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Fender Rumble 150 in need of tlc. Can i fix?

Discussion in 'Amps and Cabs [BG]' started by Chaotic Pocket, Mar 16, 2019.


  1. Chaotic Pocket

    Chaotic Pocket

    Mar 16, 2019
    Hi there. I own a Fender Rumble 150, and it does strange things. I would like to possibly fix it myself.

    "The Strange"

    1. Volume knob is all the way down, yet it continues to be LOUD.

    2. When messing with knob, its scratchy, and levels fluctuate wildy. Sometimes i can just tap it, and it can go from very quiet, to very loud, and vice-versa.

    3. If i give even the slightest tap to my bass output...not the amp input...the bass output, it can, and quite often will pop very loud. I know its not my bass or cord, as i have plugged into other rigs, and nothing happens. It plays great.

    4. It hisses...oh does it hiss. I use a tascam dr-22wl to record, and that hiss is very prevalent in my playbacks.

    I have yet to pull the head, as i really have no business messing with that stuff, and am afraid to do more harm than good.

    I was just wondering if anyone recognizes these symptoms, and can diagnose? Really trying to avoid spending alot of money and maybe correct the problem myself. And, too, i figure i need to learn some of this stuff, as i have gotten pretty serious about my playing recently. I know this is a good amp for someone in my situation, so id rather not see any "get a better amp" replies...though now i most likely just invited a whole slew of them in.

    Thank you in advance for any help that can be offered.
     
  2. sissy kathy

    sissy kathy Back to Bass-ics Gold Supporting Member

    Apr 21, 2014
    Arbutus, MD
    Welcome to TalkBass.
    Sounds like it needs new pots to me. I would take it to a repair station. Those pots are likely soldered directly to the board.
     
    Last edited: Mar 16, 2019
  3. 96tbird

    96tbird PLEASE STAND BY

    Sounds like dirty volume pot giving you the volume problem. If you know what you’re doing you can pull the head and clean the pots with contact cleaner.

    Hiss can be a sign that the signal may be driven too high somewhere. According to the block diagram All the knobs control the preamp section and The power amp is always (potentially) running wide open. If you are pumping too much through the preamp, the noise from the pre gets passed to the power and is amplified too.

    The tone stack is +- 12db. You really want to begin with them set flat (middle) you don’t want to be cranking them because they add noise along with boost, especially the mid and high knobs. Cutting what you don’t want to hear is best so if you want highs, turn the lows down. Then you can turn the volume up a bit to compensate.

    But this all depends on the pots and contacts (in the jacks) being clean. There is a breaker contact on the fx return that needs to be clean as well.

    Or the hiss can be a problem with board components and cleaning contacts won’t fix it.

    So, yeah, it needs to be taken to a tech, describe your problems and get it cleaned up and tested for bad components to see if it can be fixed. Finding a local shop to do it will be the most frustrating part. Check the Fender website for service centers and start calling to see if they actually will help you on site without sending it away for service. Ask people in your area for electronic shops that will do the work: not like the old days where there was tv repair shops everywhere. You can try cleaning if you’re up to it and do some research on how it’s done. Plenty of YouTube info on this stuff.
     
  4. agedhorse

    agedhorse Supporting Member Commercial User

    Feb 12, 2006
    Davis, CA (USA)
    Development Engineer-Mesa, Product Support-Genz Benz
    That's a simple amp for a qualified tech. You might start with a Fender authorized service center. Note that many shops won't service products that have been messed with in a failed DIY repair attempt.
     
    BassmanPaul likes this.
  5. Agreed! It’s TECH TIME! Better to let someone who knows what he/she is doing rather than you making a $50 repair into a $500 one.
     
    Jaymo likes this.
  6. Chaotic Pocket

    Chaotic Pocket

    Mar 16, 2019
    Wow. Thank you for the feedback. Ill have to look up what pots are. I dont know this lingo....yet. Ill see what I can find out, now that i have an idea where to start. I'm a quick study, and have always been very interested in learning how the thunder within these boxes is produced, but i also know when im in over my head. Hopefully, its something simple.

    Again, thank you.

