It is currently Mon Mar 16, 2020 10:51 am

All times are UTC - 7 hours



Post new topic Reply to topic  [ 59 posts ]  Go to page Previous  1, 2, 3, 4
Go to page Previous  1, 2, 3, 4
Author Message
Post subject:
Posted: Wed Nov 10, 2010 9:26 pm
Offline
Professional Musician
Professional Musician

Joined: Fri Jun 26, 2009 6:53 pm
Posts: 2252
Location: Harvard IL
Hi Chris, and nice buy. My guess about the brown gunk, would be that a 'lytic cap took a dump. Especially, if it's on the board too. As for the circuit, a simple way is to get the layouts for the: AB763, AB568, AA1069. AA1070. Start at the bias pot and follow that to the circuit board. If it leads to an apex of two 220Kohm resistors it's the AB763. If not, compare the other layouts at the power tube sockets. Here's some info on the 3-prong job. http://www.unclespot.com/3prongconversion.JPG Good Luck ! Art

_________________
None of Us are free, if One of Us is chained !


Top
Profile
Fender Play Winter Sale 2020
Post subject: Re: Grounding question
Posted: Wed Nov 10, 2010 10:20 pm
Offline
Rock Icon
Rock Icon
User avatar

Joined: Wed Mar 31, 2010 12:48 am
Posts: 26416
Location: Tombstone Territory
taskerc wrote:
I did the check you mentioned already and found it to be 1967 but form this I was not able to better understand if I "really" have an AB763, as listed on the tube position paper or if it was one of the other variants listed there. In my forum trawls it appears that the relationship between circuit type written on tube sheet can differ from reality.

But I guess more importantly , should I really care which circuit variant I have?

I may post a picture tomorrow - if the brown gunk is really nicotine, this amp has some SERIOUS stories to tell :-) It truly is gunked up.

I am quite jazzed about this project now and I probably should not mention I found this in a Garage sale and offered $50 and it was accepted. And moreso, I plugged it in (even though I probably should have been more careful) and it worked, well mostly. Hum, and some functions not right but it made music, and quite nicely at that given that the 'lytics Caps are all candidates for replacement. In the strip down I found the handle screw retainer thingy wedged into the works near the power supply section. I am lucky that powering it up did not blow it up. It has all the original blue molded caps still and looks like it has not been modified as of yet.

But it is a silverface with black speaker cloth and no edge trim on speaker baffle. Being a Canadian variation it has "Radio Speakers of Canada" 10"ers in it. So I am not sure exactly what it is in reality. Front panel has black lines (why is this important? I have seen it mentioned a good few times).

Thanks again!

Regards, Chris


The speakers are undoubtedly replacements. The OEM speaker for a Super Reverb of this era was generally the alnico CTS -- I owned a '67 SR like this (bought new -- it was my first new Fender amp) and that's what it was equipped with. The blackline front panel was only used in '67 and '68, along with the blackface-era "snowman" knobs (the "8" is shaped like a traditional snowman and the set-screw is an allen type). From what you describe the amp is probably the AB763 circuit revision which would be superceded by the AB568 in the early summer of 1968. For a comparative look at circuits, go here......

http://www.ampwares.com/amp.asp?id=98

Additional dating info can be found by examining the EIA codes stamped on the housings of all four trannies on the chassis and embossed on the control panel pots. Congrats on a great find and enjoy.

HTH

Arjay

_________________
"Here's why reliability is job one: A great sounding amp that breaks down goes from being a favorite piece of gear to a useless piece of crap in less time than it takes to read this sentence." -- BRUCE ZINKY


Top
Profile
Post subject:
Posted: Thu Nov 11, 2010 12:50 am
Offline
Professional Musician
Professional Musician

Joined: Fri Jun 26, 2009 6:53 pm
Posts: 2252
Location: Harvard IL
Arjay, I'm inclined to think Chris has the real deal, an AB763. Weren't the faceplates with the black lines the earliest iteration ? And Chris, those blue molded Mallory caps can last forever, and are top-shelf caps. So unless they are way out of spec or are leaking a lot of DC, keep those guys ! Art

