 2nd tape). But when i put a tape inside the engine works very slow and it hangs sometimes. If i press Play nothing moves, and the white ground with the magnetic heads under the tape in the deck, does not come up to read and nothing moves. Should i throw the engine in the trash or is there something that i could to do to fix it? I'm not expert with tape engines they are too much complicated for a teenager like me who is born in 90'!
 

tatto

Member (SA)
Feb 11, 2015
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I'm studying the mech operations. In the first deck there was a black cable which was disconnected and now its working. The second deck is more complicated. If i press play, the motor doesn't start to rotate the flywheel. The first thing that everybody of you can think is that the motor is not working. But when i press rewind or fastfwd it works. If i press the play button nothing happens, and when i rotate the flywheel normally, the part under the tape, with the magnetic sensors is not coming up. On the first deck, if i press play and i rotate the wheel, the magnetic head is going up to touch the tape. On the second not. Seems that on the second tape the play button is not sending any signal to the motor to start to rotate, and there is a mechanical problem wich didn't leave come up the magnetic heads

EDIT 1:
On the second deck if i rotate the wheel ad usual with the pressed play button (simulating the rotating motor operation), nothing happens, the magnetic sensors are not coming up, and the mechanism to let the tape move are not working. Seems like a mechanical problem. I'll wait for your help

EDIT 2: deck 1 still not working.
Deck 2 after all the esperiments and repairments, starts nornally if i press play, the magnetic sensors come up but after nothing moves. And the play button keeps pressed if i press stop too. HELP

EDIT 3:
On deck two, seems a mechanical problem on the flywheel. Belts are okay, when i press play the mech starts but after one second it hangs and the stop mechanism doesn't work. I've opened it again, and i've tried to rotate the flywheel manually and at a certain point it hangs there. I've drawed a dot with a pencil on the wheel, and when its rotating at a certain point the black dot goes forward and then it come back. But when i opened the deck engines the mechanism manually worked...

EDIT 4:
Seems that engine power is too weak. When i press play, the belts are moving, the magnetic heads under the tape does come up, but at a certain point hangs because the last "tick" before the mechanism start, is too hard. I manually moved forward the flywheel to do the "tick" manually and the engine is working normally. If i press stop it resets normally too but when i press play it hangs again, and i have to help the engine manually.
 
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