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Topic: Nashville 400 Reverb Hum |
Max Bernstein
From:
California, USA
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Posted 7 Apr 2013 4:04 pm |
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Hi everyone -
Just bought a used Nashville 400 at Steel Guitars of North County. It sounds great but when I turn the verb up, in introduces hum which goes away once the reverb is off. Any ideas? Thanks!
Max |
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Stephen Cowell
From:
Round Rock, Texas, USA
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Gary Cosden
From:
Florida, USA
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Posted 8 Apr 2013 7:46 am
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| My NV 400 was recently doing the same thing and worse. It sounded like the ground was intermittently breaking contact altogether. I checked the cable to the reverb pan and it tested OK so I just cleaned and tweaked the infamous molex connectors and now it's behaving a lot better but I STILL get some hum when I turn up the reverb. |
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Max Bernstein
From:
California, USA
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Posted 8 Apr 2013 1:26 pm
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| Thanks guys. Yes the reverb works but the noise is quite an issue. |
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Craig Schwartz
From:
McHenry IL
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Posted 8 Apr 2013 2:51 pm
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Max my vegas 400 is doing the same thing, Same as a nashvile, It seems to grow louder at times, until I turn the reverb down again and start over, granted I havent had any capictors changed out ever, I was told to tighten all the 1/4 " jacks by one guy, I`m still humming away when i crank up its reverb knob. I would love to figure this out.
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SO MANY LURES, SO LITTLE TIME.... |
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Dave Grafe
From:
Hudson River Valley NY
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Posted 9 Apr 2013 12:21 pm
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Things to check:
The obvious first thing is wiggling the tank leads and RCA connectors at the tank to see if the problem is there. If this produces no changes in noise or signal then:
Unplug both leads from the tank and identify the return line by touching the tip of each connector with the amp on and the reverb turned up; you will hear nothing when touching the send lead but touching the tip of the return lead connector will produce a noise exactly like what you hear when you touch the end of a guitar cord that is plugged in. Mark this lead for future reference.
Take out any attaching screws and remove the tank completely from the amp and its tolex pouch. There should be a piece of cardboard or the like with metal foil stapled onto it fitted inside the pouch and held tight against the bottom of the tank. If this foil does not cover the entire length of the tank it MUST at least cover the bottom of the OUTPUT end to shield the return transducer. If you do not have this shield you will need to construct one.
Write down the model number of the tank, which will be seven digits, 4EB2C1B or the like, then insert the tank and bottom shield back into the pouch, being careful to note the location of the INPUT and OUTPUT stampings on the case and lining up the jacks with the appropriate holes in the side of the pouch. Return the pouch to its place in the amp and replace any retaining screws.
Plug the leads into the tank, being careful to plug the marked return lead to the tank OUTPUT jack, and the unmarked lead to the INPUT. I make a slightly big deal out of this part as, in addition to a misplaced or missing shield, the symptoms you describe could easily be from the tank simply being plugged in backwards 
If having completed this excercise you can hear the reverb return but have yet no joy then your issue is within the amp itself, so open it up and trace the reverb leads into the chassis to look for bad Molex connectors in the reverb circuit.
If you're still up a creek then the issue is more complex than can I can assess here, but there's smarter folk than I lurking about these weeds so do not despair...good luck! |
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Craig Schwartz
From:
McHenry IL
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Posted 9 Apr 2013 2:55 pm
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mine had no foil, accutronics, I used Metal heat tape on the inside of the cardboard, no more reverb building up , Thanks Again Dave.
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SO MANY LURES, SO LITTLE TIME.... |
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Stephen Cowell
From:
Round Rock, Texas, USA
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Posted 9 Apr 2013 5:17 pm
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| Max Bernstein wrote: |
| Thanks guys. Yes the reverb works but the noise is quite an issue. |
Check that no extension cords are laying in the bottom of the amp... the tank is susceptible to hum, even sitting your amp on top of an extension cord can cause what you're hearing.
You can divide and conquer... unplug the RCA's from the tank. Short the one from the tank output (the one that buzzes when you touch it)... do you still have hum? Then the hum might be coming from the circuit inside the amp. No hum? Then the hum is coming from the tank circuit. The ground wire should only be connected to the tank case at one location... if both RCA's grounds are touching the tank you can get 'ground loop' hum. Both grounds should connect to the transducers in the tank, but the tank chassis should only connect to one of the grounds, the output IIRC.
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New FB Page: Lap Steel Licks And Stuff: https://www.facebook.com/groups/195394851800329 |
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Jim Palenscar
From:
Oceanside, Calif, USA
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Posted 10 Apr 2013 7:00 am
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| Bring it on back Max- I'll go through it for you- or get you another one- no big deal~ |
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Max Bernstein
From:
California, USA
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Posted 11 Apr 2013 11:22 pm
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| Thanks Jim, you're the best =) On the road til the 27th, will see you then! |
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