    P.S.- Is this also the possible cause for the super loud cracks if i jostle the output on my bass?
     
  7. sissy kathy

    sissy kathy Back to Bass-ics Gold Supporting Member

    Apr 21, 2014
    Arbutus, MD
    First a 'pot' is a potentiometer. a technical term for a volume or tone control. The loud cracks when you jostle the output of your bass are from the cable and output jack making intermittent contact with one another. The jack could be loose or need a new one. Try tightening the nut around the jack first.
     
    Lobster11 likes this.
  8. Chaotic Pocket

    Chaotic Pocket

    Mar 16, 2019
    No. As I stated in the first post, i have plugged into other rigs, with the same cable, and nothing happens. It is from the rumble. Or perhaps i just dont hear it on the others because theyre setup and maintained correctly.
     
  9. 12Toes

    12Toes

    Apr 19, 2001
    Lexington, KY
    The scratchy/volume spike pot is a rumble "thing". My v3 200 combo does it as well. So common on those models that its not uncommon. A lot of tb'ers have raised the issue as well. No easy fix is the consensus I've read, but I gave up looking long ago. So maybe someone has stumbled onto a "eureka" solution that I haven't seen.

    Doesn't matter which bass you plug in, doesn't matter which cable you use, doesn't matter what power outlet you plug into, doesn't matter if it's a full moon. It's a flaw. Either design or manufacturing.

    Closed pots, so de-ox spray is ineffective. Repeated knob rotation can quiet things down, but you'll have to do that every time you feel like using the amp. And the problems will still be there in some version. Only less of it.

    Shame, the tone on mine is usable on a pro level. The tone would do fine for a live room / d-i combination. And that usable tone is so easy to dial in. Again, a shame. Too flaky for studio use. Maybe it'll produce pops and scratches, maybe it won't.

    Read some posts of owner's simply not adjusting the amp's volume after powering it up once a sweet spot on the knob is discovered. Sounds like a fix someone would give you selling a lawn mower at a yard sale. "It'll start, but you'll need to re-seat the spark plug every three weeks".
     
  10. agedhorse

    agedhorse Supporting Member Commercial User

    Feb 12, 2006
    Davis, CA (USA)
    Development Engineer-Mesa, Product Support-Genz Benz
    You might start with an authorized Fender service center, I don't believe it's an inherent issue and I haven't seen anything that would confirm that this it a true assumption. But then again, the internet is full of people who are convinced that the earth is flat and that we never landed on the moon, so YMMV.
     
    G-Dog and Warpeg like this.
  11. 12Toes

    12Toes

    Apr 19, 2001
    Lexington, KY
    I chimed in to let the original poster know of what my searches about that model found. Figured it may be of use to him. I had experience with the product, and "nothing to see here" wasn't my experience. In fact, my experience was his experience as well. So I let him know.

    And yes, a certified service center is the best option. Some owners may be interested if there is a quick fix, or I've they're using the product incorrectly. That's what I was looking for. We're just gathering info to figure out how to proceed.

    Maybe my rumble is an anomaly. A bad egg and I was unlucky. A lot of owners seem to be unlucky with a very specific issue. But most owner's are in the happy customer category, so there's that.

    Sometimes you go a mechanic and he lets you know that he's seen your particular problem, on your particular model, on your particular model year before. Not indicative of all, but your take away is there's a spike and its not unheard of. Maybe you figure that he's a flat earther and decide to disregard. Or maybe you figure that he's got no reason to lie to you and that you're better off because he shared his experience.

    Good to know that your experience with these amps doesn't reflect mine. I'm a Fender fan and want the company to continue to thrive.
     
  12. agedhorse

    agedhorse Supporting Member Commercial User

    Feb 12, 2006
    Davis, CA (USA)
    Development Engineer-Mesa, Product Support-Genz Benz
    Im just stating my experience as I know it based on those I have seen.
     
    12Toes likes this.
  13. adk teleman

    adk teleman

    Aug 28, 2011
    Alex Bay NY
    I have a Rumble 150 v2 and it is rock solid! In fact I tried the v3 and hate it in comparison! No issues what so ever with it! It’s my go to small gig amp!
     

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