Feedback from amp and stripped screws!

Discussion in 'Amps and Cabs [BG]' started by Angus, Oct 19, 2001.

  1. Angus

    Angus Supporting Member

    Apr 16, 2000
    Palo Alto, CA
    Well, I've got a bit of a situation on my hands.

    First topic...

    I've got an Ampeg SVT-4 Pro that I've had for maybe...a year? Well, as of today, it all the sudden in the middle of playing began to just feed back VERY loudly. I've tried replacing all the cords, and no matter, all it emits if this very loud buzzing sound. My only guess is that it's the pre-amp tubes that were shot...fairly surprising, as they should last FAR longer than a year! Anyone have any idea what it would be? Also, any ideas of the cost?


    Upon removing a rack drawer from my rack to put in something else, I noticed that two of the screws are stripped at the screwdriver insert...pretty much completely. The unit in there can't be removed as far as I've because of it. Anyone have any ideas about how to get it out? It's a two space unit, and (of course), the screws are kitty corner to each other. The lower one MIGHT be accessible from behind, but the upper definitely isn't. Any help would be greatly appreciated!

    Thanks!!! :):)
  2. I thought ampeg amps have very good warrenties, shouldn't it still be under warrenty if you only had it for a year?
  3. Captain Awesome

    Captain Awesome

    Apr 2, 2001
    The tubes themselves usually have only a 90 or so day warranty, cause they're likely to crap out sooner or later.
  4. Nightbass


    May 1, 2001
    Seattle, WA
    Are you saying that you have a two-space rack drawer that is stuck in the rack case because of a stripped screw? If so, you should be able to get the screw out if you push real hard on the back of the drawer (pushing it towards the front of the rack) *while* you are turning the stripped screw with a screwdriver. That will push against the head of the screw and force the good threads to engage the captive nut, and the screw will begin to come out normally. Just keep pushing until you are home free. This has worked for me many times. Good luck!

  5. Angus

    Angus Supporting Member

    Apr 16, 2000
    Palo Alto, CA
    Thanks for the responses!

    About the's not a TUBE amp, it's a hybrid with preamp tubes. Preamp tubes, IIRC, should last for a couple years.

    About the screws...they aren't stripped on the THREAD. They're stripped on the top of the screw, where the screw driver tip is inserted. If I just push on the back of the rack drawer, it will chance hurting the rack itself, which is NOT good! Make sense? I'm not sure what to do...
  6. CrawlingEye

    CrawlingEye Member

    Mar 20, 2001
    Easton, Pennsylvania
    If ^^^ doesn't work, you could try...

    Pulling the end of the screw out as far as you can, and cutting it with a bolt cutter.
  7. CrawlingEye

    CrawlingEye Member

    Mar 20, 2001
    Easton, Pennsylvania

    *lame-o response GO!*

    I recently saw a comercial on T.V. for a new craftsman tool, that's designed to get screws that are stripped at the head, out.
    You could check out your local Sears store.

    *lame-o response STOP!*
  8. HeavyDuty

    HeavyDuty Supporting Curmudgeon Staff Member Gold Supporting Member

    Jun 26, 2000
    Central Texas
    Grab on to the screw heads with vise-locks (a small pair works well for this). Set the adjustment screw as tight as possible, so the act of locking the pliers squooshes the screwheads oval. Then, just back the screws out like normal.

    Done it many times this way...

    Alternately, take a reinforced cut-off wheel in a Dremel and cut slot heads. Don't use a non-reinforced wheel!
  9. istaticl


    Nov 29, 2000
    Prescott, AZ
    I second the dremel. I have gotten many stripped screws out this way. Always works. Hope theres enough room to fit it in there.
  10. Angus

    Angus Supporting Member

    Apr 16, 2000
    Palo Alto, CA
    Considering I don't think we own a dremel [:eek:]. I'll have to try the vice/pliers for now, i'll try it in the morning and see how it goes. If not, I'll be taking a nice trip to the hardware store.

