Musicians Roadhouse

My VM's (2466) power valve decided to die quite recently, only a few weeks after i acturally got it (though it was an ex display head its still annoying). Anyway, i got a matched new set... what now? Do you just take out the dead one and replace it (and replace another one because apparantly you need to) and away you go or is there more?

Im new to valves lol

That's tough. Replace them in corresponding pairs at the same time. They may not bias up close to each other otherwise, for one thing. It's best to keep them in pairs so they have the same amount of wear too. Even though there are four of them, the corresponding pairs work together.

You'll need to check the bias also, which is akin to setting the idle speed on a car motor. All you need is a decent volt meter. There are handy points in the VM where you take a voltage reading, which because it's taken across a precision 1 ohm resistor, can be directly converted to amps (Ohm's Law), which is what you're concerned with. I.e., I (amps) = E (volts)/1 in this case. There is a small pot to adjust the current with the range being between 72 to 80 mA. That's it. The most difficult part is getting the chassis out of the cabinet.

There are past posts you can search that give a detailed account of the procedure so make sure you read and understand those before attempting this. It must be done with the amp fired up. The voltages in there are around 450 volts (potentially even with the amp off!) so make sure you know what you're doing and work safely to avoid electrocution. :high If you're not sure, get an experienced person to help you.

haha... yeah im 17 and i know bugger all... i think ill go with the help lol
cheers man:)

Maybe not a bad idea. After all, it pretty much only needs done when changing output tubes. I hope I didn't make it sound too intimidating. In your case, that was some very bad luck, having a tube go out so soon. :violin

The new set should last quite a while longer, especially if you don't use an attenuator. Be sure to hang onto the odd matched pair for spares. Best of luck.