What holds the eyelet board in a 5e3?

[mbratch]

Sorry - noob question:

I am just getting started on my first 5e3 kit. I'm used to poking around inside BF amps that have the eyelet board fastened to the chassis with a couple of sheet metal screws. But this board doesn't have any mounting holes, nor does the chassis. I noticed looking at pics of the insides of various 5e3's that there aren't mounting screws (that I could see anyway).

So, I can see how the wiring might hold the eyelet board in perhaps, but what about the insulating board underneath? What holds that in place if that's how it works?

Thanks!

[Resonator Guy]

Here is one I can answer since I asked the same question a while ago. Follow this thread. There are some good explanations and pictures. I used two sheet metal screws with PVC spacers from cleaning bigger wires between the boards and it seems to have worked perfectly. There are pics of where to drill your holes and all.

http://music-electronics-forum.com//...ad.php?t=11796

[Mandopicker]

If you really want to locate the screws in a similar location as Fender, you might try and find images of a vintage 5E3 for the relative screw position. In truth being exact doesn't really matter other than for vintage asthetics.

Either way...

If using sheet metal or self tapping screw type, mark the chassis and drill pilot holes smaller than the screws themselves. You do not have to use that type of screw as a screw/nut combination would do just as well.

Hint...position the board inside the chassis so that the screws can be reached with the board fully populated. This will make future repairs and removal easier withour removing parts. Mark the holes to match the predrilld chassis and drill through both the board and the backing board.

* I would find these locations before you solder everything to the board (Dry fit to be sure.) Not necessary but perhaps good form.

No need for stand-offs.

Hope this helps.

[mbratch]

Thanks guys.

For some reason, when I first looked at pics of vintage 5E3's I didn't see the mounting screws. Looking back, I do see them now. I think I need new glasses.

So that all makes perfect sense.

I think stand-offs are necessary for the "hard", single turret board designs I've seen occasionally.

I'm excited about getting started on this...

[tubeswell]

FWIW I use spacer nuts between the board and the chassis

[Mandopicker]

Here are just a few obveservations I have made after making several amps or varying design.

IMO stand-offs seem to be better utilized when the main board is used without a backing board. Not to say that it cannot be used with a double layer design, but the whole purpose of the second layer is to insulate the connections from the chassis, and to perhaps even keep wires sandwiched in their place and vibrations to a minimum. (I have seen higher gain amps with only two spacer towers used, so to speak, that allowed the board to vibrate causing rattling or other related noises.) If using spacers, I would suggest supporting the board at 4 corners to alleviate that vibration potential. I have used thin phenolic material with 10mm spacers and no backing board knowing that the wires were significantly insulated from any possible chassis connection, and vibrations were minimized.

Either way is good if it is what you choose to do. Just consider that in a traditional 5E3 chassis design, the higher you raise the board off the chassis, the closer you bring some connections to input jacks and other areas that could cause oscillations. Just think the design through carefully so you don't have to take it all out again and start over.

I also suspect that Leo chose a thin two layer design attached by self tapping screws for simplicity, and cost saving measures. By not having to purchase large quantities of spacers, washers, and nuts, Fender probably saved thousands. The board material probably cost very little in relation.

Not trying to preach, but perhaps these thoughts are useful.

[Ben]

Hi all,

First post. First time builder. Mojo 5E3 kits just arrived last friday and i too was wondering how the eyelet board attached. Some of my questions were answered in this thread and the one linked, but i was wondering about a couple things.

1. whats the proper spacing between the eyelet board and the insulating board? are they flat up against each other or is there a standard spacing?
2. how far should the insulating board be from the chassis? or maybe it should be flush up against the chassis? I mean how much space should be between the planes made by the insulating board and chassis, not how far should it be from the right end of the chassis.
3. my parts list has a line that reads "tweed chassis screws". are these the screws I'm supposed to use? or does anyone know if the mojo kits come with hardware for mounting the eyelet board and if so ..which peice is it?


thanks for the help!

