Nashville 400 hum

Don Burrows · From: Ashtabula, Oh. USA

I have a Nashville 400 that hums when the reverb is turned up. If you turn the reverb off it quits. Also if you plug a jack into the pre-amp in the back, with or without anything else being plugged in the humming quits.
What could it be?
Thanks, Don

Jack Stoner · From: Kansas City, MO

Check the reverb I/O molex connector on the underside of the chassis. That's usually the source of hum/noise in the reverb. Usually just removing the connector and spraying contact cleaner on both the female and male pins and then plugging the connector back in will take care of it.

Don Burrows · From: Ashtabula, Oh. USA

The molex connector has been hard wired by somebody in the past, and all the wires seem to be tight where they sodered it.
Don

Bill Crook · From: Goodlettsville, TN , Spending my kid's inheritance

Disconnect the leads from the reverb pan..... and see if the hum goes away.

It may be that the leads to the spring unit is reversed. A good indication of this is that the reverb sound will be somewhat weak but still work. it's common problem found after "fixes" on the reverb molex plugs are made.

Don Burrows · From: Ashtabula, Oh. USA

Bill, I tried reversing the leads and didn't make any difference.
Could it be in the pre-amp jack, being that when you plug a jack into it , it quits?
Anybody got any other suggestions?

Thanks Bill

Don

Bill Crook · From: Goodlettsville, TN , Spending my kid's inheritance

C Dixon · From: Duluth, GA USA

When you say the molex connectors have been soldered, I am curious as to just how they did this.

Jack Stoner is correct, 99% of the hum when the reverb control is turned up, IS in fact due to a dirty contact in one or more pins on the molex connector. This is common on the Peavey Nashville 400.

Check to make sure that the molex connector is in fact not been soldered, but just appears tight. They are very tight by design but still are prone to dirty connections between mating pins.

Try this experiment. Turn up the reverb to where the hum is loudest. Reach under the chassis and wiggle the molex connector. If there is a change in the hum and/or elimination of the hum, I can almost guarantee you there is a pin or more that is not making good contact.

If this is the case, remove it. It may be very very tight. Then as Jack suggest, spray it with contact cleaner available from most any electronic supply house. Then reinsert it. Not a bad idea to disconnect and reinsert it several times to make sure you did get all the pins real clean. So they are ideed making good contact.

Good luck and God bless you with whatever you find to be the cause,

carl

Mike Brown · From: Meridian, Mississippi USA

If any of the above suggestions fail to repair the 'hum' problem, please let me know and I will be glad to assist further.

Mike Brown
Peavey Electronics Corporation

clive swindell · From: Huddersfield, West Yorkshire, UK

I have had the same problem and my technical man says it is the power transformer which is too near the reverb tank and which is interfering with it. The answer is to fit a different transformer which he is on with.

You can ask him at keith.knutton@cwcom.net if you want the details.

Jim Smith · From: Midlothian, TX, USA

If that's the case, why not just move the reverb tank?

clive swindell · From: Huddersfield, West Yorkshire, UK

Yes, but where do you move it to? It is sat in the bottom of the cabinet.

Jim Smith · From: Midlothian, TX, USA

Evans mounts some of theirs on the side.

Bill Myrick · From: Pea Ridge, Ar. (deceased)

I once bought a Peavey Musician III Power head in a pawn shop that acted that way and come to find out someone had put the reverb pac back in backwards which put it too near the transformer. Can it be turned around 180 degrees ?

Jack Stoner · From: Kansas City, MO

The physical location of the reverb in the Nashville 400 should not be a problem. There are many amps out there that don't have excessive hum problems. The export model with the different transformer/voltage is a separate problem.

Plugging into the PREAMP out should not do anything as this is a parallel output and the same signal that goes to the POWER AMP IN. However, if a plug was put into the POWER AMP IN then there will be a difference. Maybe you are plugging in to the POWER AMP IN instead of the preamp out.

If you are putting a plug in the power amp in then the problem still goes back to the reverb circuit and back to either the reverb I/O connections or a reverb cable. Since the cables are soldered instead of the molex connector, it is possible that there is a bad solder connection on the circuit board for the reverb I/O. Whoever soldered the wires on could have used too much heat and screwed up the solder connection to the circuit board. Where the male pins are soldered on to the circuit board is a good place to check.

I would suggest you either take it to an amp tech or send it to Peavey for repair.

Louie Hallford · From: denison tx

I have the same problem with hum at my apartment where I keep my music. When I play out however it quietens down making me think it is grounging problem in the wiring at my apartment.....I have no florescents which will also cause hum.

[This message was edited by louie hallford on 16 January 2001 at 07:38 PM.]

Mike Brown · From: Meridian, Mississippi USA

We'll be glad to take a look at the amp if you will send it to;

Peavey Electronics Corporation
Hwy. 80 East
Meridian, MS 39301

However, first let's discuss what the possible problems might be by phone. I can be reached here at Peavey by phoning 1-877-732-8391 in the U.S..

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