5e3 eyelet board

[thor2015]

As the title suggests, I am building my first amp and decided on a 5e3. Since this is my first post, I'll give a little background.

First, I work for an electronics company. I started out in the programming/test department loading firmware on to certain boards and then testing them and then diagnosing/repairing the PCBs as needed. I did this for about 5 years and then decided to move over to manual assembly/wiring and most of my time is now spent laying out and building wiring harnesses and prototype projects.

I've been playing guitar sporadically for about 20 years. I have had 3 amps in that span of time. One was a solid state amp that was found by a friend on the side of the road with a smashed cabinet and damaged speaker but good electronics. I rebuilt the cabinet and put a 10" car speaker in it. The second amp was a Fender BP-15 that came free with a bass guitar my parents got me for Christmas, and the 3rd is a Line 6 Spider II amp that was given to me by another friend that was moving to Germany and didn't want to take it with him. I decided it was time to step up to a more decent amp.

I ordered a 5e3 kit from Tube Depot but decided to skip the PCB and go for an eyelet board from here. In addition to having more of a vintage/less mass produced look to it, I felt that component replacement would be easier with an eyelet board vs. a PCB.

On to the questions:

1. The Hoffman eyelet board has slightly different spacing than the original Fender fiberboard. I am guessing that this is so mounting holes can be drilled in the 4 corners for secure mounting. However, this slightly reduces the space on the power cap side where the original board had 3 separate wire pass-through holes drilled. From my research, Leo didn't put more work than was necessary into manufacturing to keep costs low. What purpose (if any) do these holes serve? Do I need them in the board or can I just route them underneath the board? I plan to use Teflon insulated wire as I love that stuff for soldering.

2. On the 5e3 board, how close to the edge do you guys drill the mounting holes? I want to make sure I don't interfere with the eyelets but I don't want to split the corners either. I do have a drill press so drilling straight and on point is not a problem. I just wanted to make sure.

[EL34]

You posted in the wrong area of the forum
You posted under my Hoffman amps boards section


I am moving this post to the main board

[thor2015]

Sorry. Thought since I was using your eyelet board specifically I would post asking questions regarding your specific board.

[sluckey]

There is plenty of room on the Hoffman 5E3 board to drill 4 mounting holes in the corners. I drill my mounting holes 1/4" in from each edge of the board. Don't look at the original layout when using Hoffman's board. It will just lead to confusion and unnecessary questions. The four mounting holes are the only holes you need to add to a Hoffman board. All connecting wires to the board can easily and neatly be attached to the top side of the board.

I prefer turret boards to eyelet boards.

[EL34]

Sorry. Thought since I was using your eyelet board specifically I would post asking questions regarding your specific board.

Sorry, this board here is where all tech questions go

[thor2015]

Thanks, sluckey- that helps out a lot. I like the turret boards too and even have a Hoffman turrett board for this amp but ultimately decided to go with the eyelet board. I sincerely appreciate the help.

EDIT: Sorry- was on the phone when I wrote this and just wanted to add. You mentioned Hoffman's board was different than the original. For the turret board this is true but his eyelet board is the same basic layout as the original Fender fiberboard just with a slightly different spacing. In the attached file, you can see the "original" fiberboard, Hoffman's eyelet board and his turret board with revised component layout.

[PRR]

> wire pass-through holes ....Leo didn't put more work than was necessary

Speculating:

Leo had board workers assembling boards a hundred at a time, flung into carts and shoved over to the chassis workers. This type of abuse tends to break flying wires. Bringing the wire through a hole to the lug makes it much more robust in factory chaos.

While modern production methods have changed a LOT, I'm sure you can recognize some production details used only to keep things intact as the stuff goes through the production process. One is snap-aways, where a remote sub-board is etched and jumper-wired as part of a main PCB. The support at both ends of the jumpers is more rugged than a jumper just flapping around in the trolley. At final assembly the sub-board is snapped-off and put where it goes (incidentally saving a solder-op at this point).

You don't have the production volume and pressure. You'll be gentle. I don't think you need the holes.

[thor2015]

Thanks, PRR for the input and that makes a lot of sense. We have boards like that at work, but they have little pieces that get snipped away after manufacturing/inspection. We have a PCB in particular that has a sacrificial daughterboard and both are run together through the line and then after the inspection process the nibs are snipped away allowing the boards to unplug from one another. So yes, I do see those kinds of things in manufacturing but not this method in particular when dealing with wires.

[sluckey]

You don't have to put a mounting screw hole in each corner. Look at this old '57 Harvard. Only two mounting screws and they are placed at just any convenient spot on the board. If you plan to use a thin board with a thin backer board I'd do it like the Harvard. All of the Fender eyelet boards were like this.

And you can certainly drill wire pass thru holes on your board. I would do that before mounting any components. Then you can chose to use them or not.

If this board is going to be mounted in a repro tweed chassis you will want to plan the placement of the board carefully. I suggest to temporarily mount all pots, jacks, and switches on the top and bottom sides of the chassis, then take the blank board and lay it inside the chassis. Mark the hole locations then drill. Dry fit to be sure everything will fit. You'll also probably need to mount the board and backer board directly to the chassis without using any standoffs. Otherwise the pots and jacks will be fighting the board for territory. None of this matters if you will use a bigger chassis.

Link to the Harvard pic...

     http://sluckeyamps.com/harvard/h03.jpg

[thor2015]

Got the holes in the board drilled. Here it is resting on the 1/4" nylon standoffs I have. From what I can see in the rest of the chassis, the input jacks are going to be the closest component to the board. I have them oriented this way so that the terminals that need to be jumpered are facing each other but I can rotate the bottom one if needed and just run a longer jumper wire. It's hard to tell from the photo, but I have right at 3/16" clearance between the board and the input jack.