[Resonator Guy]

Ben, I just used a little guesswork and logic on the spacing.
I used a couple of pieces of insulation from the PT wires between the two boards with the two screws through the insulation and the holes I drilled.
I figured you just need enough space so as not to crush the wires between the boards.
I put the bottom board flush on the chassis, because it pretty much had to be that short to clear all the other equipment, especially the input jacks.
I didn't get any screws but used appropriate length sheet metal screws and they seem to be working well.
The amp works and sounds terrific. I took it out for the first time to a Blues jam last Friday night. I did take a backup but didn't need to as it performed admirably.
Hope that answers your questions. Good luck.

[tubeswell]

Hi Ben welcome to the forum

Originally Posted by Ben

Hi all,
1. whats the proper spacing between the eyelet board and the insulating board? are they flat up against each other or is there a standard spacing?

No 'proper' spacing. The insulating board doesn't perform any EMF blocking function, so you can put it however close/far away you want from the main board. Most peeps sammy it right behind the main board (allowing a bit of space for a few wires). I never bother with them personally - I just use spacer nuts from the main board to the chassis and use insulated wire for back of the board stuff.

Originally Posted by Ben

2. how far should the insulating board be from the chassis? or maybe it should be flush up against the chassis? I mean how much space should be between the planes made by the insulating board and chassis, not how far should it be from the right end of the chassis.

Same sort of answer as for 1. (above)

Originally Posted by Ben

3. my parts list has a line that reads "tweed chassis screws". are these the screws I'm supposed to use? or does anyone know if the mojo kits come with hardware for mounting the eyelet board and if so ..which peice is it?

If there aren't any mounting bolts in the kit, go down to your local electronics store and get some small bolts and nuts with some assorted spacer nuts. Probably quicker in the long run than waiting for them to arrive in the mail. Get the tranny mounting bolts and the chassis mounting bolts while you're there

[Ben]

Thanks guys,

There are alot of nuts and bolts that came with this kit, thats the problem..none of em really say what they are for. Reso Guy, was your kit a mojo and did it come with any hardware at all, or just no moutning hardware for the board?

I'm trying to figure out if i already have the hardware. I guess i could wait till the cabinet arrives and do a dry run and see whats left over hardware wise, but i wanted to get started.
All the other holes for this kit are pre-drilled. It would seem to me that everyne would want to put the board in the same place, as per vintage spec, I wonder why then these holes arent pre drilled for me just like the others?

Oh well, thanks again for the help, I understand about the spacing and will figure out the hardware or just use my own hardware to mount it. Unless.. anyone has built a mojo kit and remembers the screw size , or even if the kit came with that hardware?
Cheers!
-Ben

[Resonator Guy]

Hey Ben, mine is a mojo kit and it came with all the hardware except the sheet metal screws for the board. The mounting holes in the cab for the chassis weren't drilled either. You will need another person to help you line that up for drilling if yours isn't done.
BNWitt told me to use panhead #8 self tapping metal screws. Check this thread. There are some good pictures and explanations there.

Mounting Mojo 5E3 Tag Board

[Ben]

Thanks again for all the help.

My plan is to use the self tapping #8 panhead screws, two of them, with no spacers at all betwen the boards, nor between the chassis and the boards.
My thinking is that the wires will provide the necessary spacing betwen the two boards, and that the insulated board can be flush against the chassis with no space. I think this is how Fender did it?

If anyone thinks this is a bad idea, or has any additional suggestions or comments, that would be most helpful. I plan on drilling tomorrow and am gonna try a dry run of mounting everything i can first to make sure I have good fit and spacing....before i begin populating the board.

Thanks again all the help, what anexcellent forum!
Cheers
-Ben

[mbratch]

Originally Posted by Ben

My plan is to use the self tapping #8 panhead screws, two of them, with no spacers at all betwen the boards, nor between the chassis and the boards.

