Help with a ampage problem

Discussion in 'Ampage Area' started by Wjensen, Jun 4, 2019.

  1. Wjensen

    Wjensen Electromatic

    52
    May 25, 2019
    Raleigh, NC
    I have a Fender Mustang I (v2.0) 20 watt amp that I bought for practice last August. The thing has worked perfectly on the channels I use, which tend to be clean channels with a touch of reverb. Suddenly it is making noise (I call it white noise) when I turn it on.

    In tracking down the problem, I put my hand across the strings and presto, no more noise. Remove my hand and the noise returns. I touch the metal part of the guitar cable (Live Wire) and presto, the noise goes away. I remove my hand and the noise returns. Thinking it might be the Gretsch 5420 feeding back, I switch it out for my Epiphone Les Paul that I used before I got the Gretsch. Same problems and solutions.

    Hmmm!

    I think it is my amp. As amps go, it was relatively inexpensive. Is it worth having a shop look at it or should I consider it a loss and go get something else. My instructor uses a mini Marshall that sounds very nice. No reverb, but this is a practice amp. Acoustic also makes a practice amp, but I am not familiar with how it sounds.

    Thoughts please,

    Wade
     
    MKunie likes this.
  2. markeebee

    markeebee Country Gent

    Have you tried a different cable?
     
    PlasticOcean and wildeman like this.
  3. wildeman

    wildeman Gretschified

    May 10, 2015
    norcal
  4. thunder58

    thunder58 I Bleed Orange

    Age:
    60
    Dec 23, 2010
    tappan ny
    Where are you using this amp ? Home ? another location ? Has anyone installed new lights in the area or change light bulbs from incandescent to a florescent ? ( sounds silly ) I was an electrician years ago . Poor ground at the recepticle maybe also ...... just throwing it out there
     
  5. Scooter127

    Scooter127 Gretschie

    354
    Feb 25, 2019
    USA
    Sounds like a grounding problem to me, although grounding problems usually cause the typical 60hz hum. The same hum you often hear when walking past transformers.

    IF it's a grounding problem it could be the amp, and it could also very well be the electrical circuit you plug into. Try plugging the power cord into an outlet in another room, or one you know not to be on the same circuit.

    Outlet testers are cheap (under $10) and I consider mine essential for working on anything in my house involving circuits. Not only will they tell you if the circuit is wired properly, but they also confirm that I flipped the right breaker to turn the circuit off.

    This isn't the same one I have but it's pretty much the same thing:
    https://www.homedepot.com/p/Commercial-Electric-Outlet-Tester-OT-112R/206029154

    Plug it in and if you get two yellow lights in the right spot, you know the circuit is good. The previous owner of my house lefty behind some seriously sketchy work and I've corrected two circuits using this little gadget.

    upload_2019-6-4_12-25-24.png
     
    benjwri, Ricochet and wabash slim like this.
  6. hcsterg

    hcsterg Country Gent

    Feb 13, 2012
    France
    Hi Wjensen,

    I used a Mustang III combo (100W 1x12") from the music school and he had some issues :

    1 - bugs like complete stop while playing, problems of sudden settings changes...

    This was due to heavy duty transportations problems : this amp is not designed to endure severe conditions. PCB moves and disconnects, so I had to foam them to block them in place several times. A lightweight, but nonetheless fragile item... Way much more fragile than a good old Fender tube amp !

    2 - adverses noises, lost of presets.

    I reloaded the software of the amp, and this adressed the problem. Fortunately, thanks to Fender Fuse, I saved my presets beforehand.

    This made me think that you may be able to correct your hiss issue by doing what I did on point 2 -

    A+!
     
  7. wabash slim

    wabash slim Friend of Fred

    Age:
    69
    Feb 10, 2010
    lafayette in
    Sounds like a grounding issue to me as well. It could also be in your guitar, too. Light dimmers, neon and fluorescent lamps, motors, and transformers are all possible noise sources. A wonky pedal or cable could also be the issue. Go to a simple cable between your guitar and amp. Try a different cable. Move around the room, turn 90 degrees, away from the amp, see if the issue gets better or worse. Add pedals one at a time. Good luck finding the culprit.
     
  8. Wjensen

    Wjensen Electromatic

    52
    May 25, 2019
    Raleigh, NC
    Let's see, I did try another cable. Happened to have a spare (because 2 is one, one is none, right?). Same problem. I also plugged in my Epiphone Les Paul, which doesn't have any problems itself. Same problem. The amp is my practice amp, so stays in the same position since I got it. It doesn't move and there have been no changes to the lighting or the electrical system. It has been plugged in to the same circuit the entire time. I have pretty much isolated the problem to the amp itself.