_________________
None of Us are free, if One of Us is chained !


Top
Profile
Post subject:
Posted: Thu Nov 11, 2010 1:11 am
Offline
Rock Icon
Rock Icon
User avatar

Joined: Wed Mar 31, 2010 12:48 am
Posts: 26416
Location: Tombstone Territory
aclempoppi wrote:
Arjay, I'm inclined to think Chris has the real deal, an AB763. Weren't the faceplates with the black lines the earliest iteration ? And Chris, those blue molded Mallory caps can last forever, and are top-shelf caps. So unless they are way out of spec or are leaking a lot of DC, keep those guys ! Art


I agree, Art. All indications are, it's an AB763. The black-line face plates were discontinued with the end of the '68 model year (though I've seen a rare example or two on some '69 models). A tragedy that the original baffle with the drip-edge grill has disappeared but if the gentleman is handy with tools and knows where to find the missing parts he'll end up with one fine amp. I may be starting a drip-edge silverface restoration very shortly myself.

Arjay

_________________
"Here's why reliability is job one: A great sounding amp that breaks down goes from being a favorite piece of gear to a useless piece of crap in less time than it takes to read this sentence." -- BRUCE ZINKY


Top
Profile
Post subject:
Posted: Thu Nov 11, 2010 5:50 pm
Offline
Hobbyist
Hobbyist

Joined: Wed Nov 10, 2010 2:23 pm
Posts: 78
Thanks Arjay and Art.

Well the bias pot goes into the apex of 2 resistors that look like Red Red Yellow so I think they are 220K. So that is good. Also power transformer has 68 in number as does the tiny one between 12AX7s, but others have 67.

Also speakers are staggered so I wonder if the head was put into another cabinet. The front baffle is screwed on. Also has set screw knobs with snowman 8's. The rectifier tube is a 5u4.

The gunk is everywhere on the underside of the chassis, but strangely not as apparent on any components.

So I think the first plan is to get some Spragues for the large electrolytics in the doghouse and to get that two prong converted to safer three prong. Anything else I should tackle early.

Any recommendations on cleaner for the pots - Craig Deoxit is always mentioned.

I am pretty jazzed now - this is going to be a very fun project now that I have more info on the patient.

I will take some before photos as a record and post some - she is not in great condition now, but she will be ;-)

Chris


Top
Profile
Post subject:
Posted: Thu Nov 11, 2010 6:08 pm
Offline
Rock Icon
Rock Icon
User avatar

Joined: Wed Mar 31, 2010 12:48 am
Posts: 26416
Location: Tombstone Territory
Get some pics up for us, Chris.

We can offer a more comprehensive assessment if we have some visual cues to look at. Or you can e-mail them direct to me......

<phantoms4ever(at)cox(dot)net>

The staggered speaker array gives me pause -- I'd like to see it. You may be right though......an older chassis in a newer cab. The standard rectifier for an AB763 is a GZ34/5AR4. If the tube chart inside calls for a 5U4 then the cab is a later example -- possibly as late as 1970, since that was the final year for the screw-in baffle. IIRC, the 1970 model did employ the staggered speakers and a 5U4 rectifier.

HTH

Arjay

_________________
"Here's why reliability is job one: A great sounding amp that breaks down goes from being a favorite piece of gear to a useless piece of crap in less time than it takes to read this sentence." -- BRUCE ZINKY


Top
Profile
Post subject:
Posted: Thu Nov 11, 2010 7:18 pm
Offline
Hobbyist
Hobbyist

Joined: Wed Nov 10, 2010 2:23 pm
Posts: 78
Started a new topic to stop thread jacking the other topic:
http://www.fender.com/community/forums/ ... 085#557085


Top
Profile
Post subject:
Posted: Fri Nov 12, 2010 6:26 pm
Offline
Hobbyist
Hobbyist

Joined: Sat Nov 06, 2010 3:14 pm
Posts: 2
I have a silverface vibro champ from the 70s. Sounds great! Stock speaker and everything. I believe the silverface champ has the same circuit as the blackface ones. It's the amp I use the most at home because I can crank it and not blow my neighbors away. You can get a good silverface champ for a decent price still.