My thinking is that the wires will provide the necessary spacing betwen the two boards, and that the insulated board can be flush against the chassis with no space. I think this is how Fender did it?

I also have the Mojo kit. Like the vintage Fenders, there should be a blank board that has the same dimensions as the eyelet board included in the kit. That board goes between the eyelet board and the chassis to insulate it. You do not want to mount the eyelet board without it. You need the insulator board, or PCB spacers. But a standard eyelet board uses the insulator board, as is done in the vintage Fenders.

As far as screws, you can use really whatever you like. Originally, I used two spare screws and nuts that came with the kit (the kit supplies plenty). But the spare screws were a little long so I went and bought some shorter ones. You can also use self-tapping, which is what the original amps used. I wanted to do that, but had trouble finding self-tapping. They seem to have gone the way of the Do-Do Bird in favor of self-drilling.

For placement, I looked at a few pics of vintage Fenders and located them in the same place as those. But any two reasonably spaced locations will work as long as you don't drill through a wire.

[Ben]

Thanks mbratch!

The hardware in the mojo kit was a mystery to me. I have 8 6-32 nuts and bolts that dont seem to fit anywhere. I was hoping they were for the tube sockets but they dont fit. i have nothing to mount the tube sockets with now, so i gues I wll be going ot the hardware store AGAIN. annoying. Dear Mojo, I paid $700 , please proved the 50 cents worth of nuts and bolts necessary to asemble this thing!

As for mounting the boards, there were NO screws of any sort appropriate for this. I went to the hardware store and bought self drilling ...assuming that they were the same as self tapping. Drilled a small pilot hole and behold...they actually did tap a nice threaded hole in my chassis. they work perfectly.

Unfortunately, I ran out of cloth covered wire..and now have to wait for mojo to send more. again, a couple extra feet of wire costs what? 60 cents?

if i do this agin i will try Mission.

Thanks for the help everyone. If anyone has any grounding tips (see my proposed scheme above) that would be great. while I wait for my wire...ungh.

[Resonator Guy]

Hey Ben, the nuts and bolts I got with mine (more nuts than bolts) did fit the tube sockets. I used them there and to bolt down a terminal strip I used for part of my grounds. One of the pots I received was broken, too. I did get plenty of wire though.

You will end up with a great sounding amp so keep at it.

[tubeswell]

Hi Ben - I sent you a PM on this

[mbratch]

Ben -- not sure what happened with your kit. I had green and white wire to spare when I was done. I did, however, "measure" it out carefully and tried not to waste any along the way, planning the wiring as I went. If you aren't careful to do that, you can waste it a way an inch or two at a time.

Nuts/screws and bolts: I had spare of those as well after I was done. I don't recall what size fit the tube sockets. I used two provided screw/bolt pairs to hold the eyelet board in. But I bought shorter ones since I didn't like how far they stuck out (I'm anal, I know). The self drilling screws work even without a pilot hole, I just didn't like that pointy tip stick out the back of the chassis waiting for me to poke/gouge my finger on it one day. Self tapping screws need to be predrilled, but they have a blunt end. However, they don't seem to be available any more.

I hope you get your parts sorted out! Mike at Mojo is a good guy and he'll help you out.

[Resonator Guy]

Yep, the guys at Mojo always helped me out, Sean in Customer Service especially.
I do agree it can be frustrating working on your own out there, but it will all come together at some point.

[Baxtercat]

I used to mount those little fishboards all day long [along with the other parts].

Working at Fender (or I decided to get a 'real job') ...by Guitar Bob Ohsiek

The insulator and the circuit board were predrilled w/ the two holes. It was so easy to zip 'em both to the chassis w two screws. Spacers would've been cooler for sure [or wiring the amp like a Hiwatt!] but it was all about saving time and money.

Whenever I get inside to fix an old one now the problem is so often rusty or otherwise bad connex under the tremelo bug. Sometimes just a new insulator slipped under there fixes it.

