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Post subject: How to date vintage Fender amp and circuit revision?
Posted: Thu Aug 15, 2013 6:05 pm
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As per title, I'm sure many of forum members would like to know what information is needed to accurately date a vintage Fender amp. There are knowledgeable people on this forum, but also the majority (like myself) are players without extensive knowledge in the field. (This is a call for the educated ones!!).

It is obvious that the chassis serial number is of a great help however there are other elements to determine/confirm the month/year of manufacture.

Looking at the codes on transformers is another way of confirming the originality (age) of an amp as well. I presume the pots are also dated. Where else in the amp should one look at to make sure all the parts are original and correspond with the chassis number?!

Stickers such the one below are not of a great help, especially if there are no stamps indicating month/year of production. (Besides, those stickers are widely available on ebay for cheap ...)

As for circuit, how is this to be determined? Again, stickers can be swapped, so how do we know if, say 1968 DLR drip edge has AB763 or AB868 circuit?

If we can get some photos to support the discussion that would be great.

Thanks for your help ... :)

[url][URL=http://s559.photobucket.com/user/draganc_photos/media/st1.jpg.html]Image[/url][/url]


Last edited by Nikola Tesla on Thu Aug 15, 2013 8:00 pm, edited 2 times in total.

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Post subject: Re: How to date vintage Fender amp and circuit?
Posted: Thu Aug 15, 2013 6:43 pm
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Nikola Tesla wrote:
(Besides, those stickers are widely available on ebay for cheap ...)


+1

Then there are nefarious villains (like myself) who print their own......

Image

:lol:

Most Fender amps built up through the 1969 model year will have a date ink-stamped within the chassis, adjacent the tag board containing the components for the bias supply or near the power transformer. Later editions lacking this ID info can be documented by noting the EIA codes on all of the amp's original components (pots, trannies, speakers, electrolytic caps) and creating a logical composite date from that data. This latter method is less accurate but is reliable enough to render a judgement within a four to six month period. Older cabinets themselves are also date-stamped, usually on the inside at the bottom or in the case of a speaker-only enclosure, on one of the interior cleats. Once a date is firmly established, the circuit revision can be reliably determined.

Arjay

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"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


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Post subject: Re: How to date vintage Fender amp and circuit?
Posted: Thu Aug 15, 2013 7:21 pm
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Regarding the ink stamp on the chassis, is the one from the photo how it should look like or does this number has a different meaning .. (4965 .. maybe 49th week of 1965?!?)


[url][URL=http://s559.photobucket.com/user/draganc_photos/media/pro.jpg.html]Image[/url][/url]


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Post subject: Re: How to date vintage Fender amp and circuit?
Posted: Thu Aug 15, 2013 7:34 pm
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Site to translate chassis numbers:

http://www.superiormusic.com/page195.htm

Sorry, if this is a repeat.


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Post subject: Re: How to date vintage Fender amp and circuit?
Posted: Thu Aug 15, 2013 7:40 pm
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Nikola Tesla wrote:
Regarding the ink stamp on the chassis, is the one from the photo how it should look like or does this number has a different meaning .. (4965 .. maybe 49th week of 1965?!?)


Your interpretation is 100% correct -- the 49th week of 1965.

Arjay

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"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


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Post subject: Re: How to date vintage Fender amp and circuit revision?
Posted: Fri Aug 16, 2013 12:53 am
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How can we ascertain a circuit model (revision), and what in particular a circuit is consisting of?


:?:


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Post subject: Re: How to date vintage Fender amp and circuit revision?
Posted: Fri Aug 16, 2013 1:17 am
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Once the build date has been determined (or approximated) go to a site like this......

http://web.archive.org/web/200807170341 ... fender.htm

Each of the blackface and some of the follow-on silverface circuit designations have a built-in date code which indicates when the revision was formally adopted and placed into production. In the case of the ubiquitous AB763, it was standardized in July of 1963 (the "7" and the "63" are the determining digits). Similarly, the Pro Reverb's initial nomenclature was AA165, ie: January of 1965. This latter revelation also proves beyond doubt that there were never any "pre-CBS" Pro Reverb amps, despite the insistence of many uninformed Ebay vendors. Further research into each schematic will reveal the differences between the various years of a particular amp model.

Arjay

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"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


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Post subject: Re: How to date vintage Fender amp and circuit revision?
Posted: Fri Aug 16, 2013 5:52 pm
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If AA165 is dated January 1965, and CBS took over in early 1965 (not able to ascertain the month exactly, but probably not January 1965), then some of the early pro reverbs may have been made under FEI ownership, providing the pro-reverbs were in production as early as January 1965?!?

Or maybe, the Pro-Reverb started its life only after CBS took over?!?

:o


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Post subject: Re: How to date vintage Fender amp and circuit revision?
Posted: Fri Aug 16, 2013 5:57 pm
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The sale of FEI to CBS was consummated on the 4th of January, 1965.

Likely no Pro Reverbs were shipped before then.

Arjay

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"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


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Post subject: Re: How to date vintage Fender amp and circuit revision?
Posted: Fri Aug 16, 2013 7:41 pm
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Probably the most interesting question for us who are not experts is - how to ascertain a circuit model.

Obviously the sticker wouldn't help, looking and understanding the schematics is out of question .. how to go about this? :?:


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Post subject: Re: How to date vintage Fender amp and circuit revision?
Posted: Fri Aug 16, 2013 9:40 pm
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LAYOUT. That's how I do it. Whip the chassis out and look at the specific resistors and caps. Compare them to the layout in question. The bias power supply, phase inverter section, and grid-to-ground resistors on the output tubes are some of the usual suspect areas to look at.

And for those who don't have dreams of resistor color bands & haven't had their gray matter dissolved from too many years of solder fumes.. this comes in handy:



http://www.amazon.com/Elenco-cc100-1-Co ... code+wheel

And this site:

http://www.aikenamps.com/ResistorColorCode.htm

Good hunting! :D


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Post subject: Re: How to date vintage Fender amp and circuit revision?
Posted: Thu Aug 22, 2013 3:00 pm
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It looks like an ordinary Joe guitarist has no chance in ascertaining circuit revision unless Joe becomes an expert.

:lol: :lol:


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