Tube Replacement Problem - Audio Research SP9 MKiii- V1 Tube Goes Dark w/ new V2 installed

Soundslike half the tube is working. They are balanced valve right? I think in one position, where they work and  are wired to the side that works. In the position where it stops or goes black, just the opposite.. One half is working one half is not... That seems logical. confirm it with a tester or a schemo, ay.. either or...

Regards

Thanks Don. 
If the amperex were dead then why would it be working well in my ARC LS1? It’s been in there a couple days now, glowing and sounding great. 
I did order a new set of tubes from Tube Depot for the SP9 mkiii and look forward to trying them this week. 

I have owned all the SP9s and currently use a MK3 in my home theater.

The Amperex tubes are a popular choice and should work great.

Sovtek tubes are junk IMO. They are reliable but sound very cold!

Most owners of the various SP9s threw out the stock ARC tubes right off the bat, and switched to NOS.

Even the best NOS tubes can go bad, and prematurely fail.

Sounds like you have a dead NOS tube. Buy a new set of NOS tubes. There are plenty available from reliable vendors.

tvad - OK, thanks!

@tvad Sorry, off topic. Tvad, I tried to reply to a dm you sent me and it says you're blocking me. I know that's an error, so just letting you know.

Hi TVad. Thank you. 
The Amperex always works. It’s the others that stop working when the Amperex is put into the mix. 
Then they all work fine under extended use in a separate tube preamp. Hence my bafflement. 

Quick Update @oldhvymec @tvad 

 I’ve cleaned everything and all tubes below work in a separate LS1 preamp as the sole tube. 

Here’s a summary-

SP9 preamp scenario 1- current state-  both sovteks work but I want an amperex in V2 location

SP9 scenario 2 - desired state-  V2 with amperex works, but sovtek in V1 goes dark, no phono

SP9 scenario 3- V1 w Amperex works and phono works, but Sovtek in V2 goes dark and line stages don’t work

SP9 scenario 4- Gold Lion 6922 in V2 works, and Sovtek in V1 works, all sound good from all outputs 

SP9 scenario 5- swapping the Gold Lion locations from scenario 4 and all works and sounds good

Scenario 6 - all individual tubes work fine during extended listening when used in a separate LS1 that has a single tube in the gain stage. As hoped the Amperex sounds best if only I could get it working in a pair in the SP9 :(

You plug your original valves in and everything works.

You plug in a NOS valve and it quits working.

You have a bad connection (I'd doubt) or a bad NOS valve (I suspect)

Nothing needs to be soldered. Nothing is broke.

It never hurts to clean the pins, socket pins and or tighten them if needed. That's not the problem.

Think about what you said.. One valve works one doesn't.

Regards

seems like roberjman is getting you there... surely a loose connection to tube pin in socket

Ha! Ok none of that. Thank you roberjerman. 

Don't yank them out of the sockets when power is on! You can wiggle them ok!

Is it safe to touch and pull the tubes while on? I see a couple voltage warnings :O :)

Thank you RJ for the suggestions. I’ve tried all 3 and no luck. Back to the originals and all is working as normal. :( I’m gonna have to have it checked out Bc I’m not a great solder guy. 

Possibility 2 is that the old V1 has an internal bad connection to its heater. That is the simplest fix! Just install a new tube with a working heater! Try the wiggle test! A bad internal heater connection can be intermittent also!

Try wiggling the dark V1 after installing V2. See if it lights! Cold solder joints can be intermittent! Tube sockets should not be soldered to pc boards! Poor connections can result!

Matching not needed! I suspect a poor solder connection on one or both of V1's socket's heater connectors to the pc board. That's why V1 won't light when you press the new V2 into its socket. Easily fixed - if you can get to the underside of that pc board and re-solder!