Filament wiring

[blodviol]

Hi, everyone.

This is my first thread here. And my first build.

I'm building a Weber 5E3 head, and i've been following the layout on their web page. I live in norway, so i chose the EU PT. but that's probably not important here...

I'm confused 'cause on the weber layout there seems to be two green wires to go to the filaments, but on the Fender version (which i got off of FFG), one filament pin on each tube is grounded. And from the Fender schematic it looks like one of the green wires should go directly to ground. I guess fender is right. afterall, their amps had been working for thirty-forty years before anyone started copying them. it shouldn't make much of a difference, i guess, i'd have to ground somewhere anyway, right?

Tríste

[MWJB]

Your Weber PT should have a filament centre tap (usually green/yellow), ground this. The original '59 PT did not.

Use the 2x green wires to all your tubes, it's best to make sure that the wire running to pin 2 of one power tube also runs to pin 2 of the next power tube for hum reduction, pin 7 V3 goes to pin 7 V4 etc. Keeping this polarity is not necessary for the preamp tube filaments.

Yes, Fender deluxes worked OK but their decision was most likely based on keeping costs & build time to a minimum...a big consideration if you are building tens of thousands of amps. You are just building one and you want it to work properly & quietly, first time, so use the 2 wire method.

[Tom Phillips]

The heater wiring shown in the Weber drawing is considered an upgrade. You will do best to follow the Weber drawing. The green/yellow wire from the power transformer is the center tap of the 6.3V winding. You will see it grounded to the chassis and that is how the heater circuit in your amp will get it's ground reference. If you also ground one of the green wires it will cause a short circuit to the green/yellow wire. Fender did not ground one side of the heater circuit to the chassis in their better amps.

[blodviol]

Wow, that's a fast response..

Thanx, Tríste

[blodviol]

Now i've finished the kit, and it works, kind of. but there is not very much volume. Posted on debugging 'bout this.

[blodviol]

Should the green and black wire coming from the OT be connected internally in the OT? 'Cuz they are. thinking that might be a problem...

[Tom Phillips]

Should the green and black wire coming from the OT be connected internally in the OT? 'Cuz they are. thinking that might be a problem...

No they should not but if you are trying to measure continuity after the PT is installed in the circuit per the wiring layout at http://www.weberspeakers.com/store/5e3_layout.jpg they may appear to be connected. This is because the black wire is connected to the chassis AND the heater center tap green/yellow wire is also connected to the chassis. There is a very low resistance between the green/yellow wire and either of the green wires.
Make sense?
Regards,
Tom

[blodviol]

No they should not but if you are trying to measure continuity after the PT is installed in the circuit per the wiring layout at http://www.weberspeakers.com/store/5e3_layout.jpg they may appear to be connected. This is because the black wire is connected to the chassis AND the heater center tap green/yellow wire is also connected to the chassis. There is a very low resistance between the green/yellow wire and either of the green wires.
Make sense?
Regards,
Tom

Yeah, i disconnected the jacks and checked it. i just checked for a connection. It reads 0.7 ohms between red and green.

[blodviol]

found it!

for some strange reason, the wire from pin 4 on the 6V6's weren't connected at all. That did the trick. Maybe i never did it, or maybe it came loose later. dunno.

So now it works, and it's loud... Heheh. But it has a rather annoying hum, which gets louder as i turn up the volume, but gets buried while playing at full tilt, though absolutely detectable at lower volumes. The hum is also, curiously, an octave lower on the normal channel than on the high. guess the "bright-cap" is filtering the 100Hz altogether. (220V 50Hz mains here in Europe)

Any thoughts on this? would it help to change the two leftmost 16uF caps to 20uF? I see other people have done this, or might the problem lie elsewhere?

Tríste

[stokes]

In the case of the Eur.AC when your 50hz AC is rectified it becomes 100hz,so it is very possible some increased filtering would help.But going to 20uf from 16uf wont make much difference,try 40uf.By the 2 leftmost 16uf caps,you are refering to the main supply ans screen supply,yes these are the ones to adjust,dont change the one going to your preamps.

[Bruce / Mission Amps]

Build it using the WeberVST layout.
Ground the green/yellow wire as shown on the layout and the other solid green filament wires to the tube sockets.
It does make a little difference in overall filament noise.

[Tom Phillips]

Bruce,
Do you ever read the other responses to the initial post?
Tom

[stokes]

I like to connect the CT for the heaters to the power tube cathode instead of ground,gets your heater ground above the the signal ground,helps keep the 50 or 60cycle hum out of the signal path.But earlier you described the hum as 100cycle,that can only be induced by the rectified ac.

[blodviol]

In the case of the Eur.AC when your 50hz AC is rectified it becomes 100hz,so it is very possible some increased filtering would help.But going to 20uf from 16uf wont make much difference,try 40uf.By the 2 leftmost 16uf caps,you are refering to the main supply ans screen supply,yes these are the ones to adjust,dont change the one going to your preamps.

Ok, I'll try that, but I wouldn't think it should be this noisy with the stock caps. Are there any wires i should make sure isn't touching any others? I've heard that could make noise. Or anything else i should think of?

Tríste

[stokes]

Check the caps to see if there is ac voltage at any of them.The main supply cap should have no more than 5vac,the rest should be no more than 1vac.