First amp build, tweed deluxe 5e3, not working!

[Duelling Banjo]

Hey guys!

I think I already knew I would be making this post before I even ordered the 5e3 kit, and I'm sure this issue has been raised many times!

So I finished the build of my 5e3 from Modulus Amplification in the UK.

As a complete novice I did find certain aspects of the build quite challenging, so I don't doubt there may have been one or more mistakes made along the way, though hopefully not too many!

My observations on power-up are that all the tubes glow but there is no sound. Well, not entirely true, when I plug into one of the inputs and crank the volume to max there is a very faint growl from the speaker so the signal is (barely) getting through, but clearly something is going wrong along the way.

I'm wondering if anyone can provide advice or links to previous posts/websites where I can get a thorough and systematic testing procedure which will ultimately lead to diagnosing the problem(s).

Thanks in advance for your help, and let me know if there is any additional information I can provide.

 

[2L man]

First measure voltages and compare to various "5E3 voltage chart" you find searthing internet. This is easy troubleshoot task when fuse does not burn.

 

[Duelling Banjo]

Do I need a UK-specific chart for 240V mains supply or will it be the same after it comes out of the power transformer?

 

[2L man]

No. Secondary voltages are what interest us. Measure also anode and cathode resistor values if you did not write them to schematic when you did building. Resistances are used to calculate currents using voltage loss what come over resistors and they reveal lots of data of tube circuits.

 

[YellowBoots]

Please send us some clear photos of the build. We need to see everything from input jacks to circuit board to pots to tube sockets to power supply.

Here is a worksheet with circuit resistances you can check with no risk to you or the amp. If these turn out fine, then you will probably be asked to generate a chart of live voltages.

 

[Kev-wilson]

The guys on here know their stuff! Photo's of the board/wiring will help them.

Did you come across the RobRobinette's site? As as a first time builder myself found it ever so helpful!

 

[58Bassman]

When you made the connections to specific pins, did the sockets have numbers near them?

 

[FXBDM 1832]

One thing I do, and please correct me if it’s unsafe, is that while measuring voltages, volume up high, I will touch the grid pin of all triodes with my probe, starting at v2b and moving towards the input. If you hear a loud crackle, the problem is upstream of this point.

 

[King Fan]

One thing I do, and please correct me if it’s unsafe, is that while measuring voltages, volume up high, I will touch the grid pin of all triodes with my probe, starting at v2b and moving towards the input. If you hear a loud crackle, the problem is upstream of this point.

Good one. What I've heard called the 'pop' test. You can actually start from the grids of the output tubes, and they should get louder as you move toward the input -- more amplification between there and the speaker, right?

The amp-off resistance table from @andrewRneumann is priceless and safe -- do that while you're taking some beautiful clear pictures, overall amp, whole board, socket and pot shots, and clear close-ups of any hard-to-see bits.

Another safe amp-off test that's high-yield on a 5E3 tests the input jacks, resistors, and their complex wiring, courtesy of Dr. @D'tar . Plug in a guitar cable or plug; grid means pin 2 for normal and 7 for bright, of course.

 

[2L man]

My observations on power-up are that all the tubes glow but there is no sound. Well, not entirely true, when I plug into one of the inputs and crank the volume to max there is a very faint growl from the speaker so the signal is (barely) getting through, but clearly something is going wrong along the way.

I remember one build which output jack wiring made a short to OT secondary and only very quiet sound came out of loudspeaker. This can't be checked using resistance measuring without unsoldering at least one wire because OT secondary resistance is often less than 1 ohms so only looking that wires are connect right reveal it. Unsoldering one wire should show loudspeaker resistance on "correct" output socket lugs.

 

[Duelling Banjo]

Please send us some clear photos of the build. We need to see everything from input jacks to circuit board to pots to tube sockets to power supply.

Here is a worksheet with circuit resistances you can check with no risk to you or the amp. If these turn out fine, then you will probably be asked to generate a chart of live voltages.

View attachment 1088380

Herewith V1/V2, the rest to follow;

 

[Duelling Banjo]

Herewith V1/V2, the rest to follow;

View attachment 1088529

oops, I'll try again

 

[Duelling Banjo]

 

[YellowBoots]

V1 and V2 look good! I think all your values fall within the range of tolerance and nothing I'm seeing would keep the amp from making guitar noises. Carry on good sir!

Don't forget to check the resistance from B+1 to chassis. It should OL (infinite resistance). This is just a basic check for a short. I don't think you have a short because you haven't complained about heat, smoke, or blown fuses. Many problems would be caught before power-up if everyone just did this one check. "Amp builders in Ohio click here to learn this one neat trick!"

 

[Duelling Banjo]

V3/4/5 looks like some problems here!!

 

[YellowBoots]

V3/4/5 looks like some problems here!!

View attachment 1088549

Ok are you using some kind of grid stopper resistors for the power tubes? Like a resistor that you may have run from pin 7 to pin 5?

We need to see photos of those power tube sockets.

The V5 readings -- do you mean open circuit? Let's see where your PT is grounded. There should be a red and yellow wire (aka HT center tap) that is electrically connected to the chassis (possibly through a ground bus) somewhere. Please send a photo of that.

 

[Duelling Banjo]

Thanks Andy, I haven't grasped all the terminology yet so not sure what you mean by "open circuit" but I'll get the photos done so you can see for yourself.

 

[Duelling Banjo]

Ok are you using some kind of grid stopper resistors for the power tubes? Like a resistor that you may have run from pin 7 to pin 5?

We need to see photos of those power tube sockets.

The V5 readings -- do you mean open circuit? Let's see where your PT is grounded. There should be a red and yellow wire (aka HT center tap) that is electrically connected to the chassis (possibly through a ground bus) somewhere. Please send a photo of that.

I've got 1.5K resistors connecting pins 5 and 6, but no resistors connected to pin 7.

 

[YellowBoots]

I've got 1.5K resistors connecting pins 5 and 6, but no resistors connected to pin 7.

Ok perfect. Just go back and make sure you didn't accidentally skip pin 8 in your measurements. (IE, you measured pin 6 but thought you were on pin 7.)

 

[YellowBoots]

Thanks Andy, I haven't grasped all the terminology yet so not sure what you mean by "open circuit" but I'll get the photos done so you can see for yourself.

This is just a common problem of terminology. "no reading" is ambiguous because it might mean literally no reading was taken, or it might mean infinite resistance (like an open circuit), or some people might think no reading means 0 ohms, which is a short circuit (the opposite of a closed circuit). Add into the mix that ohmmeters have different ways of displaying an open circuit reading. What does yours say when you measure V5 pins 4 and 6?