ampeg svt capacitor question

Discussion in 'Amps and Cabs [BG]' started by notforrobots, Jan 23, 2009.

  1. Frid

    Frid

    Apr 16, 2009
    Thanks for your fast replies, I'll clip off cap and wires to have that switch free of any current.Great forum btw!
    Frid
     
  2. matskull

    matskull

    Jun 5, 2006
    montreal
    I don't know if it has anything to do with my recap or if it's something else but I've got a little problem with my amp.

    When I switched it on today the standby switch wasn't working anymore, the sound was coming out of the speaker even though the standby was set to standby, it was also coming out if the switch was set to on.

    Then some times later I tried it again and this time it worked...

    Also, when the volume on my bass if rolled off or if there's nothing plugged into my amp I can hear some little pops and stuff like that, it comes out of the speakers.

    Does it sound like a bad switch to you or maybe a power tube?
    Even though a power tube wouldn't explain why the switch wasn't working, maybe I should try to clean it with some De-ox-it.
     
  3. BassmanPaul

    BassmanPaul Inactive

    Replace the standby switch. The contacts have probably welded closed.

    Paul
     
  4. matskull

    matskull

    Jun 5, 2006
    montreal
    That's what I thought.
    Thanks

    Any other thoughts about this?
     
  5. B-string

    B-string Supporting Member

    What model? Does it have a stanby circuit w/relay or just the switch?
     
  6. matskull

    matskull

    Jun 5, 2006
    montreal
    it's a vintage svt (1978)
    I'm not sure what kind of switch it is.
     
  7. johnk_10

    johnk_10 vintage bass nut Supporting Member Commercial User

    Feb 16, 2008
    Washington, Utah
    John K Custom Basses
    you need a heavy duty spst switch for your standby. its very common for them to stay on, stay off or become intermittent in either direction, so just replace it. i'd recommend one that can handle at least 15 amps @120VAC.
     
  8. B-string

    B-string Supporting Member

    My memory is fuzzy if that would be a Magnavox or M.T.I. era but I believe BassmanPaul has your answer. It should only have that mechanical switch for high voltage standby. 600 volt rated switch minimum, 115 volt switches will fail.
    JohnK 10 can also confirm for you.

    JohnK 10 was faster than I :) I do believe the 600 volt stanby switches are still avalible though
     
  9. matskull

    matskull

    Jun 5, 2006
    montreal
    Ok thanks guys, I won't be able to replace it right now because I kind of lost half of my job, I was full time and now I'm on call for a while which totally sucks.
    I'm thinking about going back to school but anyway...

    So it's not a super good idea to spend my money on that kind of stuff right now (I've got some bills to pay), do you think it can be harmful for the amp if I leave it like that for now?
     
  10. B-string

    B-string Supporting Member

    That is hard to say, you may already have a loss of high voltage from the switch?
    It may continue to be intermittant.
    It may fail open (amp won't work).
    It may fail closed (unknown if it is adding resistance to the high voltage circuit).
    It may short out (sparks and maybe blown fuse) usually a disturbing light show but no major damage.
     
  11. matskull

    matskull

    Jun 5, 2006
    montreal
    I see, thanks.
    At least I don't use it too much, 2-3 hours per week maybe.

    I guess if a switch is something like 10$ or so it's better than having to repair the whole amp because the switch made it break or something.

    I looked at fliptops but didn't find it there, where can I find such a switch?
     
  12. B-string

    B-string Supporting Member

    I'm sorry, I'll try to source it for you,, I'm still LMAO over suck a switch. I think thomas Organ used those in US made VOX. I'm sure you mean to type such, but my sides are killing me....

    I've found this one so far :http://www.mojomusicalsupply.com/item.asp?pid=580324&pg=13797&id=1400008 meets johnK 10's specs.
     
  13. matskull

    matskull

    Jun 5, 2006
    montreal
    haha, yeah I meant such.

    thanks for the help
     
  14. johnk_10

    johnk_10 vintage bass nut Supporting Member Commercial User

    Feb 16, 2008
    Washington, Utah
    John K Custom Basses
    yeah, that one will work fine. i try to find them with the shortest bat handle that i can so it doesn't protrude on the back of the head.

    i would highly recommend that you replace it asap. if its stuck in the on position, you're not allowing the the tubes to warm up before applying the high voltage- which will shorten the life of your output tubes (not cheap).
     
  15. matskull

    matskull

    Jun 5, 2006
    montreal
    Is there any recommended brand for the switch, cause I'd rather pick one up locally cause I don't wanna pay for shipping just for a switch, I'm in canada.

    I searched for a 600V and they don't seem very popular.
     
  16. RickenBoogie

    RickenBoogie

    Jul 22, 2007
    Dallas, TX
    The shipping will be alot less than the cost of replacing 6 big honkin' tubes, bro. Just sayin'.
     
  17. matskull

    matskull

    Jun 5, 2006
    montreal
    Yeah I know but there's a couple of electronic store in my area so if I could know what brank to look at I could buy it locally instead.
     
  18. Just a question from a rookie. After examining these two pics.. The top original photo shows the large orange cap on the right/center of the photo with glue ooze on the end.. the wire comes off and looks like it goes to R48. But in the "recapped" photo, it shows the pink wire coming off the new cap going to D5..

    Am I looking at that correctly?
     
  19. Jerrold Tiers

    Jerrold Tiers

    Nov 14, 2003
    St Louis
    Just for the record, the switches switch ONLY ordinary 120/240VAC, not the 600V. The amperage rating is more important than the voltage rating. Actually, the most important is the "inrush" rating...... but that number is not often available.

    There is no need for a 600V switch, but the switch should be rated at least 10A, preferably 15A, and voltage preferably 240V, unless your unit can be wired only for 120, in which case a 120V switch is OK..
     
  20. B-string

    B-string Supporting Member

    Thanks Jerrold.