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Topic: Nasvhille 400 slightly fuzzy distortion, any thoughts? |
Ian Sutton
From:
San Francisco, CA
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Posted 16 Dec 2019 9:01 am |
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I have an early 90's Nashville 400 and have noticed that sometimes on startup there is a quiet, fuzzy, distorted sound happening under its regular clean, clear tone. Usually it goes away after a few minutes of play.
I'm pretty confident working on amps, but just not sure where to start the troubleshooting. I'm trying to get this amp road-ready for some touring in the new year. Your thoughts would be most appreciated.
Here is what I know so far:
-Pre-gain knob set correctly
-Have tried with different speakers, same issue
-Reverb is off (but not disconnected from the circuit)
-Visually, the capacitors look good but they could still be original
Thanks in advance!
Ian
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Some gear. |
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Steven Paris
From:
Los Angeles
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Posted 16 Dec 2019 9:46 am
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I'd bet that it's a power supply filter cap. Since they are ~ 30 years old, probably not a bad idea to replace them.
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Emmons & Peavey |
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Ian Sutton
From:
San Francisco, CA
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Posted 16 Dec 2019 10:08 am
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Thanks Steven, yeah, was thinking of starting there. Visually, the caps all look good, but I know that doesn't necessarily mean they're up to spec, especially after 30 years.
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Some gear. |
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Lee Baucum
From:
McAllen, Texas (Extreme South) The Final Frontier
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Posted 16 Dec 2019 11:07 am
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Here is some interesting reading, in case you have a Black Widow speaker. It may, or may not, be helpful:
Click Here
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Lee, from South Texas - Down On The Rio Grande
There are only two options as I see it.
Either I'm right, or there is a sinister conspiracy to conceal the fact that I'm right.
Williams Keyless S-10, BMI S-10, Evans FET-500LV, Fender Steel King, 2 Roland Cube 80XL's,
Sarno FreeLoader, Goodrich Passive Volume Pedals, Vintage ACE Pack-A-Seat |
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Ken Fox
From:
Nashville GA USA
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Posted 16 Dec 2019 12:19 pm
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| Most likely culprit is usually the power amp in jack contacts. Try a jumper from preamp out to the power amp in jack. |
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Tommy Shown
From:
Denham Springs, La.
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Posted 16 Dec 2019 12:42 pm
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| Or check your molex connectors. |
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David Nugent
From:
Gum Spring, Va.
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Posted 17 Dec 2019 6:09 am
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| Having a similar problem with my Nashville 112 and it is usually accompanied by a slight loss in volume, believe that Ken's suggestion may be worth a try. When the 112 starts acting up (normally at start up when not being used for a time) I simply dime the volume controls and hit the strings lightly until volume level returns to normal. |
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Ken Fox
From:
Nashville GA USA
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Posted 17 Dec 2019 9:58 am
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Having worked on around 500 plus Peavey steel amps I have seen the number one issue to be a high resistance on the contacts on the power amp in jack
Other issues:
Mid pot causing a popping sound when turned, very loud. Pot must be cleaned or replaced
Post gain and Reverb pots scratchy and need cleaning
Molex connector for reverb exhibits poor connectivity
Pins at chassis need to be cleaned with a Qtip and alcohol, female contacts on Molex need to be tighter
Input jack contact dirty, need to be cleaned and or realigned so they close properly
Molex connector used for speaker connection needs to be serviced same as reverb connector. Later amp had the wires soldered to the male pins at the chassis to avoid problems |
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Justin Griffith
From:
Taylor, Texas, USA
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Posted 18 Dec 2019 8:26 am
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Check the speaker. That foam gets in the magnet and the voice coil drags. Clean that up and see. I’ve had several do that to me.
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Emmons/Sho~Bud/Blanton, Fender/Peavey.
Telonics pedal |
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Ian Sutton
From:
San Francisco, CA
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Posted 18 Dec 2019 9:45 am
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Thanks for all the replies.
As I mentioned in the original post, I've ruled out speaker issues straight away nor am I experiencing any scratchy pots or reverb issues, so will run down Ken's laundry list where applicable and see what I can see.
I'll report back to those of you playing along at home!
Thanks again!
Ian
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Some gear. |
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Bill C. Buntin
From:
Cleburne TX
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Posted 18 Dec 2019 1:45 pm
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Ken, great tip. I’ve got a session 400 that has this problem too. I’m looking into this when I get time
Bill |
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Tony Prior
From:
Charlotte NC
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Posted 19 Dec 2019 6:20 am
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anyone who owns and travels with a PV Steel amp needs to carry a 6 inch 1/4 male to male cable ! They are great amps but every now and then...
Go back and read what Ken posted above.
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Emmons L-II , Fender Telecasters, B-Benders , Eastman Mandolin ,
Pro Tools 12 on WIN 7 !
jobless- but not homeless- now retired 9 years
CURRENT MUSIC TRACKS AT > https://tprior2241.wixsite.com/website |
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Steven Paris
From:
Los Angeles
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Posted 20 Dec 2019 12:06 am
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| Ken Fox wrote: |
| Having worked on around 500 plus Peavey steel amps I have seen the number one issue to be a high resistance on the contacts on the power amp in jack |
Thanks for the tips, Ken! Your contributions to the Forum are outstanding!
What brand is that normalling jack on the Peaveys? What brand would be an upgrade and eliminate the problem?
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Emmons & Peavey |
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