Basic tube amp building tips? 5F1 Champ content...

[mrsage]

I know this is the DIY Stompboxes forum, but I know a couple of you all are amp builders/tweakers and I hoped you could either help me out or direct me to a "DIY Amps" kind of forum.

I recently started a Fender Champ 5F1 kit, and the e-mail tech support that was offered hasn't quite kept up with my building progress...

I have the board wired up and the proper wires attached to the sockets, but I'm not as familiar with amp parts as I now am with stompbox parts. That leaves me with some really basic questions that are probably assumed knowledge...

For instance, how do you wire up the Fuse Holder and the Pilot Light? They both have two places where you can attach wires, but the layout doesn't say which ones are which...and the pictures included in the instructions aren't very clear.

Here's the schematic/layout that was included:

http://www.kbapps.com/audio/schematics/tubeamps/fender/champ5f1.html
http://www.kbapps.com/audio/schematics/tubeamps/fender/champ5f1layout.html

Where do I attach the .047 capacitor? One end goes to ground, but what about the other end? It obviously attaches to the same place as the black wire from the power transformer...but which lug is that? The one at the end of the fuse holder or the one along the side?

Same question about the pilot light...there are two places to connect wires, but the layout only shows one connection. How do I wire that up?


So can anyone help me out? Is there a better forum for me to ask these questions?

I know I'll have a bunch of them, since there don't seem to be as many resources for amp building as there are for stompbox building...

[smashinator]

I can't help you with you questions, but I CAN direct you to www.ax84.com

[barret77]

ax84.com is really the best place around...
Ampage is also good.

[gorohon]

Definitely go to the AX84 forum for amps.  I just built a great sounding amp myself, a P1ex.  The fuse gets one of the lines from your 120VAC--It runs in series with one side of your house AC.  I know that the 5F1 has a weird short to ground standby, maybe you could get help from one of the AX84 regulars to come up with a better/ safer way of doing that.  The pilot light is hard to figure out on that layout.  I don't have the schem to refer to, but I'm guessing that it runs in series with some AC tap off of the PT secondary either the HV or the 5v or 6.3v tap.  What voltage is your pilot light?  What is the HV on your PT secondary?  I'm guessing that it is between 300-340V.
I'm by no means an expert on this stuff, so go to AX84.

[gorohon]

Okay,  your heater line (green on the layout) is in series,  so your pilot light gets the heater line for your power and preamp tube (hooks up to the light  before the tubes). It does not use the rectifier tube heater line.  It won't matter too much for both the fuse or the lamp which end recieves what.  I imagine that if the light can be hooked up wrong it just wont light.

[mrsage]

Hmm...

Thanks, I'll check them out. Their discussion forum could be a bit easier to navigate, but they seem to have some good info in there.

I found a picture that shows a fuse holder and a pilot light assembly similar to mine:

http://www.stf-electronics.com/delptran.jpg

I also updated my above post to include the schematic.

[gorohon]

Those black lines are your 120VAC.  One side goes to your fuse then from the fuse that  black wire will continue from the fuse to one side of your PT primary.  The cap will go from your outgoing fuse lug to ground.  Your other 120VAC line looks like it goes to that pot switch then to its side of the PT primary.  It wont make a difference wich side of the primary one of the 120VAC wires go to.  I hope you know where your PT primaries are at least.

[mrsage]

The PT primaries are going to be the black wires.

So it doesn't matter which order they go in, as long as I have AC 120V going into one lug and PT primary/.047 cap on the other one?

That makes sense.

[boogielicious]

Check out the Hoffman site as well.  Great bunch of guys who will help you.

http://p210.ezboard.com/bhoffmanamplifiers

Scott

[soggybag]

I think the 5.3V wires off the PT can go to either lug of the light. Imagine that the light is placed across the two wires. I would check the package the transformer came for the colors of the wires to make sure you are using the correct wires. Mine came with a diagram explaining what the voltages were for each wire, which were input, output and center tap.

I recently built a champ kit similar to this. This was not very hard to build and looks like it would be an easy platform mods. I have been thinking about adding a standby switch.

[Dan N]

It's frightening to think they would send you high voltage stuff and not really walk you through such basic important stuff.

Really look hard at the 12ax schematics. Use a 3 prong cable. Do not use the "death" cap.

The pilot is wired like the 6.3 heaters. Wire it like you wired the 6v6 and 12ax7. The same wire that goes to pin 2 of the 6v6 and pins 4 and 5 of the 12ax go to one of the pilot lugs. However the 6v6 pin 7 and 12ax pin 9 should be how the other pilot lug is wired. To ground on my champ.

Back to the 3 prong. It has a white, black, and green wire. Green to a good solid ground. The bolt of the PT is the usual choice. Wire the white to one of the PT blacks using a standoff. The black from the cord goes to the side lug of the fuse. Run a wire from the fuse end lug to the on/off switch. Connect the other PT black to the on/off swwitch so it connects to the wire from the fuse when switched on.

Hope this is clear and that you survive your amp.

Good luck!

[mrsage]

Thanks for the tips.

I hope I survive too!



Actually, I'm not too worried (only worried enough to stay safe ). There's a lot of information in the instructions and diagrams...I'm just trying to make sure I understand it before doing anything potentially dangerous. I won't apply any power until I know everything is connected safely. All that kind of thing is covered in the materials...just not which lug is which!

:lol:


By the way, I'm getting some good help over at the AX84 forums. Thanks for that suggestion! I think they can direct me from this point so I don't clutter the stompboxes forum!