Ampeg SVT-CL: No green bias

Discussion in 'Amps [BG]' started by Kaspergreenday, Dec 19, 2013.


  1. Kaspergreenday

    Kaspergreenday

    Joined:
    May 19, 2010
    I'm trying to sell my Ampeg-SVT, love the sound but im going for a more lightweight setup.

    The problem is, the bias lights can only show red. The green light wont go on when the red goes of, but i remember that the green light worked (only on one of the sides though) about a month ago.

    I searched a bit, and if i understand it correctly, it ussually works to change some tubes. Since im selling it, i wont bother changing tubes, as long as the amp is fine, but should i be worried? Should i let a tech check it out, or should i just remind buyer that it will most likely get fixed by changing tubes?

    Thanks in advance, Kasper.
  2. vbchaos

    vbchaos

    Joined:
    Sep 5, 2011
    Location:
    Groningen, The Netherlands
    Disclosures:
    Uncompensated endorsing user: fEARful
    I would at least contact a tech about it. I personally hate it to sell something that can cause problems afterwards - legally you are on the safe side (used markets usually are based on "bought as seen") but from a moral side of view I wouldn't feel well.
    I have sold an amp to a fellow here - it worked fine for 3 weeks and had problems from that moment. Not my problem but I didn't feel good about about. Luckily it was solved quickly.
  3. beans-on-toast

    beans-on-toast Supporting Member

    Joined:
    Aug 7, 2008
    Tough call. If you sell it with an issue, the buyer isn't going to pay the going rate since they will need to retube or perhaps pay to have some other issue fixed. The amp will be easier to sell if it has been checked out by a tech and is working. Either way it is going to cost you. I think that it is better to have it working when you sell it unless you are willing to knock down your asking price.

    Assuming the issue is the tubes, a tech can look at your power tubes and substitute a used one or more that matches the others and that might fix your issue so that it can be biased. Buying a new set of tubes will be a lot more expensive.
  4. Jim C

    Jim C Supporting Member

    Joined:
    Nov 29, 2008
    I'll go the other way.
    If the green led's worked, it sounded good, but there were other unknown problems you would be unaware and in the clear.
    If you were to try swapping or installing used tubes and the led's worked correctly, it sounds good, who says there are other problems.
    It's a used tube amp; is it your responsibility to have a tech go through and check something that is working properly?
    What about any components whose value have drifted beyond spec; should those all be changed?

    Make the bias lights work properly and sell the amp; if you can't do so with power tubes, then it is tech time. Swapping tubes will not hurt the amp anymore than it already is or is not.
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  6. Kaspergreenday

    Kaspergreenday

    Joined:
    May 19, 2010
    I havent got a spare set of power tubes, but i think i have spare driver/preamp tubes, should i bother trying to change them, is there any chance at all that this could be the fault?
  7. B-string

    B-string Supporting Member

    Joined:
    Nov 21, 2008
    Location:
    Lake Havasu City, Az USA
    Your call? Just me, I like things in the best possible working order when I sell. It is used equipment and anything can fail after it leaves you but if a tech checks it over and at least confirms it is weak output tubes you can provide the buyer with that diagnosis. You'll get a better sale than "I did this and it's all better." Not as good as with new tubes but better than "This seemed to work."?
  8. BassmanPaul

    BassmanPaul Gold Supporting Member

    Joined:
    Aug 25, 2007
    Location:
    Toronto Ontario Canada
    Karma is a strange thing and it can easily bite you in the butt. Get the amp looked at, repaired and when the buyer takes delivery, give him/her all the repair paper work. Thgis will make you feel better in the end (especially if Karma hasn't bitten it. :D ). IMHO of course.
  9. Clouz

    Clouz The Ayatollah of Jack and Cola Supporting Member

    Joined:
    Jan 26, 2013
    i had that happen on a brand new SVT Heritage after i unboxed it and played it for the first time. Ampeg told me that sometimes tubes are damaged in shipping and they sent me a new set of power tubes only. now both green lights are on. my one power tube had a white milky color at the top.
  10. Jim C

    Jim C Supporting Member

    Joined:
    Nov 29, 2008
    Totally agree about Karma, but doing the right thing was not the smartest thing in a very expensive divorce settlement.

    I bought a Trace Elliot head on this board years ago that had many of the output transistors cooked. The seller wouldn't commit to helping with repairs as he never knew it was in trouble and it sounded good at low volume.

    Same thing with an Acme cabinet that I bought here from a seller with decent feedback.
    Cost me $40 bucks to ship it back for a refund as the drivers were badly damaged,

    The no green light says the bias is out.
    If power tubes fix it, great; tell the buyer you put tubes in and now the bias lights work properly.

    When you sell a used car, do you have a mechanic check the oil pump or drop the pan to check main bearing clearances because it takes longer on start up for the oil light to go out?

    To the OP; it might be cheaper to sell it as it is depending on the tech bill and that would be straight up. Does it sound like an SVT should?
  11. MAMMOTHvolume

    MAMMOTHvolume

    Joined:
    Apr 29, 2009
    Location:
    sheffield, uk
    green light not turning on means one of the valves isn't pulling current
  12. tjconn

    tjconn

    Joined:
    Feb 24, 2014
    I have owned an AMPEG CL for years. Love it/hate it. It's in the shop a lot. I have the same issue with One of the Bias lights not lighting up. My tech checked the LED and it is fine. So it is not simply a bulb issue. Any help?

    Also from reading this thread I wanted to metion that you can't just throw an old set of tubes into these amps. They have to be a matched Sextet.

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