Question about Amplifiers & Preamps

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I have a Peavy "Classic 30 BT" guitar amplifier that stopped working. When the power switch is ON, the pilot light glows but the vacuum tubes don't even glow. Using a volt meter, I found that 120 Vac is at the input leads of the main power transformer but there is no voltage at the secondary leads. I unsoldered the transformer leads and measured an open circuit across the input leads of the transformer. I unsoldered the copper band that wraps around the transformer and removed the plastic covers over the transformer terminals and windings. I found a small cylinderical component taped against the transformer windings that is connected in series with the primary 120 Vac windings. My Ohm-meter shows this component as an open circuit, even when I reverse the Ohm-meter leads to reverse the Ohm-meter polarity. I am guessing this is a thermal protective device for the transformer and it has failed OPEN. Does anyone know what this device on the transformer coil is and how I might find a replacement component so I can repair the transformer and the get the amplifier working again?

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Hi and welcome to FixYa,

I have to agree with you that that component is a thermal fuse. In my country, they are readily available in most electronics/hobbyist parts store. These components are also used for small motors and therefore would also be available in some (but not all) kitchen appliances parts stores. A temporary workaround is to install an ordinary fast blow fuse.

Just a start, do postback how things turned up or should you need additional information. Good luck and Thank you for using FixYa.

Posted on Nov 29, 2008

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