First Build troubles - 5E3 w/ Voltages & pics!!!

[Wittgenstein]

Re-wired all the input jacks with new switchcraft jacks and still no sound. I measured the B+ voltages with the standby off (amp should be making sound) as it runs through the circuit. The first 16uf where the main DC comes into the board measured 421V, the second 16uf to the right was 383V, and the third 16uf measured 300V. Then further to the right where it runs to the resistors (100K & 56K, 100K & 100K) in parallel to each tube it also measured 300V on both. Do you have any suggestions on what to check next. I'm running out of ideas.

I can tell the 5y3 is working, supplying power down the line, so I'm sure the power switch, fuse, standby and power transformer solders are fine. I also measured the filament pins while running and I know these are good as well (and I can see the tube glowing). I would assume it is somewhere in the pre-amp, PI, or EQ stage that something is awry, but I have ohmed out every pin through the board and it all jives. The only thing that I cannot really check is the capacitors. I know a DMM is not much help here besides showing shorts. The large 16uf caps showed around 9ohms of resistance that continue to grow, which is normal. Could I have fried my OT, is there a way to tell? I'm just not sure what to try anymore.

I do not have any extra 6v6 or 5y3 tubes, so I plan on purchasing some just to eliminate any doubts of bad tubes.

[tubeswell]

... the third 16uf measured 300V. Then further to the right where it runs to the resistors (100K & 56K, 100K & 100K) in parallel to each tube it also measured 300V on both. Do you have any suggestions on what to check next. I'm running out of ideas.

Seeing as how the plate resistors in the pre-amp are measuring the same as the HT voltage, that shows that the pre-amp tubes are not conducting, because if they were, you would see the plates sitting at about 1/2 to 2/3 of the HT voltage at that point. So...:

1) double-check the wiring from the cathode pins (pins 3 and 8 respectively) of each of the pre-amp tube sockets to the cathode resistors and thence to the ground return paths for those cathode resistors; and

2) check the wiring from the plate socket pins (1 and 6 respectively) of the pre-amp sockets to the relevant plate resistors, and thence from the other side of the plate resistors to the HT supply at the +ve side of the pre-amp filter cap

[Wittgenstein]

Attempt #3 - Hoffman Style Layout

Update: Unhappy with my first soldering attempt and subseqent fixes, I decided to redo the circuit board in the Hoffman style. Last night I finished wiring up and installing my newly fabricated board, but I did not have much time to mess around with it.

It is not working properly however. I'm thinking I have a bad solder somewhere in the pots. When I turn it on, I have to crank the volume up to 10 or 11 to hear a very faint guitar sound coming from the speaker. Even though it is very quite, it sounds distorted, but this might be from having the volume all the way up. When I changed the channel the guitar was plugged into, it did the same with the other volume knob. On the plus side, I do not hear any 60 or 120 cycle hum when powered on, like I did before. Now I just have to trace down the problem. Hopefully I can get it running tonight.I will be adding pictures of my work tonight as well as post all the voltages. I ran throught everything last night briefly, and at least the B+ line looked in order.

[tubeswell]

With the amp on, carefully do the pop-test (by touching a test probe - like your V meter probe) at each stage's grid (nearest convenient connection on the board) starting with the output tubes and working backwards. You should get a quieter pop at the 6V6 grids and successively louder pops at the cathodyne, cathodyne driver, and lastly the V1 grids. If you don't get a good pop, that is the stage to look at.

[Wittgenstein]

With the amp on, carefully do the pop-test (by touching a test probe - like your V meter probe) at each stage's grid (nearest convenient connection on the board) starting with the output tubes and working backwards. You should get a quieter pop at the 6V6 grids and successively louder pops at the cathodyne, cathodyne driver, and lastly the V1 grids. If you don't get a good pop, that is the stage to look at.

Great advise as usuall, thank you. I tested that as well last night and from what I could tell, it did not pop on any of the grids. It is normally a loud pop, especially on V1. It did however make the popping noise when I probed the tone and volume pot lugs, which is what lead me to believe it is a bad connection there.

I am really happy with how the board turned out. I was able to place the turrets in better locations for my tight chassis, and the ground buss is a HUGE improvement over the Triode or Fender grounding schemes. My soldering skills have improved even more, this being the fourth time I have assembled this amp... lol. I also used shielded cable for the inputs to V1 as well as the the sesitive grid (pin 2 of the 12ax7) wire running to the pot lugs (the suspect area).

[tubeswell]

Yeah it pays to have a good pot-soldering technique. If you get too much solder on the pot lugs or if you are soldering the pots with the lugs 'up', excess solder can run down the hot lug and into the pot and stuff the pot up for good. Or if the lugs come loose from the phenolic with too much mechanical stress, that can stuff the pot up as well (if that is the problem - but reading the unconnected pot with your R meter should tell you if any of the connections are dead). Or if you somehow manage to ruin the phenolic and or resistive trace inside the pot with excessive heat or solder, that can cause voltage leakages. No remedy for that except a new pot.

[Wittgenstein]

Hoffman Style Board Pics

My Triode 5E3 kit came with the red turret board that is very similar to the original Fender layout. That was one of the biggest reasons I selected this kit originally. Now I have all the parts to make my own boards, so I figured I try out the Hoffman style layout this time. I am really happy with how it turned out. Here are some pics of it pre-solder.

[Wittgenstein]

Attempt #3 - It's Alive

I was excited to get home last night and troubleshoot this amp. It was making sound, but very quietly and only if the volume was cranked up. So I decided to plug my speaker into the 16 ohm tap (just for a moment at low volume because I do not want to damage the OT) and it works, sounds perfect. This lead me to believe it had to be the secondary 8Ohm tap from the OT that had a bad connection. When I got it up on the bench under a light, I noticed that when I had tightened down the main 8 ohm output jack nut, it had spun the lugs enough to break the wire. It was not mechanically connected but rather just touching enough to pass a weak signal.

So long story short.... I soldered the 8 ohm secondary back up and it works. It does seem that the shorting jacks are not working properly however. When I touch the chassis it becomes almost silent, otherwise it sounds like a open cable plugged in. I will have to mess around with it some more tonight when I have a chance. I will also post my voltages (running a bit hot like before, but the 470ohm 2Watt resistors seem to help out a bit). Below are some gut shots of what I hope is the last time of wiring up this chassis. I think it is the cleanest wiring/soldering job I have done yet!

Any critiques or suggestions on the build would be greatly appreciated.

[cminor9]

not bad man. Just two things:

The soldering gets better. My first build was a little sloppy on the solder, but as you go on you learn to use less solder and more heat. I also find that using turrets, for me at least, causes me to be neater because you can make very solid mechanical connections by wrapping leads around the turrets. Then you just need a little bit of solder to hold it all in place. If you get the leads and the turret hot enough, the solder flows and fills in all the voids. Just make sure you use an alligator clip as a heatsink on the leads of heat-sensitive components (caps, diodes).

Are you getting any hum? It looks like your heaters are pretty close to the leads to the tubes. If you aren't getting any heater noise then no worries. If you are, try tucking those up against the outer lip of the chassis, away from the other wires. That might help cut some noise.

[ThermionicScott]

I'm a little late to the party, but are you using one of those Mercury Magnetics power transformers with the 380-0-380 secondary?

- Scott

[Wittgenstein]

I'm a little late to the party, but are you using one of those Mercury Magnetics power transformers with the 380-0-380 secondary?
- Scott

I used the transformers that came with the Triode 5e3 kit, with the exception of the output transformer. Back when I ordered the kit, Triode offered the TF-110-4816-UL as an replacement option. I know it is larger than the original tranny that Fender uses, but it had 4,8, & 16 Ohm out which I wanted for more speaker options, seeing as it will be a head and not a combo.

Power Transformer - 40-18021
120V Primaries: Secondaries: 710V 100ma DC: 6.3V @ 1.65A : 5V @ 2A

Output Transformer - TF-110-4816-UL transformer w/ paper bobbin
Primary 6600 ohm CT with screen taps at 43% Secondary 0-4-8-16 ohms
Response flat within 1 dB 50 Hz-20KHz at 20 watts

[ThermionicScott]

I used the transformers that came with the Triode 5e3 kit, with the exception of the output transformer. Back when I ordered the kit, Triode offered the TF-110-4816-UL as an replacement option. I know it is larger than the original tranny that Fender uses, but it had 4,8, & 16 Ohm out which I wanted for more speaker options, seeing as it will be a head and not a combo.

Power Transformer - 40-18021
120V Primaries: Secondaries: 710V 100ma DC: 6.3V @ 1.65A : 5V @ 2A

Output Transformer - TF-110-4816-UL transformer w/ paper bobbin
Primary 6600 ohm CT with screen taps at 43% Secondary 0-4-8-16 ohms
Response flat within 1 dB 50 Hz-20KHz at 20 watts

That PT has good specs for a 5E3. (The OT is more appropriate for a blackface/silverface Deluxe, but it'll be fine.)

I spotted a Sovtek "5Y3" in one of your pictures -- that's partly why your B+ is so high. The good news is that your JJ 6V6's can take above-normal voltage and dissipation without trouble, so it's up to you whether it's worth fixing.

- Scott

[Wittgenstein]

That PT has good specs for a 5E3. (The OT is more appropriate for a blackface/silverface Deluxe, but it'll be fine.)
I spotted a Sovtek "5Y3" in one of your pictures -- that's partly why your B+ is so high. The good news is that your JJ 6V6's can take above-normal voltage and dissipation without trouble, so it's up to you whether it's worth fixing.
- Scott

I just received my first RCA NOS 5Y3GT, bought on ebay, in the mail today, and I have 3 more on the way. One is a GE NOS that tested 100% good. I was able to get all 4 for about $24 shipped. I plan on swapping it out tonight or this weekend and taking new voltage measurements.

Edit: I will do the same for my 5f1 champ, which currently is running a Sovtek 5y3 as well. I think it sounds amazing as it is now, so I will have to see.

[wyatt]

I just received my first RCA NOS 5Y3GT, bought on ebay, in the mail today, and I have 3 more on the way. One is a GE NOS that tested 100% good. I was able to get all 4 for about $24 shipped. I plan on swapping it out tonight or this weekend and taking new voltage measurements.

Edit: I will do the same for my 5f1 champ, which currently is running a Sovtek 5y3 as well. I think it sounds amazing as it is now, so I will have to see.

One NOS RCA will probably last you a lifetime in each amp, unless you are a heavy gigger.

[loupy31]

Hi Every one,
My Name is Peter, this is my first post on this forum , I have just finnished building 5E3, and I'm also having problem voltage readings.
But I will work on them, For now I was woundering, how do I measure the tube bias for the 6V6gt's , not sure how to do this, I think I might have the tubes rather on the warm side, but need to find out.

Peter