Bottlehead Forum
Bottlehead Kits => Crack => Topic started by: DanceTomato on November 18, 2018, 02:56:21 AM
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I hear static / popping / crackling noise whenever I touch or turn the volume knob. It starts from 9 o'clock all the way to max volume position without any RCA connection, with only the Power Cable, inserted both tubes and phono is a Senn HD600 plugged inside. The amp is dead quiet if I don't touch anything, the static appears if I make contact with the amp.
Furthermore, the popping /static noise is quieter if I - Eg: turn the knob with my left hand while touching parts of the top-plate with my right hand.
I have tried the following - re-flowed solder to some of the soldered joints, tapping the top plate to check for any weird noises/ loose connections, turned off cellular phones, changing powering socket outlets, changing different headphones.
I am seeking for some guidance on how to solve this issue please and if anyone knows how to troubleshoot, I would really appreciate it.
Thank you
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I experienced something similar after adding a new pot to my Crack and solved the problem by reflowing the solder joints. I would double and then triple check all the wiring to the pot for potentially weak solder joints - and that includes wiring from the pot to parts connected to it -- in particular the connection to ground. Try giving each solder joint a good reheating and a fresh zap of solder. When I do this, I wait to see the old solder liquefy, and then wait an additional second for the heat to transfer to both wire and contact, and then add a bit of solder -- if I add solder too soon, I'm just building up an even larger cold solder joint. I also check that the wire ends are well crimped to the solder lug -- if the wire moves when I touch it with the soldering tip there's a pretty good chance it will spring back again when I remove the soldering iron, resulting in a cold joint.
If that doesn't solve the problem, the contacts of the volume pot may be oxidized a bit. There are a bunch of aerosol cleaners made for fixing this. One example is Deoxit. Search for "Deoxit pot cleaner".
Hope this helps,
Derek
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Do you have grounded power outlets where you live? How is the DC resistance between the #8 screw by the IEC power entry module and terminal 3?
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@PB The #8 ground screw & #3 Terminal shows 0 using a grounded socket.
@ Deke609 Next I will try to re-flow solder to the volume pot connectors.
Problem solved - tightened the ground screw from the top side and no more static noise.
But... New problem... after spraying contact cleaner inside the volume pot, it is now very stuck. :(
Edit: What kind of lubrication can I spray to get it moving again? Will some WD-40 Dry lube spray work?
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Generally you don't want to spray anything into a brand new pot. What kind of contact cleaner did you use?
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... after spraying contact cleaner inside the volume pot, it is now very stuck. :(
That's very odd as DeOxit should have the opposite effect. You might want to double check that you didn't get any on the post that connects to the knob. If you've effectively greased the post, the tightening screw on the knob may not grab and will just spin. If you remove the knob and clean the post, does the post turn using your fingers?