Last summer I was looking for a used Tweed Champ to use as my Man Cave amp. I wanted something to replace my Tech 21 TM-30 that was moving to my office at work. I found a few Fender Custom reissues on Reverb but decided to build my own Mojotone kit with a few audio quality and safety modifications on the original Fender 5F1 circuit.
I replaced the combination on/off switch/volume pot with a separate bat handle switch and 1M volume pot. This required me to relocate the fuse holder to the bottom panel. This mod moves the high voltage normally present in the combination switch/pot away from the signal chain reducing the likelihood of hum inductance through the volume pot. I also wired the fuse holder so that a blown fuse will break the hot side of the 120V and not the neutral as in the original wiring diagram. I upgraded some of the caps to beefier USA Atom Spragues instead of using the generic Mojotone components. The speaker output jack was changed to a standard 1/4" Switchcraft in place of the stock RCA so that I could drive an external cabinet. The stock ceramic speaker was OK, but I had a spare Weber 8A125H, so into the cabinet she went!
I took twice and maybe three times the amount of time that Mojotone estimates making sure that all my wiring was correct and neatly laid out. Everything checked out during the circuits tests and when I plugged in my Telecaster this little beast roared to life. Success! I'm in the process of designing a custom nameplate and then she'll be 100%. Photos were shot with my iPhone XR.
Super sweetheart amp. It feels awesome pulling off a project like that and especially when the result works and looks as great as yours. Passed the smoke test on the first try too. The only question is, can you resist the temptation to make a 5E3?
Tweed chassis, especially the 5F1, are rather cramped and difficult to work in. Just because the circuits are simple and they're physically small units, I think it's a mistake to regard them as being suitable for a beginner / 1st time build. The opposite really, because as size decreases, the awkwardness of getting the wiring tidily in place and nicely soldered increases significantly. So that said, you've done exactly the right thing and taken your time, with an excellent end result, well done!
And yes, seperating out the mains switch and the vol control is beneficial on all fronts.
FYI the fuse wasn't originally in the neutral line per se; rather the mains cord was ungrounded, 2 pin reversible, with the quasi 'grounding' 'death' cap hardwired to the fused side. For the amps that didn't have a ground switch to select which line gave the lowest noise when connected to the death cap, the user was expected to remove and flip the plug orientation if there was excess noise. Hence the death cap and fuse would naturall tend to end up on the 'hot' wire, the switch on the neutral. With modern mains wiring systems with grounded outlets, it is much better to put the both the fuse, then the switch, on the hot side, as you have done. One step even better would be to use a dual pole mains switch so that both sides get isolated when 'off', in order to accommodate outlets whose hot and neutral have been reverse wired (which unfortunately is all too common).
I hope you don't mind me mentioning, but a couple of things that have 'room for improvement' are the use of a wire nut for the neutral connection, and the insulation damage (soldering iron rash) to the hot wiring to the switch. The latter I'd put some heatshrink sleeving over at least, the former I suggest that you consider the use of a dual pole switch at some time in the future; wire nuts are horrid things, I'm surprised they're still seen as being suitable for use in mains wiring installations in some areas. Whatever, I don't think that an experienced builder would use them in a guitar amp, especially a combo, with all the vibration from being moved and the speaker.
It's regretable that kit suppliers are providing them / suggesting their use.
One thing I'd like to see is the chassis grounding method; unfortunately kit instructions and other non competent guidance all too often suggest the use of and eyelt on a power transformer mounting bolt; that's not compliant with good practice or international safety standards, which require the ground connection to use a dedicated fastener. Consider that the power transformer fasteners are the most mechanically stressed on the chassis, it's not good for one of those to also take on the only safety critical connection in the amp.
What appears to be a wire nut is actually where I twisted and soldered the neutral wires, then covered them with a crimped dead-end connector. The soldering iron rash is from the barrel nicking the insulation when I was heat-shrinking the fuse terminals. The DP switch is a good idea. I'll use a new piece of heat-shrink when I do the swap.
The chassis ground is achieved with a 3-lug terminal strip with a common 2nd lug. The strip is fastened to the chassis with a pop rivet on the rectifier socket and a bare conductor is soldered between all 3 lugs. I used pop rivets on the rectifier and power tube sockets.