Top
Profile
Post subject:
Posted: Sat Nov 13, 2010 1:11 am
Offline
Rock Icon
Rock Icon
User avatar

Joined: Wed Mar 31, 2010 12:48 am
Posts: 26416
Location: Tombstone Territory
Kirkland wrote:
I have a silverface vibro champ from the 70s. Sounds great! Stock speaker and everything. I believe the silverface champ has the same circuit as the blackface ones. It's the amp I use the most at home because I can crank it and not blow my neighbors away. You can get a good silverface champ for a decent price still.


+1

If you haven't already done so, try connecting your Vibro Champ to a 2 x 12 or 4 x 12 cab (4-ohm impedance only). You'll be pleasantly amazed at how nice a 6-watt amp can sound.

(needless to say, it will be substantially louder than a single ceramic Oxford 8")

:mrgreen:

Arjay

_________________
"Here's why reliability is job one: A great sounding amp that breaks down goes from being a favorite piece of gear to a useless piece of crap in less time than it takes to read this sentence." -- BRUCE ZINKY


Top
Profile
Post subject: Re: Silverface
Posted: Wed Nov 30, 2016 7:01 pm
Offline
Hobbyist
Hobbyist

Joined: Wed Nov 30, 2016 6:49 pm
Posts: 1
Location: Boucherville
I have a Bronco amp. I want to know witch one is the first. The logo of my amp doesn't have "amp" under Bronco. Its all the same amp but there ´s no amp ?????
Thx philibert


Top
Profile
Post subject: Re: Silverface
Posted: Wed Dec 07, 2016 7:30 am
Offline
Rock Star
Rock Star
User avatar

Joined: Sat Jul 03, 2010 2:18 pm
Posts: 6544
Philibert wrote:
I have a Bronco amp. I want to know witch one is the first. The logo of my amp doesn't have "amp" under Bronco. Its all the same amp but there ´s no amp ?????
Thx philibert


I have a 1967 Bronco. It has the "BRONCO -AMP" logo. You have photo of yours?

Image


Top
Profile
Post subject: Re: Silverface
Posted: Wed Dec 07, 2016 7:47 am
Offline
Rock Icon
Rock Icon
User avatar

Joined: Wed Mar 31, 2010 12:48 am
Posts: 26416
Location: Tombstone Territory
A fine specimen indeed, Steve -- it looks exactly like mine. Really early examples may be seen with the AA764 tube chart as used on the Vibro Champ and some '68 editions wore the tailless Fender logo on the baffle board.

Arjay

_________________
"Here's why reliability is job one: A great sounding amp that breaks down goes from being a favorite piece of gear to a useless piece of crap in less time than it takes to read this sentence." -- BRUCE ZINKY


Top
Profile
Post subject: Re: Silverface
Posted: Wed Dec 07, 2016 8:34 am
Offline
Rock Star
Rock Star
User avatar

Joined: Sat Jul 03, 2010 2:18 pm
Posts: 6544
Arjay, thanks!

I have BRONCO tube sticker. AA764.


Top
Profile
Post subject: Re: Silverface
Posted: Wed Dec 07, 2016 2:17 pm
Offline
Rock Icon
Rock Icon
User avatar

Joined: Wed Mar 31, 2010 12:48 am
Posts: 26416
Location: Tombstone Territory
Same here. Only a handful of Bronco's got the Vibro Champ tube chart, and only because Fender's graphics department didn't have them ready for the amp's debut in the summer of '67.

Arjay

_________________
"Here's why reliability is job one: A great sounding amp that breaks down goes from being a favorite piece of gear to a useless piece of crap in less time than it takes to read this sentence." -- BRUCE ZINKY


Top
Profile
Display posts from previous:  Sort by  
Post new topic Reply to topic  [ 59 posts ]  Go to page Previous  1, 2, 3, 4
Go to page Previous  1, 2, 3, 4

All times are UTC - 7 hours

Fender Play Winter Sale 2020

Who is online

Users browsing this forum: No registered users and 2 guests


You cannot post new topics in this forum
You cannot reply to topics in this forum
You cannot edit your posts in this forum
You cannot delete your posts in this forum

Search for:
Jump to: