5E3 Tweed Build - Normal Channel Not Working

[TubeJunkie]

HELP!!! 

I finished a 5E3 Tweed Deluxe build a few weeks ago, and I'm getting nothing from the Normal channel – dead silence, except for a little amp noise through the speaker – from both the Hi & Lo inputs.  When I turn both of the volumes up and down, the little bit of speaker hiss gets louder and quieter, but I get nothing from the jacks/guitar.  However, I'm getting some very sweet and awesome tone from both inputs of the Bright channel.  I have gone over every single wire, connection, and solder joint, traced wiring, done continuity tests to make sure wires are starting and ending where they should, and to check for proper and improper grounding, and that includes the tube sockets.  At first, I thought it was the coupling cap from V1 (normal channel side), so I removed it, and measured the capacitance . . . it didn't have any.  I replaced it with a new cap (measured it first), fired it up again, and the same thing – silence.  I removed the same cap again, and tested it, and it tested just fine, so I soldered it back into place, fired it up again, and once again, the same thing – silence.  Could both input jacks be bad?  I did continuity tests on both Normal channel jacks, and everything tested fine.  Since they're passive devices, there's not much voltage to measure.  Both volume pots work with the Bright channel – the Bright volume goes loud and soft, and the Normal volume cuts out the Bright volume when turned all the way up – so I don't believe it's a bad Normal channel volume pot, because I tested it's resistance from 0 ohms to 1M ohms, and tested ground as well, and it tested good (I could be wrong though).  I swapped the tubes back and forth between V1 and V2, tried two more tubes in V1, and still nothing.  I went through and measured all the tube and B+ voltages, and I've attached a pic of the measured voltages.  I did the "chop-stick" test, and poked around with an orange stick, but didn't find any loose connections, or find any connections that snapped-crackled-or-popped (yes, I did keep one hand in my pocket at all times).

I'm at a loss.  Is there any way to test the signal within the circuit, to find where the signal is being dropped?  I've been through every troubleshooting manual I can find, and searched the internet, but nothing has helped.  I've also attached pics of the wiring, a layout of how I wired the input jacks, and the layout I used for the build (I did change it from non-shielded to shielded wiring from jacks to V1).  Am I overlooking something?  Any help would be greatly appreciated . . . thanks in advance.

NOTE:  I had to use multiple posts to get all the pics uploaded . . . this post has voltages.

[TubeJunkie]

This post has 2 pics of the amp's innards . . .

[TubeJunkie]

This post has 2 more pics of the amp's innards . . .

[TubeJunkie]

This post has 2 pics of the amp's innards . . .

[TubeJunkie]

Again, 2 more pics of the amp's innards . . .

[TubeJunkie]

And finally, the last 2 pics of the amp's innards . . .

[TubeJunkie]

Okay, so the final two pics . . . the Input Jacks Layout, and the Full Layout used for the build (Thanks Rob).

[sluckey]

There is so little circuitry involved that it almost has to be a wiring error or bad wire. I would not suspect the jacks but they could be miswired. Try this...

I want you to swap the input jacks, ie. connect the bright jacks to v1-2 and connect the normal jacks to v1-7. This is easy to do. Just swap the shielded cables right on the v1 socket.

Now do the bright jacks work thru the normal channel? Do the normal jacks work thru the bright channel?

and the Normal volume cuts out the Bright volume when turned all the way up

Are you saying the normal volume can totally kill all sound from the bright channel? If so, that ain't right.

[PRR]

> the Normal volume cuts out the Bright volume when turned all the way up

Short to ground near Norm Vol wiper.

[sluckey]

Short to ground near Norm Vol wiper.

Aha! That would explain everything.

[TubeJunkie]

First, I want to thank everyone who put in their $0.02 cents worth – actually it was all much more valuable than that, because I wouldn't have found the problem without everyone's help.  But as a result, I now have a greater breadth and depth of knowledge about building and trouble-shooting amps, so again thanks.  Also, I want to apologize for not responding to everyone's posts/suggestions sooner.  It's been a crazy week at work (I'm a teacher, and it's the end of the school year), and so didn't get a chance to try anything until today, and I've been working on it for the last couple of hours, going through everyone's suggestions.  The result is . . .

PROBLEM SOLVED!!!!         

From the suggestions on the Telecaster Guitar Forum, I again measured voltages, resistance, and continuity at all the point suggested, I couldn't find anything wrong. I measured resistances like Nickfl, Preacher and philosofriend suggested, and everything measured really good – within the ranges they mentioned.  As philo also suggested, I again checked speaker response with nothing plugged in, and the slight speaker-hiss went up and down when the volume knobs were turned up and down.  I also removed V1 and measured the resistance between the inside of the pin sockets of p3 & p8, and got 0.2 ohms.  All still good, and thanks to corliss1, I now have my own home-brewed signal tracer.

From the Les Paul Forum, as suggested – thanks Case24, Wrench66, and Pappy58 – I  double checked the heater connections and turned out the lights to make sure V1 was heating up properly.  Tubes looked good, and both triodes were glowing nicely.  I checked continuity of the center conductor of the shielded cable, and continuity through pin 2 of V1's tube socket.  It was also suggested to check if the normal channel's shielded wire center connector was shorting to ground.  I did, and it checked fine.  So for everything is checking properly . . . CRAP!!!! . . . (not what I really said).

On The Gear Page Forum and the Hoffman Amplifiers Forum – thanks HotBluePlates, oldhousescott, Rockinrob86, zenas, VaughnC, Winnie Thomas, 66 Kicks, sluckey, and PRR  for your input – I tried the suggestions of measuring voltage with the guitar plugged it at the normal channel plate – voltage was fine. Triple-checked the input wiring, and again everything looks good. Checked the pots again – everything checked out, and amp sound/hiss through the speaker went up and as it should with the volume pots turned up and down.  Also, I checked all grounding wires and looked for cross-contact, and again everything looked and tested just fine.  Unfortunately, I don't have a signal generator or oscilloscope to do the other tests; and I didn't get to the suggestion of using a second amp (suggested by a couple of posters in other forums as well).

I was going to try sluckey's suggestion of swapping the normal and bright inputs on V1, and I remembered the comment from "The Ballzz" on the Les Paul Forum, " Why the shielded cable? I agree it's the most probable cause, and not needed at all. I've built a half dozen tweed kits and never used it."  This was my first build with shielded cable, so I decided to remove it from the normal channel and replace it with plain old cloth push-back wire when I did the V1 swap between normal and bright.  Just before I pulled it out, I tested the center conductor to ground one more time before removing it, and voilà – the center conductor was grounding out!!!  I pulled out the shielded cable, and I found a single tiny strand of cable wire with a little solder at the bottom of Pin 2.  It was going over towards Pin 1, and I didn't see it because the shielded cable was blocking it!!!  Apparently, every time I took measurements with V1 out, there was no grounding.  But when I plugged the tube in, the sockets would move and the little strand would make contact between Pin 3 and Pin 1, grounding it out.

Long story short (too late for that I guess), I cleaned off all the solder and wire strands from Pin 2's solder connector, soldered in the non-shielded wire between V1 and the normal channel jacks, and the problem was solved.  Along the way I learned a few new things, got a new piece of test equipment for my bench – you can never have too many tools (unless you ask my wife) – and best of all, I have an awesome tone machine with the 5E3.  It sounds amazing, and will now be played and played until my wife complains, at which time I'll turn it down and keep playing . . . now for my next amp, I'm going to build a British-style 18 watt 1 x 12 with . . .

Again THANKS TO ALL!!!

[newguitarsmell]

I did a 5e3 build and had troubles with those shielded wires, too. No noise from replacing them with unshielded?
I just finished an 18w 6v6 plexi and had some issues (I posted about it here). We should compare notes... if you'd like!

[TubeJunkie]

I did a 5e3 build and had troubles with those shielded wires, too. No noise from replacing them with unshielded?
I just finished an 18w 6v6 plexi and had some issues (I posted about it here). We should compare notes... if you'd like!

Sorry, for some reason the forum changed my notification settings so I didn't see this.

No, no discernible increase in noise.  My next build was going to be a British 18 Watt styled after the Mojotone design, but I sourced all my own parts, because quite often a kit is more "economical" than "built for tone" when they pick the parts.  I came across a write-up where the Mojo kit was compared to the TubeDepot kit:

   https://www.premierguitar.com/articles/20990-the-mean-18-british-style-18-watt-amp-kits-from-mojotone-and-tube-depot

Here's what the author said:

"I prefer the Mojotone’s sound. There’s more of a bell-like quality to the clean tones, and when you pour on the gain, everything resonates a bit more sweetly, with fewer harsh and chaotic overtones. It doesn’t emit more low end per-se, but the fundamental frequencies seem weightier. I dig this taut, focused character.  This is a subjective call, however, so judge for yourself . . . I attribute the sonic differences to internal components—but attempting to pinpoint which component is responsible for what is the sort of thing that launches flame wars on amp sites."

That's what swung me.

Mojotone's instructions are sparse - and that's being generous with the word sparse: a layout, a schematic, and instructions - 6 pages, but mostly just pictures.  However, I did "borrow" TubeDepot's instruction manual, which is 71 pages long, very detailed, and does explain that there are a couple of places where shielded cable is recommended, and they actually provide the cable with their kit, that's how important they think it is.  I will probably use shielded cable in those places, but unless there is any noticeable difference, I'll use cloth-covered push-back wire from the inputs to the first pre-amp tube (I like it better than the plastic/teflon coated).  The Mojo kit recommends shielded cable for the vibrato/tremolo footswitch, and there is a capacitor on the Mojo layout that has a recommended alternate position to reduce noise, which I will be incorporating as well.  From what I've heard/read, the 18 Watt and Plexi 6V6 are prone to noise, and is usually the way wire is run, and that shielded wire is more necessary because of the layout.  Did you use a kit, or do more of a DIY build?

I'd be happy to compare notes; however, I'm sidetracked from that build right now.  My son (drums, piano, bass), is going to start performing this summer, so I'm building him a Bass Tube Amp Head to go with a Fender Rumble 115 cab that I got used - in excelent shape - for $200 (half the new price).  Let me know what you'd like to discuss!!


 The Mojo docs are here (scroll down):

   https://www.mojotone.com/kits/BritishAmpKits_x/Mojotone-British-18-Watt-Style-1x12-Combo-Amplifier-Kit_2

[vampwizzard]

I built a tremolux with no shielded input wires. It was pretty quiet. Same on my PP el84. That is more likely due to luck than to skill. Theres a certain length of wire you can run before youre almost assured to get noise.

Have you considered Doug's Stout and Marshall progression amps from here? They're a little better sounding IMO and the kinks have already been worked out compared to many of the kits. Ive got a third AO-43 conversion that ive earmarked for one of those.

[TubeJunkie]

I started with straight kits, but then did a scratch-build of a 2-stroke, and I liked the challenge of not just building someone else's idea of what parts should be in an amp.  I've looked at a lot of variations of layouts, Doug's and Rob Robinette's to name a couple, and built a couple scratch-builds like that, but my leanings, however, are going in a different direction now - I'm looking at vintage amps that aren't in a kit of any kind.  For example, I have a Supro Thunderbolt that I'm in the planning stages on, but I'm adding a little twist.  I read an article by Jeff Bober, who used to write for PremierGuitar, and worked with him and came up with a design that cascades the unused triode of V1.  I'm also working out the details of a National/Valco Model 1215 Professional that uses 6SL7s, 6SN7s, 6SJ7s, a 5U4GB, and I'm going to throw in a couple of NOS Russian 6P3S-Es, and run them a little hot (~350V).  The first hurdle, was how to provide 6.3Vdc heater voltage, but these tubes require 4.9A,  I couldn't find a conventional guitar amp power transformer, so I got creative and after a lot of searching, found a Hammond transformer that is a single purpose 115/120V to 6.3V @ 6A.  I'll run that with a conventional PT for the rectifier and B+ voltages.  Another one I'm working on has a Princeton Deluxe pre-amp with a Blues Jr. PI and EL84 tube output, beefed up to run at ~20 watts.  I'm also considering doing a scratch build of a Fender Excelsior.  I already have all the parts for that, and I like the vintage vibe of the excelsior.  So far, everything has been very quiet, but then I'm a little OCD - uh, very detail oriented, so I spend a lot of time making sure everything is done right the first time . . . well except for this last 5E3 . . . and I blame the #$%*&@ gremlin that put that little wire in the wrong place!   

Here's a link to a McKinney/National/Valco model 1260 that's very similar to the model 1215:

   https://www.youtube.com/watch?v=2sl2KrKm3O0&feature=youtu.be

Go to about the 5:05 mark, that's what I'm liking, but I do also like the clean.   

[mebond11]

I built a stewmac 5e3 kit (which seems to be a rebadged mojotone) and a Trinity Amps 5e3 kit.   The Trinity kit had shielded cable, a superior star grounding scheme, isolated jacks, and better components.  However, both kits were quiet.   If I turn volumes and tone up to maximum with no input signal, the trinity kit is maybe half as loud, but the sound is so minimal in both that I don’t think you would ever notice the difference in normal use.

The shielded cable is a bit of pain to work with...I put heat shrink around the non-grounded end of the shield to avoid any stray grounding wire shorting something out.

[dude]

So Sluckey and PPR we’re right a short

[Mr. P ~]

Sounds a lot like a BMW 2002 story with a carburetor and a tiny piece of rubber gasket! 

[TubeJunkie]

What's a carburetor??!!

I can relate . . . my story is about a carburetor with a pin-hole in the float.  It would slowly fill with fuel, drop and flood the engine, and then drain by the time I tore the $%#$& carburetor apart . . . ahhh, those were the days . . .

[PRR]

> pin-hole in the float

Standard practice was to boil a pot of water and throw the float in. Bubbles mean troubles. (The hot water expands the cool air; a pot of cold water won't excite a very small leak due to surface tension.)

[TubeJunkie]

Yup, that's the test I did . . .