FWIW - I typically tackle the build in stages and for now I will avoid getting too far into the details but try to define the stages.
But First - An Important Notice you must read before you start a DIY guitar amp - Tube type guitar amps create lethal voltages that can potentially kill you. If you don't know what you are doing and take the necessary precautions, you are at risk of giving yourself an unpleasant if not lethal electrical shock.
1) Step 1 - Gather up all the parts and do an inventory. Verify that you have a correct schematic and a layout to work from.
2) Step 2 - Make certain you have all the tools you'll need including a good soldering iron, a digital multi-meter, a good set of small wire cutters and also a set of needle nose pliers.
3) Step 3 - I start with the chassis prep work - this includes adding any extra holes to punch, drill or thread. After that I clean the chassis with warm water and dish washing soap - this works really nice for aluminum chassis'. I have always thought it would be great to be able to run them through the dish washer but my wife has no sense of humor about that idea. Once the chassis is clean you can do any painting, powder coating, or anodizing. If you want any labeling done by laser etch or silk screen, this is the final step in chassis preparation.
4) Step 4 - This begins the fun. Mount these items in the following order:
a) Any internal standoffs, ground tabs, terminal strips, or other items that mount directly below the transformers or circuit boards.
b) Transformers
c) IEC socket
d) Fuse holder
e) Impedance switch
f) speaker jacks
g) Faceplate
h) Pilot light
i) input jack
j) On/Off and Standby switches
k) potentiometers
l) terminal strips and ground tabs
m) surface mount components (chassis resistors etc.)
5) Step 5 - Wire the Power transformer beginning with running the safety ground wire from the IEC socket to a ground point on the chassis - this is the only wire that uses these two terminals. Do not use this ground point for a signal ground connection. Then continue wiring the AC socket, on/off switch, pilot light. In a traditional TrainWreck amp the neutral wire is also switched.This is not considered a "best practice" in modern electronics, but is typical in a traditional Wreck build. Once the AC wiring is finished, tie all center taps to ground as appropriate, and heater wires to either a terminal strip or the first tube they feed, whichever is appropriate.
6) Step 6 - Wire the secondary of the output transformer to the impedance switch and any other connections that can be made before the power supply is created. Don't connect the B+ wire or any other wires to the primary side of the OT yet.
7) Step 7 - Wires the tube heaters. This is usually one of my least favorite tasks, especially on a Liverpool or Rocket (AC30) type of build because they have so many tubes in them. I prefer to use two colors of #18 stranded wire for the tubes. I twist the wires together by taking about 24" of each wire and clamping on end of the pair in a vice, then the other end I put into my electric drill... you can figure out what to do next... you'll never be tempted to use a loose sloppy twisted pair if you do this. From the length of twisted pair I cut the correct length to go from one tube to the next, always using the same color wire on the same pin for each heater in any given type of tube.
Step 8 - At this point I suggest some electrical testing. (Edit July 1, 2017 -- This is the step where a light bulb limiter can be very useful especially if you are a novice builder). Make sure you put a fuse into the fuse holder. Do a visual inspection and make sure every hot wire is connected to a safe and proper place and/or is properly insulated or isolated to avoid an electrical shock or short. The most important wires to verify are the high voltage taps from the power transformer secondary... make sure again that they are completely insulated and isolated from touching each other, the chassis, and you. If you have properly wired things up to this point, the light should come on and power transformer will create the appropriate voltages. Using an isolated connection you can measure the high voltage coming across the secondary B+ taps. You can also measure the heater voltages across the heater taps, and then to each individual socket. If all this goes well, verify that everything is again insulated and isolated and you can put a tube into each socket and verify that the the heaters light up... this often gives me a great feeling of accomplishment.9) Step 9 - I will trivialize this for now by saying "wire up the power supply". This will require more information and detail later. After it is wired up, make lots of measurements and recognize that at this point you have energized the filter capacitors and they are carrying potentially lethal voltages. After you unplug the amp from the AC mains power, you will need to bleed those filter caps to ground before sticking your fingers into the amp to do any further work.
10) Step 10 - Install the preamp board. Some folks prefer to mount the components before they put the board in, others do it with the board in place. I've done it both ways but which ever way you choose, make sure you have all the wires and connections complete on the back side of the circuit board before you mount it in there. Typically this involves hooking up the B+ connections and grounds to their appropriate locations.
11) Step 11 - Install and wire the components to the power tube section, including the connections back to the preamp board. Again, I have trivialized this and details will need to be filled in as appropriate for your build.
12) Step 12 - Wire the phase inverter between the tube and the preamp board. This is again just doing things in a given order and your specific build will determine what is actually mounted and wired up.
13) Step 13 - Wire the gain stages in descending order, between the tube sockets and the preamp board.
14) Step 14 - Wire the input jack. I always use shorted input jacks that switch open after as a plug is inserted. This makes for a minimum noise level as the amp sits there at idle... just verify that the switch indeed un-grounds itself as you insert the plug.
15) Step 15 - Wire the volume control and tone stack.
16) Step 16 - Verify that everything matches the layout and agrees with the schematic.
17) Step 17 - Power up the unit... if you feel the need and want to be cautious, you can use a light bulb limiter or other forms of circuit protection. In modern amps with modern components, the filter caps do not need to be "formed". This only is needed with very old caps and I don't suggest you use them.
18) Step 18 - Put in the tubes and hook up a speaker or some sort of load on the output. Tube amps do not like open circuits on the output section and it can ruin your output transformer if you don't attach a speaker cabinet. I also use an auto shorting jack for the speaker output so that if you forget to hook up a speaker, the amp is shorted to ground - this protects the output tranny and you'll figure out something is wrong by the silence of things.
19) Step 19 - If all is well, then your amp should sound great... if not then it is time to read the trouble shooting guide (which has not been written yet).
Edit - July 1, 2017 -- YMMV - For myself I don't always adhere to this protocol in perfection, but I do find that it does make for a good flow of the project and helps me avoid getting things out of order and having to undo/redo something. Seems that no matter how careful I am, doing it right the first time always looks better than my best unsoldering and repair efforts.
