Please take a look at my 5F1 layout

[fabiomayo]

It's my first build and I think I'm about ready to solder.
It's a 5F1 with a tone control (defeatable) a la 5F2-A.
How's the "predicted" lead dress? It's a mix of Fender
layout and Angela's. Plus some of my uneducated
mess around...

What about the grounding? Is it okay?

Sorry for the messy layout. Almost everything is scaled.
The chassis can be a bit longer. I'll cut it tomorrow.

If anyone could take the time, it's greatly appreciated.

Thank you so much.

[Tom Phillips]

Fabiomayo,
I'll contribute a few power supply related ideas. Otheres will probably have more.
1) Use a two wire (twisted pair) 6.3V heater supply with a virtual center tap ground made with two 100 Ohm resistors to the chassis. This includes the pilot light circuit. Fender originally used the chassis as one conductor as a labor saving measure. Not because it was better.
2) Use the AC mains wiring that you see on modern schematics with the switch and the fuse both in the "Hot" lead. If I find a diagram, I'll post it.
3) No need for the .047uF "death cap" that you have from the fuse holder to the chassis since you are installing a grounded power cord.

Tom

[fabiomayo]

Thanks for your quick reply, Tom.

1) Ok. Let's see if I got this straight... So I use the wire shown on the
layout I made and twist it with another one, connected only to ground
through a 100R resistor on each end, is that remotely right?
2) No problem. From the AC plug to the switch and series to the fuse,
then to the power tranny. The other wire goes direct from AC to PT.
3) NO idea what's that cap for. I'll lose it...

Thanks a lot. Any other thoughts?

[MWJB]

Ground your main & screen filters to a PT bolt, ground your preamp filter, pots and preamp circuit grounds to the input jack. Don't link up all the grounds on the board/buss, run seperate wires from each grounded eyelet to its ground terminal.

Personally, I'd up the capacitance at the main filters, 40 to 100uf.

Yes, you have the idea re the heaters. Ground the 100ohms to a PT bolt.

[fabiomayo]

Thank you for your reply.

1) To ground the preamp circuit to the input jack should I solder each wire
to the first lug or should I install a ground terminal along with the jack?

2) I've seen schems with an added 16uF or every electrolytic 16uF.
What are the benefits? Lower hum?

3) Ok on the PT bolts.


Thank you so much.

[MWJB]

Sure, solder each wire to the first lug. The pot grounds (vol LH tab & tone pot .005 cap) can be soldered to the back of the pots (remove varnish from the pot body), then a single busswire can run from the pot bodies to the input jack. The circuit board ground wires can then run to the point where the buss wire meets the jack ground lug.

More filtering at the first stage will reduce hum.

[fabiomayo]

wow. That was quick. Thank you so much.

I'll do the grounding scheme as you said. I'll also elongate the board
to acomodate one more 16uF. As you may noticed there's enough
room for replacing the 8uF with 16's and I'll try that once I get things
up and running. Thank you so much.

Any more ideas? The crossing and parallels wires are okay? (I'm really
a noobie here....)

Thanks!

[MWJB]

There are various schools of thought, but maybe keep the 8uFs at the screens & preamp, the 32uF (or larger) main filter will take care of the hum.

You don't really want the plate & grid wires running parallel and too close to eack other, I use shielded cable for grid wires as a matter of course (mount the 68Ks on the input jack rather than on the board). Keep grid wires away from the heater wires as much as possible.

[fabiomayo]

Thanks again, MWJB.

Here's the updated layout. I'll move all components on the board to the right
to occupy the space where the 68k were and to provide space for another
16uF on the leff-hand side of the board. I'll be making the board myself so it
could be as big as needed. I'll probably also move the 12AX7 socket just to
keep the lead dress similar to what it is. There'll be one terminal to each wire
on the PT bolt ground.

I think the heater wires are far enough from the grid wires, right?

Thanks a lot. I really appreciate your generous advice.

[fabiomayo]

Also this is the circuit:



Resistors are 1 watt carbon film, caps are Mallory 150s, electrolytics are
Sprague. Plate resistor are metal film Vishay 1/2 watt and power supply
resistors are 3w metal oxide. Maybe this is all over the top, I don't know...

One more question. Should I use the metal oxide on the negative feedback
or would the carbon film do fine there? Can I mess with res values here?
If so, what to expect?

Thanks!

[teletroy]

Thanks again, MWJB.

Here's the updated layout. I'll move all components on the board to the right
to occupy the space where the 68k were and to provide space for another
16uF on the leff-hand side of the board. I'll be making the board myself so it
could be as big as needed. I'll probably also move the 12AX7 socket just to
keep the lead dress similar to what it is. There'll be one terminal to each wire
on the PT bolt ground.

I think the heater wires are far enough from the grid wires, right?

Thanks a lot. I really appreciate your generous advice.

Your heater wires aren't going to work like that. You need to unground pin9 on your preamp tube, and on your pilot light and attach the other green wire to them. You'll need to connect pin 4 and 5 together on the same green wire. You'll also need to attach it to pin 2 on your power tube.

https://taweber.powweb.com/store/5f1_layout.jpg <take a look, it might help you figure it out.

Basically you have two green wires- 1 wire goes to both sides of the pilot light - then 1 will go to pin 7 on your power tube and pin 9 on your preamp tube. The other wire will go to pin 2 on your power tube and then 4 and 5 on your preamp tube. Somewhere in the chain you need the 100ohm resistors going to ground -- one attached to each green wire. If you had them both going to the pins as you have it drawn up now, you'll melt, and you dont want that. good luck

[fabiomayo]

Thanks, teletroy.

I got really confused with the heater wring. Thank god for places like this and
everybody here! Here's the corrections. Did I do it right? Can I ground through
the 100R as drawn? Should I run a wire to the PT bolt ground?

Also, I shoudn't ground pin 1 of the 6V6, right?

On the Weber layout, the fuse comes first (from the AC outlet) and then to
the on/off switch. I did the opposite way. What's best?

Thank you all so much. I guess with guys like you all helping out I'd be hard
pressed to burn down the house....

Thanks

[fabiomayo]

Oh.. And one more question... The grounds on the jacks (both input and
speaker) is to be trusted? Or should I run a wire from them to the star ground
at the PT bolt?

Also, I read somewhere about using an insulation board underneth the circuit
board. Lifting it won't be enough?

Thanks.

[nico.verduin]

If you lift the board then an insulation beneath is not required. I would lift the board at least 7-8 mm.
Nico

[djl audio]

What software are you using?

What software are using to do your layout? Where did you get it? Thanks