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3 SHARP GF 777 with the same problem

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#1 wolff3012

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Posted 30 March 2014 - 04:12 PM

Hello

I have 3 of this big boomboxes but all have the same problem with the potis:

Mic fader- Tape fader- bass- treble works just on one channel.

I opened this boxes, but what i found in one box is a blown up capacitor on the potiboard.

10 Volts 100 µ... I measured 13 volts.

 

Pleas pleas help me... i dont know what to do... :sad:

I paid a lot of money to have *just one* fully working original 777, not 3 broken scrap boxes...

 

Thanks

Cookie



#2 Superduper

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Posted 30 March 2014 - 07:01 PM

Sorry to hear about your problems Cookie,  Well, 13 volts across a 10v rated cap will definitely blow it.  More concerning however is why you have 13 volts in that part of the circuit.  Obviously, that part of the circuit is probably rated for operation at far lower voltages, probably 3-6 volts or less.  I would definitely look at your power supply input voltage setting and make sure it's set for 220~240 volts, which is germany AC mains voltage, right?  If your boombox is set for or rated for ~120v (or less), then you've got a big problem on your hands since that cap is probably not the only thing fried.

 

Also, I'm afraid nobody can offer any kind of advice with so little details.  Your best bet is to take it in for repairs with a local electronics repair shop as I'm afraid your issues might be beyond the scope of your comfort level.



#3 BoomboxLover48

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Posted 30 March 2014 - 07:20 PM

mmm...........Strange!

 

Mine I checked and is working fine..

 

Norm already replied to this issue.



#4 baddboybill

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Posted 30 March 2014 - 07:46 PM

You never mentioned if left channel is same on all functions or certain functions? Plus how did you come up with your reading :hmmm:


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#5 wolff3012

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Posted 03 April 2014 - 04:35 AM

The power supply input voltage was settet on 220 volt. now its on 230- 240 Volt. We have in germany 230 volt.

The repairt shops wants for one hour ~40 €. It's too much.

I wish i could repair it...



#6 AE_Stereo

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Posted 03 April 2014 - 09:00 AM

When I received my GF-909, all its pots hardly made any contact. Both channels didn't work.

A rigorous treatment with Faderlube didn't work well first. So I gave a Deoxit shot followed by Faderlube made it working like new. 

 

Have you already cleaned all pots with Faderlube?



#7 wolff3012

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Posted 06 April 2014 - 11:19 AM

Its just one channel, the other channel works fine *bass- treble- Tape <-> mic fader. When i switch on *echo, the VU meter on the broken channel is lower... its not easy in english. I make a video...

 

Her is the Video

 

the brightness gets better in a few minutes...



#8 wolff3012

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Posted 28 April 2014 - 06:37 AM

Here are my 2 fully working 777 (Z- H)

 

And a little bicycle tour with my Sharp GF 9000



#9 Superduper

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Posted 28 April 2014 - 09:23 AM

I thought all 3 had the same problem, or did you fix 2 of them? :hmmm:



#10 wolff3012

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Posted 28 April 2014 - 03:37 PM

I have 2 working GF's, 2 not working GF's and 1 not working electronic part...

When i fixed them, i will let you know how...

But i'm happy, that i have an original GF 777 H *and* my first GF 777 Z with replaced speakers.

I have this GF five jears, he was on a lot of partys, in a lot towns from germany...

This GF 777 is (was) my first boombox... and I carried it many miles^^

 

(for translation error's, you have 2 years warranty with proof of purchase :-) )



#11 Superduper

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Posted 28 April 2014 - 04:10 PM

So you have (5) 777's?



#12 wolff3012

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Posted 29 April 2014 - 07:41 AM

I have 4 GF 777 and the mainboards from a 5'th

 

http://bilder.hifi-f...-777_422518.jpg

 

This is my 777 collection :-).

 

When i fix this stupid problem, i have 4 working GF 777...



#13 wolff3012

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Posted 09 May 2014 - 06:28 AM

The last two days i could mesaure resistors, transistors and capacitors in an electronik store. The men there helpes me a bit when he has time :-)

The same capacitor on the poti board blows up and near the *echo switch* an 470 µ 16 volt capcitor.

 

I soldered *all capacitors out and measured them...

 

and tested and tested and tested but new problems came out...

 

foto0587wsbrr.jpg

 

foto058842zot.jpg

This was the 10 V 100 µ cap...

 

But.... what do the *green* resistors ??? are this fuses, temperature-resistant... or touch resistors :blink:

foto0589soagi.jpg

 

The same resistor on the next day...

foto059173avg.jpg

HEEEEEEEELLLLLLPPPPPP  :sad: I just want to fix it !!!!... :-)

 

foto05908ilxn.jpg

 

foto05920zzg5.jpg

soldering iron holders are also hot ^^

 

put the 777 in die tonne and make the deckel zu :judge:



#14 Beosystem10

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Posted 09 May 2014 - 11:58 AM


I soldered *all capacitors out and measured them...

 

and tested and tested and tested but new problems came out...

 

 

:hmmm: I recommend that you take a look at This Page. :yes:



#15 wolff3012

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Posted 14 May 2014 - 06:39 AM

These 3 777 makes me grey hear, I came to the indecisive, to let it be^^

 

When the next radio *like a 777 arrived me, and all works perfectly, i have a lot parts for sale...

 

I hope it works, please pray for me :-)



#16 wolff3012

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Posted 25 August 2014 - 08:44 AM

And the nex GF 777 with that problem is here... WHY ???????
WWWWHHHHYYYYYY ?????... I have a lot parts, knobs, speakers, tapes and other parts, but NOT an idea to fix this stupid problem.

 

:bang: :bang:

: :

I could cry



#17 Superduper

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Posted 25 August 2014 - 12:16 PM

I have some questions.  (1) what do you mean the capacitors "blow up"?  Are you saying this literally?  Capacitors NEVER blow up unless you reverse the current or subject them to over voltage.  If you keep getting this issue, it may be because you are using 220/240 volts mains on a boombox set for 120v?  If not, then that sounds suspicious.  Capacitors do degrade over time and fail.  But usually, it is because the electrolytic solution inside dries up.  The cap can fail short circuit, open circuit, or the uF drifts out of range but you'll probably find ESR (equivalent series resistance) to be the cause of poor performance.

 

As for the lower than normal VU and volume on one channel, that is very common on Record/Playback switches that need cleaning.  Oxidation builds up between the contacts and makes for poor connection.  Did you clean that switch yet?  Do you know how or do you need instructions?  Try that first, you might be suprised.



#18 riker1068

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Posted 25 August 2014 - 12:46 PM

Do you know how or do you need instructions?  Try that first, you might be suprised.
 

I'd like to see the instructions on this. Just grabbed a 777 that will likely need a good deoxit sprayin :yes:  



#19 Beosystem10

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Posted 25 August 2014 - 02:33 PM

Do you know how or do you need instructions?  Try that first, you might be suprised.
 

I'd like to see the instructions on this......//.....

 

 

 

:hmmm: I recommend that you take a look at This Page. :yes:

 

 

Explained there.



#20 goodman

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Posted 29 August 2014 - 05:31 AM

As for the lower than normal VU and volume on one channel, that is very common on Record/Playback switches that need cleaning.  Oxidation builds up between the contacts and makes for poor connection.  Did you clean that switch yet?  Do you know how or do you need instructions?  Try that first, you might be suprised.

:agree: . I solve problems in my second SHARP GF 777 with very good cleaning and spraying.





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