On 10/15/2023 10:27 PM, Jay Hennigan via Jukebox-list wrote:
On 10/15/23 17:49, Tony Miklos via Jukebox-list wrote:
I'll check that out tomorrow and report back. Whatever did go wrong, it did have B+ voltage from it to ground (but zero from the other 6L6 to ground). I always wondered how they got metal cases to seal good enough, I didn't know they were glass inside! Now you have me thinking, if the keyed pin in the center was off, and the tube was turned a few notches, that would make sense for it to have B+ on the case.
Definitely inspect the socket. Pin 1 should be either left floating or preferably tied to ground. If it's used as a tie point there's no problem with glass 6L6s but it will be connected to the case if a metal tube is used.
OK, I did have the pin numbers mixed up when checking for a short with a meter. But the tube was in the socket correctly. This morning it made the noise (turned the wattage down to 1 so it didn't blow a speaker). I tried only the suspect 6L6 without the other one in and it acted up. So I swapped the tube to the other 6L6 socket and had my hand on it so I could yank it out if it acted up. It did act up big time, and with each crackle I got one heck of a shock until I got my hand off of it. I had tested the tube before, but tested it again and if checking the emission for 20 seconds to really warm it up, it did show shorts, but with this tester I don't know where the short is. Also when hot it starts to show grid leakage and it keeps going higher as I keep running the test. The socket #1 pins are not grounded, maybe luckily or it may have fried a transformer. I won't bother grounding them since I'm installing 2 matched glass ones. By the way, none of this happened while it was on the bench.
Thanks for your insight on metal tubes! Now to test it more. It normally acted up as it was warming up so it will get a lot of on/off cycles to test.