1966 Deluxe Reverb Restoration

An Amplifier Restoration

I had the good fortune to find a 1966 Fender Deluxe Reverb on eBay.  It was the cabinet, the back panels, and the original Oxford 12K5-6 speaker in good condition.  The only thing missing was the chassis.  This is the story of building an accurate chassis and circuit for the 1966 Deluxe Reverb.  I reproduced all the circuit components to mimic what they looked like in 1966.   The quality of the reproduction capacitors was nearly identical to the 1966 capacitors that Fender used.

I start by ordering the chassis, transformers, and all the components and parts for the build.  I always start a restoration project like this by making the period-correct new capacitors;  in this case Astron Minimite electrolytics and blue tubular Paktron (actually Mallory) film capacitors.  Here they are getting ready to go onto the eyelet board (below).

The “insides” of the Astron Minimite electrolytics are new F&T or Sprague capacitors.  The blue tubulars are polypropylene;  either Solen or 150M.

(Above)  Here the resistors, capacitors, ceramic capacitors and the reverb bug are trial-fit on the board.  When all the components are in their assigned places, but not soldered yet, I flip the board over and solder all the back connections, including ground wires and the few wires that extend from the back of the board.  Then I solder all the components into place, and solder all the wiring (this is all waxed cotton push-back wire), to the eyelets.  (Below, in progress, but not complete yet).

At this point I put the chassis hardware together.  I age the transformers, cap can, tube covers, and the chassis itself, using my Secret Process that I intend to hand down to my grandchildren.

The filter caps (the π filter) are installed.  These are usually Astrons, but I have seen original Mallory capacitors here.  The resistors are all Allen-Bradley or better carbon composition.

 

The power transformers from this period had “C. S. A. TEST” printed on them.  The letters never seemed to be straight, for some reason, so I deliberately made them a little crooked.

Now I introduce the finished circuit board to the chassis.  There are two ways to do this – You can attach the board to the chassis and them solder in both ends of each wire, or, as I have done here, have the wires already on the board (a little long), and then just solder the loose end wherever it is supposed to go.  Do it my way.  Trust me.

 

A Note on Twisting Wires:

Any wires that carry AC current, and those DC-carrying wires that are susceptible to nearby AC fields, should be twisted together.  And there is a correct way to twist wires –  (a lot of people get it wrong).  In order for the twisted wires to function in common mode rejection, they must be twisted tightly, and there must not be any space between the twisted wires.  In the above photo, the power transformer wires (VAC) have multiple turns per inch of length, and they are tightly twisted – no gaps.  Do this correctly and your amp will be quieter and well-behaved.

 

The last wiring step is the filament wiring.  Trying to do it earlier, or God forbid, first, will be a lesson in frustration and aggravation.  Again, trust me.  In the above photo, I am almost done, and ready to start measuring and cutting green wire.

 

 

(Above).  Finished with filament wiring.  I use 18 AWG for the output tubes, and then 22 AWG for all the preamp tubes.  Do a good job here of twisting the wires (I use a drill motor), and keep track of the polarity of the wires – in other words, one wire should go to the top connection of all the tubes, and the other wire should go to the bottom connection.  It’s a whole lot easier if your wires are two different colors, but Fender used all green wire, so that’s what I did here, since I am doing a restoration.  The filament wires should be an inch or more up in the air, aligned in a straight line horizontally, and drop down onto the tube socket connections.  Do not loop the filament wire around the socket, or have the filament buss at all different angles.  All of the above serves to reduce hum in the amp.

I couldn’t find a commercial Deluxe Reverb brass grounding plate, so I made one out of cartridge brass.  The brass grounding plate is where all the circuit grounds land, and the plate itself is soldered to the chassis.  Do not try to solder the plate to the chassis with a “regular” soldering iron.  It will never work, although it might look like it worked.  You need a very large mass iron with several hundred watts of power.  They are available on eBay, Amazon, and the like.

I had quite a time finding a functional tin diode of the time period, but I eventually landed 10 of them, NOS.  You can see it on the little bias board, above, behind the brown Astron bias capacitor.  The other impossible to find part was the “courtesy outlet”, which in the day was a “2-prong” receptacle.  I finally found an original one; paid $45 for it (sigh).

Here is the completed chassis.  It looks like it just came out of Fullerton in 1966.

The original tube chart.

The finished product.  The customer was very happy.  The amp sounded absolutely perfect.  Very chimey and balanced, and tone to die for.

…and the back side.  Note the Fender “F” cover on the speaker jack.  The only thing not as original is the three-conductor power cord, and of course there is no “Death Cap”.