tube failure

[Paul Birkeland]

Apply your iron to the tip of each fat pin and hold it there for a while with the tube upside-down.  Eventually, you'll see the solder start moving inside the tube pin, and you can feed a little extra through the hole in the tip of each of those pins.  Do not add any solder to the outer portion of the tube pins where they slide into the socket.

I've attached a picture of what a 4 pin base looks like before it's installed on a tube.  You can see that the ends of the pins are hollow and that's where the solder goes in.  The EH bases aren't all the way hollow on the ends, but there's still a hole where solder can be fed in.  For the tube in question, it's possible that one of the filament leads wasn't perfectly soldered and it has just moved away from touching whatever was allowing it to conduct. 

[lesouthern]

I have added solder to the tops of the large pins of the offending tube twice now, installed the tube, and am getting the same erroneous voltage readings I list above in this post. The resistance of the offending tube remains the same, about 1.2au. Wonder if I'm doing something wrong, or if something else is causing this failure.

1.  This is my soldering iron->
https://www.amazon.com/gp/product/B07RZV2DW8
I'm turning up this to 8- the highest it will go.
Is that hot enough to do the work you are advising me to do?
If so, how long should I have the tip on the pin for this to work?
Is it just the tip of the pin I should be heating, or other parts of the pin?
And just the large pins I need to do this on, not the small ones?
I'm noticing once the iron is hot it takes about a minute for the top solder to melt.

2. Given the erroneous readings of 0V on the terminals I listed above, could this be any other issue other than the tube one you are advising me?

3. I have three other Bottlehead projects- Crack, Reduction, and Moreplay. As far as I know, the tubes on these are fine. Are the 2A3 tubes more susceptible to have this happen?

[Paul Birkeland]

I suspect you will need to have the tip held against the base pins for 1-2 minutes to get the solder to flow out as desired.

I have never run into this issue on any tubes other than new production 2A3 and 300Bs.

[lesouthern]

After about five tries the big pins on my bad tube stopped accepting additional solder

I have plugged the tubes in, and am getting a small glow from the sides of the bad tube, but the top is still not glowing. It is getting slightly warm, but not hot like the good one

In comparing the bad tube to the good one, note that the solder in the small pins is recessed. Do I need to add solder to the small pins here as well?

[Paul Birkeland]

At the end of they day it's certainly possible you got a short lived dud of a tube, and just buying a replacement for that one tube would be the best way to go.  Though I would expect most new 2A3s to last 5-10 years, there will be a few here and there that die early. 

[lesouthern]

Ok- I'd like to avoid buying another dud, as you know these aren't cheap.

With tubes- do you get what you pay for? Are there more reliable 2A3 I can get? Not looking for anything fancy.

Do you have a recommended vendor or site?

[Paul Birkeland]

Doc B. and Eileen can speak to the number of tube failures we experience early in life from New Sensor production, but in general I would expect it to be well under 1%.  Yes, you can buy a pair of EML 2A3s for $700+ and they will offer you a nice warranty, or you can buy a quad of Psvane 2A3s off eBay for $250 and have some spares that you're unlikely to need.  The EH 2A3s have shot up so much in price that the one you have could probably sell for $100+ on its own as a good used tube to offset the cost of whatever you decide to do.

[Doc B.]

Yes, the Sovtek 2A3s from New Sensor are generally quite reliable. That is always a major consideration when we choose a tube.

[Deluk]

Is it possible that you have somewhere locally that can test both of your valves? Guitar shop?