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Post by singlecoiler on Dec 26, 2018 10:29:07 GMT -7
So this is an older anniversary model 18 with reverb. Problem is intermittent noise. Mostly a loud white noise, a thick hissing sound sometimes with crackling and often ends with a loud pop. Sometimes the noise can be initiated by turning up the volume or master volume control. I have been making some tube swaps, pre amp and power tubes. i replaced everything except the rectifier a while back, that did not solve the problem. The problem will disappear for a time and then comes back. I recently re installed the older el 84s and a new tube in V 1. The amp has been quiet with this config for a an hour or so now but only time will tell. On one notable occasion recently the sound was initiated by my guitar patch chord touching the input when plugging in. So, i'm wondering, do you think this is likely a power or pre amp tube problem or a grounding issue or even a burnt out capacitor / resistor?
Thanks for your thoughts on this.
Peter Z (singlecoiler)
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Post by zpilot on Dec 26, 2018 11:01:17 GMT -7
I'd start with a good cleaning of the switching contact points of the input jacks. If you have an effects loop I'd clean those jacks too, or at least insert a short patch cable to jumper them. You will need to remove the chassis to clean those jacks.
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Post by singlecoiler on Dec 26, 2018 11:03:11 GMT -7
Cleaning as in de-oxit ?
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Post by zpilot on Dec 26, 2018 11:09:42 GMT -7
Well mostly. I slide a small piece of very fine sandpaper (400 grit) in between the contacts with some D5 on it. If you don't have any sandpaper then just using regular paper will be fine. Anything just to give the cleaner some help clearing out the corrosion and crud.
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Post by singlecoiler on Dec 26, 2018 11:48:17 GMT -7
Just cleaned the amp and noticed something interesting after re-installing the chassis. I can initiate the noise when simply pushing on the face plate! Not sure what this means. The top 4 screws are as tight as i can get them. Any thoughts?
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Post by daddyelmis (Greg) on Dec 26, 2018 12:02:07 GMT -7
In addition to the cleaning, I’d go through and tighten all jacks and all bolts. Doc has a great video on annual maintenance - including tightening everything to ensure good grounding.
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Post by singlecoiler on Dec 26, 2018 12:15:09 GMT -7
OK! I think i got it. I noticed a thin 12 inch strip of tolex had become detached from the chassis where it meets the top of the face plate, essentially bunching up and making it impossible to get the amp completely snug in the cab. I cut out the bunched up tolex and re-installed the amp. All seems well again! Thanks for your help.
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Post by Maddog on Dec 26, 2018 13:34:46 GMT -7
I can initiate the noise when simply pushing on the face plate! Pull the knobs off and check the nuts around the pots.....especially in the area where pushing the faceplate in, initiates the noise.....If they're loose, incomplete grounding can arise....
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Post by zpilot on Dec 26, 2018 15:05:31 GMT -7
OK! I think i got it. I noticed a thin 12 inch strip of tolex had become detached from the chassis where it meets the top of the face plate, essentially bunching up and making it impossible to get the amp completely snug in the cab. I cut out the bunched up tolex and re-installed the amp. All seems well again! Thanks for your help. We will place that little tid-bit in the trouble shooting list. That's the first time I've heard of it happening. Thanks.
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