Check out the rusted old Showman I just rebuilt.
"How many amps do you need, babe?" "Just one more." The OD Twanger 85 ...by Guitar Bob Ohsiek

[mbratch]

Baxtercat, that is so cool.

I laid my eyelet board and insulator board inside the chassis, lined them up where I wanted them, and drilled the two holes straight through both boards and chassis. After drilling the first hole I screwed that one down, then did the second to hold it steady.

[tubeswell]

Welcome to the forum Baxtercat/Bob. That homebrewed 85 Wer is cool. I look forward to more of your stories about working for CBS

[Ben]

That is too cool Baxter!

Ive always felt a special connection to fender instruments and amps.
Building my first amp, one modeled after one of Leo's designs, what really appeals to me is the simplicity and logic of the design. The economy and functionality of the eyelet board mouting is a good example.

Well guys, the cloth wire came yesterday (thanks mojo!) and I got the board done and mounted and it looks great! or at least i think so!
I wired the tube sockets and did my heater wiring.

That leaves the jacks + preamp grounding.
The transformers. The switch and ac chord wiring, the pots, and the speaker jacks.

1. One thing i am still really confused on and dont know what to do abut is the .047 cap coming of the ground switch. A freind told me to ditch this cap (called it a deathcap, which i have heard is undesirable). If i do that, surely the wiring must be changed also?

2. Im looking for jack shots/photos to see how others do it. ditto speaker jck wiring. Im having the preamp ground and ground from 12ax7 pin 3, after it pases thru cap/resistor go the ground of input jack#1.

thanks again for the help, she's almost done! (I think?)

[mbratch]

Originally Posted by Ben

1. One thing i am still really confused on and dont know what to do abut is the .047 cap coming of the ground switch. A freind told me to ditch this cap (called it a deathcap, which i have heard is undesirable). If i do that, surely the wiring must be changed also?

After I got over being anal about keeping my amp true-to-vintage in favor of being safer, I changed my ground switch to a standby switch. Just bypass the switch for the power wiring and use it instead to switch the HV center tap to ground wire. That makes a perfectly good standby for the 5E3. Since the 5E3 doesn't really need a standby, there are probably other clever things you can do. I think some builders keep it there for vintage look but it does nothing.

Originally Posted by Ben

2. Im looking for jack shots/photos to see how others do it. ditto speaker jck wiring. Im having the preamp ground and ground from 12ax7 pin 3, after it pases thru cap/resistor go the ground of input jack#1.

Here are some pics of my build.

Originally Posted by Ben

thanks again for the help, she's almost done! (I think?)

Hah! You think so? You'll have fun trying different mods once it's done. At least I have. I didn't think I would bother, but there are a few enhancers that are interesting.

[Ben]

heres how i did the jacks.
I dont understand why some connect all the jacks grounds to each other with separate wires. arent they automatically grounded by touching the chassis? As you can see I didnt connect the grounds to each other, juts grounded the two boards preamp grounds to the ground on input #1 and let thatc ground itself to the chassis by contact only. is this wrong?
these are switchcraft "shorting jacks" if that makes any diff. mojo kit, again.

Okay, i want to ditch that deathcap, but didnt understand your explanation of the new wiring shceme mbratch. Im unfamiliar with terms like "hv center tap". my apologies. do I need a new switch or can i use the ground switch wired differently?

[tubeswell]

Originally Posted by Ben

Im unfamiliar with terms like "hv center tap".

HV (or 'HT' for proper english-speaking countries ) centre tap is the Power Transformer's High-Voltage winding centre tap.

If you are taking out the death cap (which you should BTW), then yes take out any associated alternate-ground switch, and make sure the amp is wired with an up-to-date 3-wire mains system (including mains earth, which is permanently bolted to the chassis)

[mbratch]

Ben -- there are some long threads on grounding schemes for the 5E3, and lots of controversy over what's the "best". But there is consensus on one thing: if your scheme works, then it's good. So relying on the chassis for ground is OK for the jacks as long as it doesn't cause any ground loops and give you undesirable hum. Fender used a big brass plate behind the control panel.

