5E3 - First build, first dud

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FrankTheReverbTank
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5E3 - First build, first dud

Post by FrankTheReverbTank »

So I built my first amp, a 5E3 and my guess is that it's not the best kit out there, but oh well. The light bulb limiter did not light up, the power light did. Tubes are glowing softly, adrenaline flowing wildly. Guitar plugged in, slowly turn up some knobs and...nothing. No crack, no hiss, no smoke (small victory), no sound (big loss).
I tripple checked my wiring, did a lot of googling, learned there are quite a few variations on the 5E3 theme, learned a few things about tube amps that I probably should have learned before I started this project, learned I still have lots to learn and on this board I found a wonderful chart with resistance values on various points.
I thought that would be a good place to start my troubleshooting journey. However...my measurements are so far off the chart that I quickly decided it's pointless because there must be a bigger problem than a loose contact or forgotten wire.
Also, although the chart says that readings may take a long time to settle but settle they will, mine don't settle before my multimeter goes into sleep mode. As an example of what I consider far off, the first reading (1st pin, 1st preamp to chassis) should read around 120K. Mine hovers from 3M to 10M before the meter goes to sleep.
So again I went over the whole thing, compared it to a Rob Robinette schematic, could more or less explane some minor differences, but nothing jumped out.
I'm kinda at a loss now on where to go from here, so I thought it would be wise to register an account and admit that I need help from wiser men.

Adding some pictures as I suspect that will be the first question.
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Last edited by FrankTheReverbTank on Sat Apr 05, 2025 9:18 pm, edited 1 time in total.
Helmholtz
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Re: 5E3 - First build, first dud

Post by Helmholtz »

Many of your turret connections don't look well soldered.
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martin manning
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Re: 5E3 - First build, first dud

Post by martin manning »

Get some voltages and post them. For starters, heater voltage (AC) across the pilot lamp, DC voltages on all the large power supply electrolytics, and the voltage at the un-grounded end of the cathode resistor/positive end of the cathode bypass capacitor. No sound often means there is a break or error in the signal path wiring.
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xtian
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Re: 5E3 - First build, first dud

Post by xtian »

+1, very iffy soldering. You're not applying nearly enough heat to the turrets to get the solder to wick to them.
FrankTheReverbTank wrote: Fri Apr 04, 2025 9:24 pmAs an example of what I concider far off, the first reading (1st pin, 1st preamp to chassis) should read around 120K.
No, this info is incorrect. Make sure you know how to measure for DC in the filter caps, and how to discharge them safely before continuing.
I build and repair tube amps. http://amps.monkeymatic.com
lonote
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Re: 5E3 - First build, first dud

Post by lonote »

Helmholtz wrote: Fri Apr 04, 2025 10:00 pm Many of your turret connections don't look well soldered.
Agreed, I noticed that as well.

Is your soldering iron heat adjustable? I might turn it up slightly & then use a little more solder & a little more time when applying heat to each joint, making sure it flows out.
maxkracht
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Re: 5E3 - First build, first dud

Post by maxkracht »

Yes, turrets take longer to heat up than you might expect. Use a blob of solder on your iron to bridge the gap between the iron tip and the turret to get better thermal conduction. Then once it gets hot enough, add a bit more solder for the extra flux to get things flowing and make your joint. The soldering iron tip, solder, turret, and everything else connected to the turret all need to get hot at the same time or it won't be soldered properly.

If you're really unlucky, some turrets are non-stick and just don't solder. I've come across this a couple times when trying to repair someone else's DIY amp made from a cheap chinese ebay turret board. I think antique electronic supply also had a bad run of turrets several years ago. Hopefully this isn't the case.
danman
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Re: 5E3 - First build, first dud

Post by danman »

Many of the solder joints do appear to be "cold" joints and the turrets could definitely use a bit more solder. A larger tip on your iron is also helpful when soldering to the turrets. The input and output jack wiring is a common area for mistakes in new builds so make sure that you check those areas fully for any wiring mistakes.

Is there a chance that you accidentally plugged the speaker into the extension jack and not the main jack? If you plugged into the extension jack by accident, the amp will be silent because the main jack must have a plug inserted for the amp to work properly.
Vince-
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Re: 5E3 - First build, first dud

Post by Vince- »

Hope some of this helps:
I use a weller soldering station at around 740 degrees. I use a chisel or screw driver shaped tip. I use a good solder. Kester or MG chemical 63/37 . I put a tiny bit of flux on each connection before soldering. It can also be helpful to pre tin the turrets etc. before assembly.
Tin the tip a little before each connection, heat the edge of the turret while placing the solder on the other side of the turret. So you're sure its heated all the way through. You'll see the solder race toward the heat.
At this temp it should heat quickly, a couple seconds . If you.find it isn't, you.may have an oxidized tip .
You'll want to see the solder fillet all the way around the turret where your lead wraps. You don't need a blob , as long as there is solder covering the lead you should be good.
Chopsticking around can help you find cold joints but it's probably a good idea to go over them all at this point.
Also to prevent overheating components you should use alligator clips as heat sinks on the leads til you get used to soldering quickly.
Also it's quite easy to.miss some simple connection here or there in a build which can account for no sound.. ( ask me how I know lol)
Don't get discouraged.
The build looks tidy , overall, you'll get there.
jabguit
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Re: 5E3 - First build, first dud

Post by jabguit »

Are you plugging the speaker in the non-switched output jack? If so, there may be your problem.

cheers,
Jack Briggs
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Stevem
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Re: 5E3 - First build, first dud

Post by Stevem »

Many poor solder connections everywhere as many have posted about.

I keep my iron a 680 degrees and fitted with a tip of good mass, but not so big to make it difficult to maneuver around.

A 40 watt non adjustable iron will not cut it in general, and especially if your soldering up the ground terminals of input or speaker output jacks with them bolted to the chassis already.
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Phil_S
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Re: 5E3 - First build, first dud

Post by Phil_S »

You've done well so far, but that amp isn't finished. I suggest the others who posted are really cheering you on to get to the finish line. As other said, more solder is needed. Go for it!
FrankTheReverbTank
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Re: 5E3 - First build, first dud

Post by FrankTheReverbTank »

Thanks for the many replies so far. Let me respond to all of the above in one post.

Soldering has proven somewhat of a challenge. I'm used to soldering PCB's, but this was a totally different ball game. In my PCB world I rarely go over 300 degrees. I cranked my iron up to 400 for this project, which I thought was really high. I now learn that 700 makes a good starting point. I'll give that a shot. [On edit: I'm from Europe. Are we talking F or C?]
Also, I used lead free solder for the first time and I bought a new midrange welding station for the workplace I set up in the basement specially for this project. I've been cursing both of them many times but I refused to get my Weber and the 60/40 from my 'lab'.
Having said all that, I did do point to point measurements off the turrets before placing the board and these all checked out.

The speaker was plugged into the correct jack. One thing I thought was odd is that a continuity test beeped a 'short' between tip and ring. After checking the connections many many times I drew the conclusion that the two must somehow connect through the output transformer. Also (and this might be totally unrelated), I measured the resistance of the speaker. I thought this would simply show 8-ish Ohms, but I can't get a stable reading and what I do read is way below 8. Is that normal or at least explainable? I'm using a brand new Jensen C12N (8 Ohm).

For now I'll start with resoldering the turrets and then do the suggested V readings:
- Heater across the pilot (AC)
- Power caps (3x)
- Cathode bypass (2x)

Will be a few days before I'll get around to it.
Last edited by FrankTheReverbTank on Sat Apr 05, 2025 7:02 pm, edited 1 time in total.
maxkracht
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Re: 5E3 - First build, first dud

Post by maxkracht »

8 ohm speaker usually measures around 6 ohms resistance, the 8 ohms is impedance, which you would need a different meter to measure.

You should be measuring dc voltages at each tube socket pin. Black lead clipped to ground, only use one hand with the red lead and other hand in your pocket while the amp is on to take measurements to minimize shock risk.
AC voltages you would measure across the red wires, yellow wires, and green wires, not to ground.
Yoda
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Re: 5E3 - First build, first dud

Post by Yoda »

FrankTheReverbTank wrote: Sat Apr 05, 2025 5:50 pm Thanks for the many replies so far. Let me respond to all of the above in one post.

Soldering has proven somewhat of a challenge. I'm used to soldering PCB's, but this was a totally different ball game. In my PCB world I rarely go over 300 degrees. I cranked my iron up to 400 for this project, which I thought was really high. I now learn that 700 makes a good starting point. I'll give that a shot. [On edit: I'm from Europe. Are we talking F or C?]
Also, I used lead free solder for the first time and I bought a new midrange welding station for the workplace I set up in the basement specially for this project. I've been cursing both of them many times but I refused to get my Weber and the 60/40 from my 'lab'.
Having said all that, I did do point to point measurements off the turrets before placing the board and these all checked out.

The speaker was plugged into the correct jack. One thing I thought was odd is that a continuity test beeped a 'short' between tip and ring. After checking the connections many many times I drew the conclusion that the two must somehow connect through the output transformer. Also (and this might be totally unrelated), I measured the resistance of the speaker. I thought this would simply show 8-ish Ohms, but I can't get a stable reading and what I do read is way below 8. Is that normal or at least explainable? I'm using a brand new Jensen C12N (8 Ohm).

For now I'll start with resoldering the turrets and then do the suggested V readings:
- Heater across the pilot (AC)
- Power caps (3x)
- Cathode bypass (2x)

Will be a few days before I'll get around to it.


I have to say that my soldering game improved a hundred fold once I stopped petering around with that lead-free nonsense and started using real leaded solder, only Kester 63/37 for me.
wpaulvogel
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Re: 5E3 - First build, first dud

Post by wpaulvogel »

The amp will never be right with lead free solder. A 5E3 was built with 60/40 or 63/37. Get real solder. 700F.
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