    Are there any screws anyone knows of that work well but are FAR stronger than the ones generally given for this? The screws I have, which came with my amp, are like putty.

    Thanks again! :)
  11. CrawlingEye

    CrawlingEye Member

    Mar 20, 2001
    Easton, Pennsylvania

    I'm certainly not a hardware expert. However, I'm fairly sure there's different grades of screws.
  12. Angus

    Angus Supporting Member

    Apr 16, 2000
    Palo Alto, CA
    I'm fairly sure there are, too, but I'm wondering if a better grade will provide any more protection from this happening again.
  13. rllefebv


    Oct 17, 2000
    Newberg, Oregon
    I ALWAYS use 10-32 Allen head bolts in a rack-mount. Much more durable and harder to strip. Plus, in the unfortunate instance where one does strip, there's a much better surface for gripping with the vise-grips :D

  14. Hey Angus,
    As rllefebv said, alllen (hex) head screws are the best for not stripping. I've been putting together and taking apart racks (pro audio) for 10 years and I've tried everything. Philips - terrible, Flat -worse, Robertson (square)-better but not great. The hex head ones strip far less, and like rllefebv said as well, if they do strip, there's a lot more to grab with your vise grips. If you can't get it out, try using a 1/8 or 3/16 hardened drill bit to drill through the center of the screw. It's a bit tricky, but it will work.

    PS. It's probably not the preamp tubes, they should last for years (I've got a '76 SVT with the original preamp tubes), unless the amp got a good jolt (ie dropped) when they were hot.
  15. Angus

    Angus Supporting Member

    Apr 16, 2000
    Palo Alto, CA
    Hex screws? Cool!!! I'll definitely look into those! I've got a nice big set of allen wrenchs which need to be used, too (which, of course, no longer has the correct size to adjust my bridges...:mad: ). Thanks!

    The drill sounds a bit scary, but I will try the vices for now, and if necessary, will go get the tool that crawling eye talked about...and some nice screws.

    About the amp, yeah, it seems weird to me too that it would be the preamp tubes, but the only other thing that it could be would be the power circuitry itself has something wrong. It has to be internal, as far as I can tell, because all the inputs are tightly screwed on, all the cables seem fine, etc etc. Guess I just need to take it in.
  16. mgood


    Sep 29, 2001
    Levelland, Texas
    I build lots of racks as an audio visual installer. The suggestion about drilling through the screw heads is a pain in the butt, but it's one I've had to resort to before. It works.

    In the future, whatever kind of rack screws you choose, use FOUR of them in each peice of gear. Get some of the nylon rack washers if the screws don't come with them. ALWAYS use the washers. It'll make it easier to get stuff out of the rack, as well as protect the face of your gear from scratches. Don't overtighten the screws. The gear is not going to jump out of your rack. I see that a lot. People go crazy with screwguns. Even if the clutch on the drill is set very low, if it's turning full speed when it gets to the end, it will most likely be too tight. I prefer to put them in with a screwdriver.
  17. Angus

    Angus Supporting Member

    Apr 16, 2000
    Palo Alto, CA
    Yeah mgood, I checked the racks we have in our mechanical room, and they used regular screws and washers for all the stuff in there (two 9 foot racks). However, they won't ever have to remove anything in there unless it's not working properly, so it's alright.

    Amen about overtightening!!!
  18. Hategear

    Hategear Workin' hard at hardly workin'.

    Apr 6, 2001
    Appleton, Swissconsin
    I just skimmed through this thread, so it may have been posted already, but you can get some "left-handed" drill bits (you may be able to purchase a single bit as well, rather than a whole set), put them in a drill, switch it to "reverse" and drill the screw heads. The bit should catch on the head and turn it right out. When you put the new screws in, put a dab of Locktite on the threads, or use a drop of clear nail polish and then screw them in just until they are snug. My dad always says, "There's snug and then there's broken." Oh yeah, as was already said, use a washer. ;) Good luck.