Vintage Asylum: Re: Please Explain by kach22i

I don't know if this is the right way to do this, but he explained in a way even I think I can understand. It went like this:

Posted by Ron Oehlert (A) on September 22, 2004 at 18:00:11

In Reply to: Before you plug it in- you must? posted by kach22i on September 22, 2004 at 13:56:52:

If it's good stuff, as a matter of course you should replace all electrolitic-type capacitors BEFORE powering it up. Brand-new power-supply capacitors also dispense with the need to bring up tube amps slowly. Electrolitic-type capacitors simply age-out due to their moist, acidic internal construction. If not too far gone, slow application of power via a Variac or the light-bulb method may re-form their electro-chemical insides for prolonged use, but instant full voltage will short thru aged filter caps that have not been used for quite some time and ruin them. Tube amps should always have a load (such as speakers) connected to the output whenever powered on, even if no input signal is present or a risk of shorts (and so ruin) in the output transformer exists. Sellers that state they have no means of testing but did plug it in to see if everything lights up may have seriously de-valued the item by just such internal shorts; replacement parts will either be expensive or not available. Check vacuum tube availability and cost before you buy.