EL84 "no-connection" pins

[Dr Tony Balls]

What are the forums thoughts on the EL84 pins that are not used? I've seen several diagrams that show pins 1, 6, and 8 and no connection. I've seen others that show 1 as no connection, but 6 and 8 as internal connection. Then i've also seen diagrams that show 1, 6, and 8 as internal connection. So what gives with that? I'm entertaining the use of empty pins for things like screen resistors and grid resistors, but is that asking for a problem with some tubes potentially having internal connections?

[sluckey]

It seems there has never been a "standardized" pin out for this tube. If you want to be safe then don't connect anything to pins 1, 6, or 8. Here's a pic of a 6BQ5 that clearly shows pin 1 internally connected (IC) to pin 2. I think I usually post this pic a couple times per year.

[bepone]

never use those pins, smoke will come out for sure, all tubes manufacturers are different on this matter

[R.G.]

+1
Never, ever trust a "NC" or "No Connection" pin on a device. The manufacturers feel free to do whatever they like on these pins. "No Connect" might mean "this doesn't connect to anything, so you can do what you want with it" or "DO NOT connect anything here".

It's only recently (maybe ten years) that IC makers have started marking not-otherwise-used pins as "do not connect", "connect to ground", "no internal connection", "may be left open", and so on.

[Dr Tony Balls]

Thanks for the input, everyone!

[2tone]

Older European tubes had pins 1 and 2 internally connected. But soviet and JJ tubes did not. So a Euro tube wouldnt work in an amp that wired the socket with pin 1 attached to a resistor. If pin 1 left bare then all EL84 tubes should work..

[CraigGa]

Does this apply to 6V6's too?
I used pin 6 to mount the grid resistor going to pin 5

Craig

[sluckey]

Does this apply to 6V6's too?

No. If you look at the bottom of a 6V6 you'll see there is no pin 6 on the tube base.

[CraigGa]

No. If you look at the bottom of a 6V6 you'll see there is no pin 6 on the tube base.

Thanks sluckey