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Topic: hum on LTD400.. |
Dennis Andreatta
From:
hazel crest,illinois,60429
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Posted 13 Jan 2023 2:08 pm |
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| I have an older LTD400 amp. It has a hum which will sometimes stop and then return. I changed the fuse and holder, the switch, preamp capacitors, power capacitors and man the amp sounds great after all that. Still has that hum. My question is....could this be a power cord ? all ideas appreciated... |
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Ricky Davis
From:
Bertram, Texas USA
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Posted 13 Jan 2023 2:33 pm
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Yes; ya gotta check both ground ends of that power cord; make sure it didn't loose good solder connection; heat them up again.
Ricky
_________________
Ricky Davis
Email Ricky: sshawaiian2362@gmail.com |
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Jerry Overstreet
From:
Louisville Ky
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Posted 13 Jan 2023 2:50 pm
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| If this is not a new issue, this won't help, but if it is a new issue that just started after you had it apart, and you had the reverb cables off, reverse them and see it it makes a difference. |
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Dennis Andreatta
From:
hazel crest,illinois,60429
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Posted 13 Jan 2023 2:56 pm Ltd400 Hum
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| I totally removed the reverb cables and still had this hum...the power cord is the original.. |
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Jerry Overstreet
From:
Louisville Ky
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Posted 14 Jan 2023 10:17 am
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| Only other suggestion I have, short of seeing an amp tech, is to rotate the reverb control full CCW...., if you haven't already, I do know that this circuit can cause hum sometimes. Of course, there are other causes, but looks like you've addressed those. Good luck running it down. |
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Cody Stewart
From:
Traverse City Michigan, USA
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Posted 16 Jan 2023 10:34 am
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Inside the chassis, there are several molex (plastic) connectors. If the amps was recently recapped, then the tone stack board must have been removed. I would gently un-plug those molex connectors, one at a time, clean them with deoxit spray and re-connect them. I would also check the rivits of the brackets used to secure the PCB boards to the chassis. Sometimes they get loose causing a grounding issue. I would also check the main ground coming from the power cord with a multi-meter. If none of the above works, I would take it to a professional tec. OR take it to one without doing the above. Working on amps isn't for everyone. The voltage stored in the power supply filter caps can be lethal.
_________________
Bolt On’s: Red Belly, Brown Belly, 73 Sho~Bud Pro~II, Fender’s/Peavey’s. If it doesn't sound like 1968, then I probably won’t like it. |
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Dave Grafe
From:
Hudson River Valley NY
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Posted 16 Jan 2023 1:25 pm
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| What Cody said, those molex connectors are notorious for acting up as they oxidize with age. |
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