I got the Loose Tube Blues

[efhjr]

I'm having a problem with my Wright Sound WPL10V preamp. One of the tube sockets -- the one that controls the right channel of the phono stage -- seems to be misbehaving and I don't get any sound out of that channel.

I can jiggle the tube with my finger and get the sound to come out. But when I pull my finger away, the sound goes away. I figure there's a problem either with the tube pins contacting the socket, or something under the socket.

I've rolled several tubes in that socket and the problem remains. I'd love to hear some ideas of how I can correct this.

[Metralla]

"I have detailed files"

Rolling tubes will cause the contacts to weaken their grip. You need to tighten the individual little sockets that the pins go into. A jewelers screwdriver is perfectly suited to the task at hand.

I have those expensive Yamamoto Teflon sockets with silver-plated phosphor bronze contacts ("fingers") and they can be a problem, because the Teflon gives a little over time and the grip on the pins loosens. In some respects, the little fingers that make contact with the pins are fragile, and I did not want to bend them too much.

Here is my technique.

I rummaged through my drill bits and used my vernier calipers to find a bit that was just a tad smaller than the tube pins. I used this as a guide (after cleaning it with pure alcohol), and carefully bent the fingers with the jewelers screwdriver until the bit was a nice snug fit. This enabled me to attend to each contact in turn without inserting the valve.

I also took the opportunity to clean the contacts with Caig DeOxit and a small pipe cleaner brush. Swabbed it out with a pipe cleaner. Cleaned the pins with DeOxit and added a dab of high temperature Caig ProGold GxL.

Insert tube. Perfect!

Regards,
Geoff

[Steve Hoffman]

Unplug the little bugger and let the power discharge OVERNIGHT before doing ANYTHING to it, ok?