3 SHARP GF 777 with the same problem

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wolff3012

wolff3012

Member (SA)
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
 
Superduper

Superduper

Moderator
Staff member
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.
 
baddboybill

baddboybill

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


Sent from my iPad using Tapatalk
 
wolff3012

wolff3012

Member (SA)
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...
 
AE_Stereo

AE_Stereo

Member (SA)
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?
 
wolff3012

wolff3012

Member (SA)
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
http://youtu.be/3xpjU-7X0h4

the brightness gets better in a few minutes...
 
wolff3012

wolff3012

Member (SA)
Here are my 2 fully working 777 (Z- H)
http://youtu.be/VRoLOaQi01Q

And a little bicycle tour with my Sharp GF 9000
http://youtu.be/2FKNbGpSBEs
 
wolff3012

wolff3012

Member (SA)
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 :-) )
 
wolff3012

wolff3012

Member (SA)
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...






This was the 10 V 100 µ cap...

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



The same resistor on the next day...
[url=http://abload.de/image.php?img=foto059173avg.jpg]

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


[/url]

soldering iron holders are also hot ^^

put the 777 in die tonne and make the deckel zu :judge:
 
wolff3012

wolff3012

Member (SA)
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 :-)
 
wolff3012

wolff3012

Member (SA)
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
 
Superduper

Superduper

Moderator
Staff member
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.
 
riker1068

riker1068

Member (SA)
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:
 
goodman

goodman

Member (SA)
Superduper said:
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.
Click to expand...
:agree: . I solve problems in my second SHARP GF 777 with very good cleaning and spraying.
 
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