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Power up tube amps every once and awhile?


BadLife

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I was reading another thread and saw the bit about buying an amp that had been in storage for a while. And got to wondering if maybe I should turn on an amp that I don't use too much every once and awile? I don't have that many but one that I have had for a long time only gets messed with once in a blue moon. How often should you turn the amp on to keep it from getting messed up?
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Originally posted by henrysb3:

Even if you don't plug it in, it might be a good thing to move the knobs back and forth every once in a while to slow the corrosion that takes place in the pots.

Excellent suggestion, never thought of that. Same would apply to pots on guitars too. I have electric motors in stock here at work and I go out about once a month to give them a spin so the bearings don't flat out in spots.
I was born at night but I wasn't born last night...
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As Ricochet stated the problem here is with the aluminum electrolytic capacitors.

 

As a general rule: Store your gear in a cool place and apply power every 6 months for 30 to 60 minutes.

 

Storage temperature is the biggest factor, the higher the ambient temperature the faster the caps will degrade. What happens is the electrolyte starts to react with the aluminum foil anode; this increases the spec called leakage current. This is DC current flowing from the anode to the cathode inside the cap, exactly what a cap is Not supposed to do. As leakage current increases the capacitance decreases and its operating temperature increases until the cap either explodes or blows the vent open and sprays electrolyte all over everything. If were lucky it just shorts out and blows a fuse.

 

Another thing is a cap that goes from 0 Volts to its full working Voltage is going through a lot of stress. This is normal and happens in most equipment every time we turn it on. Its common practice for engineers to place bleeder resistors across caps so when the power is removed the cap can slowly discharge making it safer for technicians to work on. Unfortunately this is bad for the caps but safety is more important than component longevity. I brought this up because I recently read somewhere on the net that people where telling others when their done playing to leave their Stand-by switch ON and kill the power, that this would help to discharge the caps. Which is true, but why would one want to? I definitely Dont recommend doing this.

 

As far as potentiometers go there are two different things that happen.

One is the carbon/resistive track just wears out and develops holes in it. At that point it just needs to be replaced.

The other is dust/dirt on the carbon track and/or stuck under the wiper that rides on the track. In this case using a cleaner/lubricant made for this purpose can do the trick.

 

For High Dollar Vintage equipment there is a rejuvenation process for capacitors that have not been powered up for many years. Its tedious and time consuming but you may be able to find a tech that will do it.

 

For potentiometers that are not replaceable there are methods of rejuvenating them, its just finding a tech willing to do it with little guarantee of success.

When i get big i'm gonn'a get an electric guitar...

When i get real big...

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