Tube changing procedure/suggestions

[cesjr]

I'll soon be replacing the power tubes on my Mark IV (the first time I've done a tube replacement.) My question is, should I just swap out preamp tubes as they start to show signs or noise and microphonics? Or is it better to replace all the preamp tubes on a regular basis like the power tubes?

Also, where can I find online instructions for changing tubes?

Thanks

 

[Boogieman]

I don't have a habit of replacing preamp tubes periodically. If I suspect there is a problem with a preamp tube, I would tap the preamp tubes one by one gently, with a wooden pencil or wooden chopstick while the amp is on (the other hand behind my back, just in case). The tube on the V1 socket is usually very sensitive to microphonic tubes, so that would be the place to start.

I don't know if there is any online instructions on how to change tubes, but I think common sense would do it:

1. Make sure the amp is off, and that the power cord is unplugged from the AC outlet

2. Don't know if this helps, but I do it anyway: with the power cord unplugged from the AC outlet, flick the Power and Standby swtiches on once and then turn them off.

3. Make sure the tubes are cool enough too be handled. I don't like to touch them when they are hot, even though I seldom touch a tube with barehands.

4. Never pull a tube out of its socket by yanking it with force. Gently hold the spring clamps down and gently wiggle the tube out of its socket. The same for putting a new one in.

I have heard some people use contact treatment such as Caig Labs Pro Gold for power tube pins. While I don't use it, I suppose it doesn't hurt. Just as well, check the tube sockets for signs of arching.

 

[Brewski]

Here's just a quick instruction from Eurotubes...

https://ssl.eurotubes.com/euro-i.htm

 

[cesjr]

Thanks for the informantion guys. My preamp tubes all seem good. They're going on 2 years old, they're just getting broken in. :lol: But I know it's long over due to replace my power tubes.

It's seems like most people simply replace the preamp tubes as they go bad. Meaning, why replace all of them if only one is bad. Anyway, that answers all my questions, thanks.

cesjr

 

[Russ]

Just remember that driving your front end hard (heavy gain and overdrive pedals) will cause your preamp tubes to go bad faster. Prior to any gigs I would suggest checking your tubes early enough to get replacements should you have a bad one and keep a few handy anyway. It is also a good idea to keep the power tubes that you change out as spares in the event a power tube should go bad (especially at a gig). You could have your head back up and running with time enough to play a few more songs that way instead of having to just kill your set and load out. It is best to just make sure that your tubes are maintained though so these things won't happen at gigs, but strange things happen from time to time. With proper preventive maintenance and keeping spares around you should have no problems or at least you can fix the problem before a total catastrophe.

 

[cesjr]

I know some people who have 10-20 years of their preamp tubes! And only replacing one if they become noisy or microphonic. (Learn something new everyday.)

 

[Russ]

Those people with 10-20 years on their preamp tubes are probably using NOS type tubes. They were designed for up to 10,000 hours unlike today's tubes.