    I believe it is a grounding issue in the amp. The effect is called hand capacitance in the amateur radio community. It shows up a a tuning instability as your hand moves around the unit. But I don't know where to add a ground to an amplifier. In radio, there is an wing nut on the unit that you can ground, and you can ground the antenna.

    Wade
     
  9. hcsterg

    hcsterg Country Gent

    Feb 13, 2012
    France
    Think of the Mustang amp rather as a computer, full of SMD, etc... Not easy to troubleshoot.

    As Scooter127 and wabash slim mentioned : it's possibly a GND problem inside the amp (but don't discard definetly the software issue though), and probably a now missing GND due to a bad contact.

    I'll check by starting at the input jack : search for continuity there, and track the GND circuit then. I would supsect a bad solder joint somewhere, maybe a cut trace, cut flat cable, poor connector contact, etc... A pain to locate !

    Good luck ! ;)

    A+!
     
    MKunie likes this.
  10. Scooter127

    Scooter127 Gretschie

    354
    Feb 25, 2019
    USA
    milocj and pmac11 like this.
  11. Henry

    Henry Gretschified

    Apr 9, 2014
    Petaluma
    Most likely environmental electric noise picked up by the guitar um pickups. My guess is your guitar/amp IS grounded, that's why the noise goes away when you touch the guitar. Walk around the room when it makes the noise, my guess is it varies in intensity as you move around.

    Have you made any changes in your environment like getting or moving a new TV, computer, lighting, etc.?
     
  12. Henry

    Henry Gretschified

    Apr 9, 2014
    Petaluma
    Heres another test. Find something in the same room that IS grounded, like a computer case. Go up to that object. Touch your guitar, let it go, touch the other grounded object. If the same thing happens touching the guitar and the other grounded object, then it probably isn't an amp ground issue.
     
  13. Wjensen

    Wjensen Electromatic

    52
    May 25, 2019
    Raleigh, NC
    Thanks guys. I will attempt to find the issue. But it sounds like having a professional look at it would perhaps cost more than getting a new amp.

    Wade
     
  14. hcsterg

    hcsterg Country Gent

    Feb 13, 2012
    France
    Yes, that's possible... o_O

    A+!
     
    Wjensen likes this.
  15. Gretschtim1

    Gretschtim1 Country Gent

    Dec 4, 2012
    Dundalk, Md
    Lots of good suggestions here. Here's a few more to try.
    Try moving the amp to another outlet in another room?
    Also if an Air Conditioner, Refrigerator, or any other appliance is on the same circuit it could send noise into your amp via the power line. I was getting a weird static sound through an amp. The sound would come and go. Turns out a space heater that was upstairs was going on and off. When ever it cycled on the noise appeared. I moved the heater to another outlet and the noise was gone.
    Also if you have a removable power cord on the amp make sure it is pushed into the back of the amp tightly.
    Good luck and I hope you find the solution.
     
  16. Scooter127

    Scooter127 Gretschie

    354
    Feb 25, 2019
    USA
    You never know. It may well be something "stupid simple" and cheap.
     
  17. wabash slim

    wabash slim Friend of Fred

    Age:
    69
    Feb 10, 2010
    lafayette in
    "Spurious Emissions"! (Great band name, by the way)
    In our theaters, all of the audio power went thru isolation transformers. With over a million watts just in stage lighting, and adding in three phase HVAC motors, house lights and all of the other AC being used in the building, we had to be extra careful with noise thru the PA. Neon and fluorescent lights, SCR dimmers, motors of all types, and other sundry sources can cause noise. There was a guy in my town whose illegally amplified CB radio was bleeding into TV broadcast and cordless phones. My Dad's fish tank heater would cause noise on our TV. Hard telling just where the noise source is.
     
  18. Gretschtim1

    Gretschtim1 Country Gent

    Dec 4, 2012
    Dundalk, Md
    Yeah weird how it happens. A while back we bought a new electric stove and every time a burner would cycle on it would put a click/pop in my studio monitors. It took a while to figure out where it was coming from.
     
  19. wildeman

    wildeman Gretschified

    May 10, 2015
    norcal
    I was given a Mustang a while back that was intermittently shutting down, i just followed the signal path until i found a cold(unsoldered) joint and fixed it, not very hard at all. These amps are not impossible to repair ( sometimes) so give it a look, the problem may be obvious.
     
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