For the ground switch, I agree with tubeswell. The simplest thing to do, as I mentioned, is just ignore it. Don't wire it up and have it do nothing. Just connect the hot, neutral straight through bypassing the switch. You could use the unused switch for something else, like standby, but it's not required for this amp. There are a couple of standby schemes. The ... erm.... HT center tap is red/yellow stripe wire connected to ground per the mojo diagram. One way to do standby is to connect it through the switch so that it is either grounded (on) or not (standby).

[Ben]

So ignore the ground switch. Then my white ac chord goes to one pole of the ppower switch, the other pole of the switch gets one of the black wires from the PT?
The other black wire from the PT will go to the fuse and the black wire from the ac chord will also go to the fuse. Is this correct? Does it matter which prong on the fuse gets which black wire? my fuse has one lug on its side and one on the tip.


Here is how i did my jacks. I understand that whatever works is the 'right" way. But having never built an amp before, the best I can do is look at what has worked for others. So when i see alot of others grounding their jacks, even tho i know them to be grounded already by contacting ther chassis...I wonder if "maybe THIS is the way that works?". also Im afraid of shocking myself somehow...thats probably not a legit concern with an ungrounded input jack...but since I know next to nothing ...I fear doing things in a manner other than how i see everyone else doing them.
anyway, I didnt ground the jacks figuring they are grounded to chassis already and adding another wire would just be making another ground loop.
whats puzzling for me is, I see lots of diagrams where they do chain all the jack grounds together. maybe they are using insulated jacks?
heres an artsy shot of the jacks(finally figured out how the close up function on my camera works...and gee Ive only had it for 4 years now)

hey guys, I cant thank you enough for the help and encouragement. I think i might be able to fire it up today if i can get these last couple questions taken care of.

[mbratch]

Ben -- regarding the ground switch you could simply just disconnect (remove) the cap and be done. The ground switch will then just be a terminal post for the wires.

As far as grounding jacks, I've seen it both ways. Typically, though, when builders have grounded the jacks to the chassis, they've used the brass plate that the vintage amps used. Mojo doesn't provide those. So I chose a different scheme to ground the jacks. However, yours may still work fine. You just have to try it. There's no more risk of shock in that case than if you use a brass plate as long as you didn't wire power to the chassis.

I don't see the rest of your wiring, so hard to comment on what one might expect. Where are you tying your other ground points (e.g., the cathode cap/resistor grounds from the circuit)?

Nice pics, btw. And your wiring looks nice and neat.

[Ben]

Thanks for the compliment on the wiring!

on the ground switch, if its non functional, Id rather simply not connect it if at all possible. My thinking is that every connection and component, unless absolutely essiential, is just another chnace for degradation of signal...maybe thats not correct but i infer this from noticing that my favorite sounding amps are often the ones with the fewest components, knobs, switches, etc.

1. could I wire it up as proposed above without the ground switch? This is one part i REALLY wanna get right. I dont wanna flip that power switch and get zapped or zorch my components.
2. does it matter which lug of the fuse gets which black wire(either from PT or ac chord?)? again, my fuse has a flip up lug in the middle of the fuse holder and one big round lug on the tip
3. The black wire from the OT was not shown on the wiring diagram. I wired ti to ground of my speaker jack. is this correct?

Thanks again mbratch! and everyone else!
-Ben

edit for photos

fuse holder


remaining PT and ac chord wiring, switch on far left is unused ground.

[mbratch]

Originally Posted by Ben

1. could I wire it up as proposed above without the ground switch? This is one part i REALLY wanna get right. I dont wanna flip that power switch and get zapped or zorch my components.

Ah, I see. I didn't realize your ground wasn't already wired up. Run the black wire from the power cord to one tab on the fuse (doesn't matter which tab). Then the other tab of the fuse to one of the black twisted wires from the PT. Then connect the other black twisted wire from the PT to the white wire from the power cord using a wire nut.

