Results 1 to 6 of 6

Thread: Ampeg SVT-II (non-pro) craps out after a few minutes

  1. #1
    New Member
    Join Date
    Aug 2015
    Posts
    2
    Thumbs Up/Down
    Received: 0/0
    Given: 0/0
    Rep Power
    0

    Ampeg SVT-II (non-pro) craps out after a few minutes

    I love this amp and it sounds fantastic, for about 3 minutes and then it dies (sound gets squashed to nothing, amp keeps running). If I flip the Standby on and off it will keep working for a couple of minutes and then crap out again. I can plug into the Power Amp In input and it runs fine, so the problem must be in the preamp somewhere.

    As a side note that probably has nothing to do with the main problem, the best I can do with the bias controls for voltage between TP1 and TP2 is -0.035V, when the instructions say to get +/- 0.01V.

    Any ideas?

    edit: schematics found here: https://www.dropbox.com/sh/wdcfkjkly...RxNlrUfRa?dl=0

    0 Not allowed! Not allowed!
    Last edited by vercingetorix; 08-05-2015 at 01:26 AM.

  2. #2
    Supporting Member Jazz P Bass's Avatar
    Join Date
    Dec 2008
    Location
    Wernersville, PA
    Posts
    12,921
    Thumbs Up/Down
    Received: 521/3
    Given: 275/0
    Rep Power
    26
    Post a schematic?

    0 Not allowed! Not allowed!

  3. #3
    New Member
    Join Date
    Aug 2015
    Posts
    2
    Thumbs Up/Down
    Received: 0/0
    Given: 0/0
    Rep Power
    0
    Quote Originally Posted by Jazz P Bass View Post
    Post a schematic?
    https://www.dropbox.com/sh/wdcfkjkly...RxNlrUfRa?dl=0

    0 Not allowed! Not allowed!

  4. #4
    Supporting Member nevetslab's Avatar
    Join Date
    Apr 2010
    Location
    Burbank, CA
    Posts
    1,791
    Thumbs Up/Down
    Received: 647/1
    Given: 1,475/1
    Rep Power
    11
    I'd take a look at C16...1uF electrolytic cap, from the cathode follower of the last preamp tube stage that goes out the ribbon cable header, passed thru the preamp output/power amp input jack. All the other coupling caps are film or maybe paper dielectric. If you have a scope, you could follow the signal thru the preamp and see where you begin to lose it. Could also be at the Graphic EQ, which follows this cap...but you do have an EQ in/out switch.


    C16.....10uF/16V. My SVT II schematic was a bit blurred, Jazz P Bass' s schematics cleared that up.

    0 Not allowed! Not allowed!
    Last edited by nevetslab; 08-06-2015 at 05:12 PM.
    Logic is an organized way of going wrong with confidence

  5. #5
    Don't forget the joker g1's Avatar
    Join Date
    Feb 2010
    Location
    Canada, somewhere north of Fargo
    Posts
    11,739
    Thumbs Up/Down
    Received: 1,607/23
    Given: 4,112/11
    Rep Power
    22
    That link is for the owners manual, not a schematic.

    0 Not allowed! Not allowed!
    Just because they don't have tubes doesn't mean they don't have feelings! - glebert

  6. #6
    Supporting Member Jazz P Bass's Avatar
    Join Date
    Dec 2008
    Location
    Wernersville, PA
    Posts
    12,921
    Thumbs Up/Down
    Received: 521/3
    Given: 275/0
    Rep Power
    26

    0 Not allowed! Not allowed!

Thread Information

Users Browsing this Thread

There are currently 1 users browsing this thread. (0 members and 1 guests)

Similar Threads

  1. Ampeg SVT-II Loud Hum
    By spforster in forum Maintenance, Troubleshooting & Repair
    Replies: 8
    Last Post: 06-13-2014, 10:59 PM
  2. SLM AMPEG SVT-II Pro
    By shiner555 in forum Maintenance, Troubleshooting & Repair
    Replies: 8
    Last Post: 01-22-2014, 05:23 PM
  3. Need help with SVT II Pro
    By Roberto Lasco in forum Maintenance, Troubleshooting & Repair
    Replies: 6
    Last Post: 08-19-2010, 06:47 PM
  4. Ampeg SVT II Pro - help needed
    By Roberto Lasco in forum Maintenance, Troubleshooting & Repair
    Replies: 5
    Last Post: 01-08-2010, 05:12 PM
  5. Ampeg SVT-II Bias Procedure
    By 52 Bill in forum Maintenance, Troubleshooting & Repair
    Replies: 0
    Last Post: 02-19-2008, 11:24 PM

Tags for this Thread

Bookmarks

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •