First 18w build - EF86 Lite 2P

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Re: First 18w build - EF86 Lite 2P

Post by Bieworm »

yello wrote:
Tue 04/26/22 3:17 pm
JMPGuitars wrote:
Tue 04/26/22 11:39 am
Take a look at my photo for better ways to hand the wiring and transformers. Disconnect your impedance switch and twist the OT wires. Mine are twisted and heatshrinked in the photo.
I think I remember being told only A/C wires need to be twisted, but I can do the OT wires to the speaker, and the primary side too if needed.

Other than that, and your use of heatshrink on everything (why heatshrink every solder connection?), what else is there?
I know the answer..
If you build your stuff with half the OCD Josh has.. you also get half the fine look of the builds. That's the case with me I think..😉
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Re: First 18w build - EF86 Lite 2P

Post by yello »

Bieworm wrote:
Tue 04/26/22 3:56 pm
I know the answer..
If you build your stuff with half the OCD Josh has.. you also get half the fine look of the builds. That's the case with me I think..😉
So is it mainly aesthetics? I am much higher on function over form, especially on something unseen, though I certainly want everything to overall look clean and to be done according to safety and performance specifications.
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Re: First 18w build - EF86 Lite 2P

Post by JMPGuitars »

Audio signal is AC. Some of the heat shrink is overkill, but when you see wires held together in my builds with heat shrink, it's to help limit vibrations or wire movement. Covering solder joints isn't necessary, and while it does look cool, it can also help prevent oxidation.
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Re: First 18w build - EF86 Lite 2P

Post by yello »

JMPGuitars wrote:
Tue 04/26/22 4:39 pm
Audio signal is AC.
I was just thinking about the power connections - and missed that obvious point!
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Re: First 18w build - EF86 Lite 2P

Post by yello »

Here are some updated photos, just finished wiring it up (short of my pilot light which I can't find so need to reorder one). I've tinkered with vintage amps before, but this is my first complete amp build, totally fun!

Now I need to figure out where to heck to buy some quality new tubes (everyone is out of stock) or I suppose I can use some vintage ones I have on hand if needed, but they are untested.

Then I gotta figure out how to do my first testing/start-up. I imagine this is the place to start ->

https://robrobinette.com/Tube_Amp_Startup.htm

And the pictures:

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Re: First 18w build - EF86 Lite 2P

Post by JMPGuitars »

Can you post some high quality close ups of your turret board soldering? It's hard to see from the photos.

Also, you forgot to twist the rectifier heater wires.
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Re: First 18w build - EF86 Lite 2P

Post by yello »

JMPGuitars wrote:
Wed 05/04/22 11:27 am
Can you post some high quality close ups of your turret board soldering? It's hard to see from the photos.

Also, you forgot to twist the rectifier heater wires.
Wires now twisted....thanks for the catch. Anything else of note? I figured I would chopstick wire placement if needed after startup.

Image

Here are soldering pics from turret board. I read the soldering technique tips and watched the videos though I'm sure I have a long way to go on my technique:

Image

Image

Image

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Image
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Re: First 18w build - EF86 Lite 2P

Post by JMPGuitars »

You need to work on your turret soldering. If your soldering iron is adjustable, turn up the heat a little bit. If it's not adjustable, get a better iron. Use a bit of solder as a "heat bridge" and when that solder moves to the turret on its own, add more solder...to the opposite side of the turret. The solder should melt when touching the turret, you shouldn't need to touch the iron with the solder.

Review turret soldering in the videos linked in my signature. Most of your turret solder joints don't have enough solder. You don't want too much either, but review the videos and try a few after.

Thanks,
Josh
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Re: First 18w build - EF86 Lite 2P

Post by yello »

JMPGuitars wrote:
Wed 05/04/22 1:05 pm
You need to work on your turret soldering. If your soldering iron is adjustable, turn up the heat a little bit. If it's not adjustable, get a better iron. Use a bit of solder as a "heat bridge" and when that solder moves to the turret on its own, add more solder...to the opposite side of the turret. The solder should melt when touching the turret, you shouldn't need to touch the iron with the solder.

Review turret soldering in the videos linked in my signature. Most of your turret solder joints don't have enough solder. You don't want too much either, but review the videos and try a few after.
I have an adjustable soldering iron, a Weller WLC100, typically turned up to 3.75 to 4.

I am using the exact technique as you describe, though it sounds like if I don't have enough solder I might be stopping solder flow too early. I was trying to avoid having too much.

I'll turn my iron up a bit - is it best to remove current solder and start over, or just add more solder? I'll use a magnifying glass to aid my inspection to get them right.
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Re: First 18w build - EF86 Lite 2P

Post by JMPGuitars »

yello wrote:
Wed 05/04/22 1:17 pm
Is it best to remove current solder and start over, or just add more solder?
Sounds like you erred on the side of being too cautious. Remember, you want the concave solder joints, but if they're too shallow to have the sexy curves, there's not enough solder.