2. does it matter which lug of the fuse gets which black wire(either from PT or ac chord?)? again, my fuse has a flip up lug in the middle of the fuse holder and one big round lug on the tip

Doesn't matter. Neither the fuse nor the holder has an electronic polarity.

3. The black wire from the OT was not shown on the wiring diagram. I wired tied to ground of my speaker jack. is this correct?

Yes. The mojo schematic is like the vintage schematic. But on the vintage amps, the ground wire from the OT was a bare wire that came from the coil and was soldered directly to the OT casing, which was then grounded to the chassis, and the output jack grounds to the chassis. With the mojo OT, you just connect the black wire directly to the jack ground.

[Ben]

Originally Posted by mbratch

Ah, I see. I didn't realize your ground wasn't already wired up. Run the black wire from the power cord to one tab on the fuse (doesn't matter which tab). Then the other tab of the fuse to one of the black twisted wires from the PT. Then connect the other black twisted wire from the PT to the white wire from the power cord using a wire nut.
Doesn't matter. Neither the fuse nor the holder has an electronic polarity.
Yes. The mojo schematic is like the vintage schematic. But on the vintage amps, the ground wire from the OT was a bare wire that came from the coil and was soldered directly to the OT casing, which was then grounded to the chassis, and the output jack grounds to the chassis. With the mojo OT, you just connect the black wire directly to the jack ground.

on #1, where is the power switch? between the white chord and PT black wire, yes? it doesnt need to be connected in series with the fuse? thanks!


Thanks!

[tubeswell]

Originally Posted by mbratch

Doesn't matter. Neither the fuse nor the holder has an electronic polarity.

Actually for safety its better to run the mains active wire straight to the bottom tab of the fuse holder. If for some reason if you ever have the amp plugged in and the cap off the fuse holder, you don't want the ring terminal under the fuse holder's cap to be live.

[Ben]

Im stilluncertain how to wire it.

How bout this?:
white ac chord wire goes to first black PT wire with wire nut. Black ac chord wire goes to lug on tip of fuse holder. jumper runs from other lug on fuse holder to switch, remaining black PT wire goes to remaing open power switch lug.

Is this correct and SAFE?
Green wire from ac chord is of course grounded to chassis under PT bolt.

thanks again for the help, i really appreciate it!

[tubeswell]

Hi Ben

the wire colouring is different in this neck of the woods, so black and white doesn't mean that much to me. (Hey that's a good line for a song!)

Whichever is the active/phase wire goes to the bottom of the fuse holder, then from the top of the fuse holder to the main switch, then to the corresponding coloured wire on the PT (white-to white, black to black). Whichever wire is the neutral mains wire goes straight to the PT. Try googling up a mains wire colour page for your locality and see what it says.

(Edit - seeing as how you have two black wires coming out of the PT cover going nowhere in your pic, I take it that those are your primaries - doesn't matter which one you pick for which incoming wire.

[Ben]

Oh man....IT WORKS!
I am beside myself with joy right now.

It sounds awesome. It is nice and quiet too.
Thank you all so much for the help.

There is one issue so far.
This is hard for me to explain becuase I dont fully understand how the volume knobs interact, but I get some oscillation with both volume knobs on 12 and the middle pot (volume) will pop loudly when I turn to to 12 sometimes, depending on wether im plugged into the bright or normal channels. It almost sound like there is crud in the pot at teh twelve oclock spot on that pot, except its a real loud crackling popping kind of sound, not a scratchy pot sound.
heres a shot of the pot wiring. is it possible for a ittle bit of solder cliping to fall into the gap in these pots and cause this crackling sound? It rally is lik a bad connection sound but only at 12 on the dial and only on this one pot.
The oscialltion i get on both normal and bright channels it seems and with or withou a guitar plugged in also.

Im stoked that it works and sounds so great for the most part tho! wahoo!