5F2 A slight signal????

[Jerome]

Building a 5F2A and every thing seems to be correct I thought at first it was a problem with my OT but switched it out and still nothing. I checked the 470 ohm resistor and it is a 460 ohm could this be a problem? I can only get a signal if i run a preamp threw it and blast it. My volume and tone do nothing. ?? Please help!!!!

[Ambugaton]

Most of your resistors will probably be 5% tolerance. Which means the actual value might be +5% or -5% of what is labeled.

You need to go through Doug's system of printing out the amps layout/schematic and slowly verifying each and every component value and placement.

Click on  "Before posting amp problems on new builds, read this." the permanent topic at the very top.

[Jerome]

Ive been through this and checked off every thing. Do the tone, volume, and input jacks have to be mounted on the chassis cause I have them mounted to a wooden suitcase?

[Ambugaton]

If your grounding is correct it shouldn't matter.

[Shack]

Jerome....its something simple, make sure all grounds are connected and look at all solder joints. Trust me, I go through this on every thing ive built and its always something simple

[Shack]

if you have an external speaker jack, make sure to use the right one, this got me twice 

[shooter]

Please help!!!!

once verify proper connections, ohm each R and verify the 1k isn't 100k, then do voltage checks on all the pins of all the tubes.

[PRR]

Input and output jack shells need to be grounded. On a metal box the box does that. In a suitcase you need wires.

[Joel]

I recently completed a 5F2A Tweed Princeton!  Glorious cleans with the volume at 1/4!  Tone Tubby 10" San Raphael speaker, home wound power and output transformers.

On my first full power up, plugged the guitar in - and nothing!  Recheck all voltages this time with the tubes in.  I'd forgotten to wire the first stage cathod resistor/capacitor to ground!  Quickly wired it up and got sound.  This is only my 7th build - so I'm still a rookie and allowed rookie mistakes right?

[Jerome]

I cant tell you how much I love this site and the people on it. You are all so patient and super helpful. Nothing but love for all of you. Thank you so much!!!!

[Jerome]

 Not sure if you can tell by the pics. I just dont get why this is not working. I have went forwards and backwards threw this thing. Maybe its just not suppose to go in luggage. The problem has to be in this upper area. If any one can spot my flaw by these pics it sure would be appreciated.

[HotBluePlates]

Let's start with a clear, close photo of the speaker jacks.  Cool?

[Jerome]

The white wire is the - feedback from the 22k resistor the green wire is my ground.

[shooter]

I can only get a signal if i run a preamp threw it and blast it.

are you jacking the "preamp" into the input jack, or splicing into the 6V6?

You have a meter and are very confident measuring HV?

If so;
Take a full set of voltage readings, anode, cathode, and grid.  Volts DC.

If NOT;
power OFF 5minutes, pull the AX7, ohm pins 3 & 8 (tube side) to ground.  Ohm pins 1 & 6 (tube side) to the PS side of the 100k resistors
 

[Jerome]

This is by far one of the worst designs I have ever come up with. I cant test the resistors or caps with out risking shock or disconnecting speaker, input, and tone, volume pots. Ive tested the tube sockets and every thing is firing correct.   I was more worried about how cool this would look than how it would function. :)

[Jerome]

I do have a question about the Volume pot shielded wire. It connects to pin 7 of the 12 Ax7 and the middle post of the Volume and shield to the 3 post and to ground. Do I connect the shielding and wire to the 12 Ax7 or strip back the shield  and just connect the center wire to the tube like on the input to pin 2????

[sluckey]

strip back the shield  and just connect the center wire to the tube like on the input to pin 2????

yes

[Jerome]

Found the problem! I have sound now but its not clean at all once i turn it past 1 it gets dirty and not louder. Really harsh tone not good!

[sluckey]

Congratulations. What was it?

[Jerome]

I had the 100k resistors switched with the 100 for the heater center tap. I did as they said and checked the between them and found it. Im getting to much gain. It brakes up to early. I love lots of clean head room. If I change the the 22k in the feedback loop will this give me more clean or do I even need this feedback at all? Its like I go from no volume to dirty. I have no bell like clean.

[sluckey]

Totally disconnect the 22K resistor. How does it sound now? If it sounds better then the NFB may be phased incorrectly. You will need to swap the OT primary leads to correct this.

[Jerome]

It sounds worse.  I will swap the OT leads and see how that sounds. Thank you so much!

[sluckey]

It sounds worse.  I will swap the OT leads and see how that sounds. Thank you so much!

Then you don't need to swap the OT primary leads.

[Jerome]

I listened to other 5F2 and they sound way better than this. I even used a Jensen 8in Alnico. Its just really harsh there is no clean. It breaks up at 2 even at 1 it sounds muddy. Should my rectifier tube be glowing red in the center?

[sluckey]

The only light inside the rectifier tube should be the glow of the filament.

You should measure the voltage on every pin of every tube and post them here. There could be a clue hidden in the voltage readings.

You should also keep tracing the circuit since your build layout is quite unorthodox. Plenty of places for wiring errors, poor solder connections, etc. to hide.

[Jerome]

Rectifier pin 4 and 6 read 6.7 V DC pin 2 and 8 nothing. Then with the rectifier back in and checking 6v6 on V AC pin 3 read 2.4 nothing on any of the other  pins. Then with the 6v6 in the 12 Ax7 pin 1 read 1.6 pin 6 also read 1.6. Nothing on the others.

[Jerome]

I also noticed I have a 460k in between my filter caps. I ordered a 470k but I got more 460 resistors. Could this be an issue?

[HotBluePlates]

Rectifier pin 4 and 6 read 6.7 V DC pin 2 and 8 nothing. Then with the rectifier back in and checking 6v6 on V AC pin 3 read 2.4 nothing on any of the other  pins. Then with the 6v6 in the 12 Ax7 pin 1 read 1.6 pin 6 also read 1.6. Nothing on the others.

You're checking for DC in places where AC matters, and checking for AC in places where DC matters.

[Jerome]

I tried both and it wasnt even reading I only wrote what would show up. Maybe my meter is messed up. I know it was,nt reading some of my resistors.

[shooter]

Maybe my meter is messed up.

new batteries then;
100 ohm
100k
120vac wall outlet
13.8vdc car battery
if they all read like you expect, your meter is cal'd

[PRR]

> 100k
> 120vac wall outlet

100k
CHANGE METER MODE off of Ohms TO VAC !!!! then...
120vac wall outlet

Meter on Ohms and poking wall outlets WILL mess it up. (Maybe not; mine peeps, but still not a Good Idea.)

[shooter]

CHANGE METER MODE off of Ohms TO VAC !!!! then...

I forget sometimes about variable skill-sets