If you heat the turrets up well enough, and you mix the fresh solder in well, you're probably fine. Reflowing solder is common, and it's not like you're trying to replace really old solder joints without cleaning them first. Be very careful not to nick anything with the iron, especially around those big caps.

That Weller iron is okay, but it's much better if you have an iron with a temperature display (and preferably can be calibrated). On the other hand, you could get something like this to test your actual temperature: https://www.amazon.com/Digital-Solderin ... 07WTLK2RT/

I have one of those generic thermometers, but not from the same link.

Thanks,
Josh
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Re: First 18w build - EF86 Lite 2P

Post by JMPGuitars »

Some of the turrets are fine, just clean up and add to the ones that look thirsty.
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Re: First 18w build - EF86 Lite 2P

Post by yello »

JMPGuitars wrote:
Wed 05/04/22 1:40 pm
Some of the turrets are fine, just clean up and add to the ones that look thirsty.
I had originally thought they looked pretty good - but now that I have added solder I can see the difference, much better now.
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Re: First 18w build - EF86 Lite 2P

Post by yello »

Just did the highlighter check of my schematic versus my amp, wire by wire, part by part. I had confidently assumed I wouldn't find mistakes as I was methodical with everything...

...but, I see why its a good exercise, and saves frustration later, I found a mistake! I didn't connect the heater wire at pin 5 of v2, only had it going to pin 4.

Everything else looked fine, short of I still need to order my pilot light and install it. I'll be using a 120v amber light.

Image

Next I need to read through start-up procedures: https://robrobinette.com/Tube_Amp_Startup.htm

And I think I have some vintage tubes I can pop in - I wanted to try reissue Mullards but I can't find them in stock.
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Re: First 18w build - EF86 Lite 2P

Post by yello »

Fixed the lone mistake I located in my highlighter test, added a jumper between pins 4 & 5 on the v2 12ax7.

Here are the two tubes set I found in my stash that might work:

1) New set of JJ ez81, el844's, 12ax7, and vintage Mullard ef86.

OR

2) Vintage Rogers ez81, vintage Baldwin organ el84's, NOS GE 12ax7, and an Amperex ef86.

Either ef86 could work with either setup.

I'm leaning towards the JJ's at first as they are new and in theory will function (in a bid to eliminate a tube problem being confused for an amp problem) then would switch to using the vintage tubes to play the amp. (Josh read my mind while I was editing my post to say the above).

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Last edited by yello on Wed 05/11/22 1:30 pm, edited 4 times in total.
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Re: First 18w build - EF86 Lite 2P

Post by JMPGuitars »

lol, close. Throw the JJs in to test. Once the amp is tested and you know it's all good, put in the better tubes.
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Re: First 18w build - EF86 Lite 2P

Post by yello »

Initial amp startup questions (gleaned from reading these start-up procedures):

https://robrobinette.com/Tube_Amp_Startup.htm:

1) Do I need to form new caps slowly with a variac (robinette says it isn't necessary but is helpful)?
2) As I understand it, no speaker load needed until the point of putting in power tubes, correct?
3) Should voltage reading for the circuit be taken with a light bulb limiter and/or variac in place?

If answer to 1 and 3 is no, then I assume I use my limiter at first to ensure no shorts, then move on to full power and test/measure appropriately from there.
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Re: First 18w build - EF86 Lite 2P

Post by Bieworm »

yello wrote:
Wed 05/11/22 3:37 pm
Initial amp startup questions (gleaned from reading these start-up procedures):

https://robrobinette.com/Tube_Amp_Startup.htm:

1) Do I need to form new caps slowly with a variac (robinette says it isn't necessary but is helpful)?
2) As I understand it, no speaker load needed until the point of putting in power tubes, correct?
3) Should voltage reading for the circuit be taken with a light bulb limiter and/or variac in place?

If answer to 1 and 3 is no, then I assume I use my limiter at first to ensure no shorts, then move on to full power and test/measure appropriately from there.
It's best to use the lightbulb current limiter for initial start up. The variac is not really required but since you have one.. why not?
Measure voltages of the B+ nodes with the light bulb installed. The voltages should be lower than specced, and this gives you an indication that everything is on par.
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Re: First 18w build - EF86 Lite 2P

Post by yello »

Bieworm wrote:
Thu 05/12/22 2:12 am
It's best to use the lightbulb current limiter for initial start up. The variac is not really required but since you have one.. why not?
Allright, found time to begin initial startup - all is well with limiter, no shorts.

I used my Variac (after completely reworking the Variac wiring and plugs) to slowly form the caps last night.

Tonight I will finish testing and measuring with tubes and then load, and then guitar. Fingers crossed!

My 120v pilot light just arrived in the mail this afternoon. How do I wire it, one wire to neutral (on IEC or transformer?) and one wire connected to hot (either at the switch or fuse or transformer?)?
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Re: First 18w build - EF86 Lite 2P

Post by yello »

Took first stab at voltages with light bulb limiter in place, with a 29w bulb:

Image

I imagine next step is to remove the limiter and take voltages again?
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Re: First 18w build - EF86 Lite 2P

Post by yello »

And here are the voltages without the limiter:

Image
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