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Fisher X-100 noise


bluesboy
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I have a Fisher tube amp that has developed a intermitent scratchy hiss when I first turn it on untill it warms up say for at least 30-40 minutes. This afternoon when I turned the amp on and the noise started I gave the large transformer on the right a rap with my knuckle and the noise stopped for about ten minutes. When the hiss started again I gave it another love tap and it's been quiet for the last 10 or 15 minutes. Could it be the transformer itself is going bad or could it be something as simple as cleaning some connections? Maybe it's time to ship her to NOS Valves.

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  • 3 weeks later...

The noise you describe can result from a high resistance between a tube pin and the socket from oxidation. Before you ship the amp out, remove the tubes and clean the pins with a little WD-40 on a Q-tip. Wipe them dry and then re-insert. Also, be sure to rotate seldom used controls and switches as they are prone to oxidation as well. If all that doesn't work, then it's likely a defective tube.

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The noise you describe can result from a high resistance between a tube pin and the socket from oxidation. Before you ship the amp out, remove the tubes and clean the pins with a little WD-40 on a Q-tip. Wipe them dry and then re-insert. Also, be sure to rotate seldom used controls and switches as they are prone to oxidation as well. If all that doesn't work, then it's likely a defective tube.

Would De-Oxit work better than wd-40 for cleaning the pins and controls?
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I have a problem with WD-40. It promotes rapid oxidizing of the surface. Try cleaning a piece of metal and let it sit for about a week. You will see rust . I tried the stuff on my old Bridgeport milling machine and will never use WD-40 again after having to remove a ton of excessive rust. I would use a brake cleaner with "triclo" in it to remove corrosion on the tube pins. Fisher tube amps and pre-amps were noisy even when the were new. I know because I had several of them in 1965. They also had a very muddy low end compared to the modern stuff. Even the new cheapo SS receivers stuff will blow away the old Fisher low end performance.

JJK

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I have a problem with WD-40. It promotes rapid oxidizing of the surface. Try cleaning a piece of metal and let it sit for about a week. You will see rust . I tried the stuff on my old Bridgeport milling machine and will never use WD-40 again after having to remove a ton of excessive rust. I would use a brake cleaner with "triclo" in it to remove corrosion on the tube pins. Fisher tube amps and pre-amps were noisy even when the were new. I know because I had several of them in 1965. They also had a very muddy low end compared to the modern stuff. Even the new cheapo SS receivers stuff will blow away the old Fisher low end performance.

JJK

My Dads got a Bridgeport milling machine in his shop. I thought you might like to see some of the stuff he's done with metal. He builds scale engines from scratch.

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post-15074-13819568328546_thumb.jpg

post-15074-13819569426628_thumb.jpg

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