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Post subject: Re: fender super reverb silver face hum problem
Posted: Sat Nov 08, 2014 6:02 am
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Front panel is esthetic , circuit number is the real thing . :D

CBS use Blackface circuit in many of Silverface amps until late 60 . These are very good amp like Blackface


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Post subject: Re: fender super reverb silver face hum problem
Posted: Sat Nov 08, 2014 6:15 am
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stratele52 wrote:
Front panel is esthetic , circuit number is the real thing . :D

CBS use Blackface circuit in many of Silverface amps until late 60 . These are very good amp like Blackface

Thank you for good news, :-)
Except tubes, filter caps and resistors and bias cap which parts must be change for better sounding?


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Post subject: Re: fender super reverb silver face hum problem
Posted: Sat Nov 08, 2014 6:28 am
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ali_k wrote:
stratele52 wrote:
Front panel is esthetic , circuit number is the real thing . :D

CBS use Blackface circuit in many of Silverface amps until late 60 . These are very good amp like Blackface

Thank you for good news, :-)
Except tubes, filter caps and resistors and bias cap which parts must be change for better sounding?


Yes for filter caps , and bais circuit filter cap
Wich resitors are you talking about ? Replace only if they are out of range .

Look at the the "big" 470 ohms on 6L6's.

Photos of inside your amp may help


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Post subject: Re: fender super reverb silver face hum problem
Posted: Sat Nov 08, 2014 7:01 am
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stratele52 wrote:
ali_k wrote:
stratele52 wrote:
Front panel is esthetic , circuit number is the real thing . :D

CBS use Blackface circuit in many of Silverface amps until late 60 . These are very good amp like Blackface

Thank you for good news, :-)
Except tubes, filter caps and resistors and bias cap which parts must be change for better sounding?


Yes for filter caps , and bais circuit filter cap
Wich resitors are you talking about ? Replace only if they are out of range .

Look at the the "big" 470 ohms on 6L6's.

Photos of inside your amp may help

http://s10.postimg.org/zd9pxuxjd/IMG_20 ... 205508.jpg
http://s29.postimg.org/7dr1866qv/IMG_20 ... 205603.jpg
http://s10.postimg.org/9u41yzqrt/IMG_20 ... 205619.jpg

Hope photos help you,,,
I mean resistors of filter cap must change or not?


Last edited by ali_k on Sat Nov 08, 2014 7:14 am, edited 1 time in total.

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Post subject: Re: fender super reverb silver face hum problem
Posted: Sat Nov 08, 2014 7:11 am
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And also
http://s9.postimg.org/uedhb0ljz/IMG_20141107_205736.jpg
http://s23.postimg.org/8bod9xhqj/IMG_20 ... 211338.jpg


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Post subject: Re: fender super reverb silver face hum problem
Posted: Sat Nov 08, 2014 7:45 am
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Thank's for pictures , too many are poor to help .

It could be a AB763 circuit but some kind of bad wiring dress and some cheap caps like CBS use
to cost cutting.

For a qualified tech who know Blackface amp or with electronic tube amp knowledge it could be easily mod to a real blackface .

Replace those whites capacitors ; these are cathode bypass capacitors. Use Sprague Atom 25 mfd / 25 volts or 50 volts , you need two Sprague Atoms for each white cap wich are double cap .

Bias filter caps must be 75 to 100 volts minimum and a 100 mfd or close is better than the original one


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Post subject: Re: fender super reverb silver face hum problem
Posted: Sun Nov 09, 2014 8:11 am
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Based on this picture:

http://postimg.org/image/7czgxmiu3/


Someone has used radial lead capacitors for replacement, and covered the second one down with rubber cement.
It appears the bottom capacitor is incorrect, and has a too low voltage rating, looks like someone may have put one of the 70uF caps in place of a 20uF 500V cap. :shock:

From the other pictures, and date code on the caps, I'd say this amp was made in 1969, maybe second quarter of the year, and is definitely an AB568 circuit based on the sandbox resistors and bias balance pot.

I'm guessing this is not what you want to hear, but you are over your head in attempting to repair this fine vintage amp yourself and should take it to a qualified amp tech before any more damage is done.

JMHO,

vinyl

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"Where confusion abounds, there's money to be made."


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Post subject: Re: fender super reverb silver face hum problem
Posted: Sun Nov 09, 2014 10:46 am
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I'd change ALL electrolytic caps. Note the polarity of the first two big ones. The ones that someone replaced with radial lead caps.

-----

Image


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Post subject: Re: fender super reverb silver face hum problem
Posted: Sun Nov 09, 2014 11:43 am
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hope this pictures help you to find out the right circuit,but please tell me which caps must change...already i can change and also solder by myself the caps and other things but if i find some expert tech i will give your instructions to my amp tech...so please,please,please tell your instructions in detail...thank you so much my friends

http://i58.tinypic.com/19p35j.jpg
http://i62.tinypic.com/dhbi3c.jpg
http://i61.tinypic.com/2i24ink.jpg


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Post subject: Re: fender super reverb silver face hum problem
Posted: Sun Nov 09, 2014 11:44 am
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rest of the pictures:
http://i62.tinypic.com/69l6js.jpg
http://i61.tinypic.com/11b6jkn.jpg
http://i59.tinypic.com/2gtceop.jpg


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Post subject: Re: fender super reverb silver face hum problem
Posted: Sun Nov 09, 2014 11:45 am
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and also:
http://i57.tinypic.com/2eqdk07.jpg
http://i59.tinypic.com/670191.jpg
http://i61.tinypic.com/dzynb7.jpg


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Post subject: Re: fender super reverb silver face hum problem
Posted: Sun Nov 09, 2014 1:23 pm
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dear friends after checking and correcting the polarity of the filter caps (combination of original old caps and two taiwanese cap) , thankfully the hum is GONE :-)
but still one problem remains, after turning down the volume knobs to zero ( in both channels) the amp is not mute and sound of guitar still heard from speakers...

other thing is , the sound is little bit harsh and it is not crystal clear and smooth sound.


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Post subject: Re: fender super reverb silver face hum problem
Posted: Sun Nov 09, 2014 1:26 pm
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It is not a AB763 circuit It is more a AB568 with those big 7 watts 150 ohms resistors at 6L6s

Wich caps to replace ? I tell you witch one yesterday and BMW too . Something not clear , need more information ?


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Post subject: Re: fender super reverb silver face hum problem
Posted: Sun Nov 09, 2014 1:28 pm
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ali_k wrote:
dear friends after checking and correcting the polarity of the filter caps (combination of original old caps and two taiwanese cap) , thankfully the hum is GONE :-)
but still one problem remains, after turning down the volume knobs to zero ( in both channels) the amp is not mute and sound of guitar still heard from speakers...

other thing is , the sound is little bit harsh and it is not crystal clear and smooth sound.



Please replace all these caps first , see my last post .


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Post subject: Re: fender super reverb silver face hum problem
Posted: Sun Nov 09, 2014 1:32 pm
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Lots of pub or "$@!& "( fishing ? ) where you put your photos, I don't trust this place .


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