Results 1 to 8 of 8

Thread: AB763/6G16 Circuitry

  1. #1
    New Member
    Join Date
    Oct 2010
    Location
    Lakeland, FL
    Posts
    5
    Thumbs Up/Down
    Received: 0/0
    Given: 0/0
    Rep Power
    0

    AB763/6G16 Circuitry

    Hello there fellow amp kit builders, I need some assistance on the hook up wiring with an Indigo AB763/6G16 chassis board. I had no problems until I ran into the Vibrato speed cap section.

    I went to several sites and found the Vibroverb layout showing the Intensiy/Bias alteration and got that. V5 also has changes that was followed with one hangup.

    On the board the last pair of Cathode Bypass cap/resistor is 2.7k/25u which usually goes to V5-3 on the AB763 but in the 6G16 case goes to the 4.7k/25u/1M/.02 eyelet leaving the 2.7/25u junction open. It appears the signal stops there.

    I emailed Indigo Amps two weeks ago and Eric Z wasn't sure what I was talking about and he wanted any drawing I had so I sent them with no replies. So I stuck with project gathering dust on my bench.

    Thanks for reading this post. -Relayer

    0 Not allowed! Not allowed!

  2. #2
    Old Timer
    Join Date
    Jun 2006
    Posts
    3,315
    Thumbs Up/Down
    Received: 1/0
    Given: 0/0
    Rep Power
    17
    Which are you building? You can't mix & match because the 2 have different tremolo circuits. pin 8 of V5 in a 6G16 goes to the junction of 2x470K resistors. On the AB763 it connects to 100K bypassed with a 25/25 cap.

    On both amps only one of the last pair of bypassed cathode resistors connects to V5 pin 3, the other connects to V4

    0 Not allowed! Not allowed!

  3. #3
    New Member
    Join Date
    Oct 2010
    Location
    Lakeland, FL
    Posts
    5
    Thumbs Up/Down
    Received: 0/0
    Given: 0/0
    Rep Power
    0
    Thanks so much for your reply. It's great to have such knowledgeable people to answer questions.

    I have the eBay site below for clarification in which you can see what the board looks like.

    Deluxe, Twin Reverb Vibroverb AB763 Repro Circuit Board - eBay (item 120591470406 end time Oct-31-10 01:39:14 PDT)

    The three bypass cap/res are left of dead center in the larger image and the center bypass cap/res is the 2.7k/25u junction that would be left open when I connect V5-3 to 1M/25/4.7k eyelet to the left.

    On your statements, this is true on each layout. This layout is an AB763/6G16 mod. Just about everything is as a Deluxe Reverb with the exception of OptoIsolator circuit is replaced with the 6G16 circuit.

    Thanks again, Sir

    0 Not allowed! Not allowed!

  4. #4
    Old Timer
    Join Date
    Jun 2006
    Posts
    3,315
    Thumbs Up/Down
    Received: 1/0
    Given: 0/0
    Rep Power
    17
    Connect V5 pin 3 to the 4.7K/1 Meg junction to the right of that vertical line of little blue caps, leave the connection to the 2700 resistor, to it's right, open. The board appears to have an extra cap, probably why it's being sold with no support etc.

    0 Not allowed! Not allowed!

  5. #5
    New Member
    Join Date
    Oct 2010
    Location
    Lakeland, FL
    Posts
    5
    Thumbs Up/Down
    Received: 0/0
    Given: 0/0
    Rep Power
    0
    Thank you very much Sir, I appreciate the answer. I'm new to tube amp building and it's been the best hobby in the world for me. To put an amp together and gig is fantastic. People come from everywhere to ask how I get that beautiful full sound.

    Why would anybody leave that section in is beyond me and threw me for a loop.

    One more question, how does the signal get through that part of the circuit left open? To me it seems to stop at that juction.

    0 Not allowed! Not allowed!

  6. #6
    Old Timer
    Join Date
    Jun 2006
    Posts
    3,315
    Thumbs Up/Down
    Received: 1/0
    Given: 0/0
    Rep Power
    17
    It doesn't go anywhere, there is nothing to connect to it, no signal to apply to it. It's there to bias the tube, but, you have more components that you have tube pins to wire them t, so the tube (V5a) is being biased by the 4700 that you are using..

    0 Not allowed! Not allowed!

  7. #7
    New Member
    Join Date
    Oct 2010
    Location
    Lakeland, FL
    Posts
    5
    Thumbs Up/Down
    Received: 0/0
    Given: 0/0
    Rep Power
    0
    MMJB, your information got me up and running. Thanks so much for your help. You and Music-Electronic-Forum does more good than you know.

    At first the amp sounded very close to the two AB763 DRs I already have and I wanted a totally different flavor so I went to a drawing from Weber and spotted 6L6s. Swapped & biased and wow the amp exploded with this great clean sound. I A/B & blend for a wide array of genres.

    The funny thing is the 6G16 vibrato circuit isn't such a big deal, it works but there's not too many applications for it. The Mallory caps were a pleasant surprise. They do swing differently than Orange Drops. I'm feel great that with your help my project came through with flying colors.
    Take care, Steve

    0 Not allowed! Not allowed!

  8. #8
    New Member
    Join Date
    Oct 2010
    Location
    Lakeland, FL
    Posts
    5
    Thumbs Up/Down
    Received: 0/0
    Given: 0/0
    Rep Power
    0
    MMJB, your information got me up and running. Thanks so much for your help. You and Music-Electronic-Forum does more good than you know.

    At first the amp sounded very close to the two AB763 DRs I already have and I wanted a totally different flavor so I went to a drawing from Weber and spotted 6L6s. Swapped & biased and wow the amp exploded with this great clean sound. I A/B & blend for a wide array of genres.

    The funny thing is the 6G16 vibrato circuit isn't such a big deal, it works but there's not too many applications for it. The Mallory caps were a pleasant surprise. They do swing differently than Orange Drops. I'm feel great that with your help my project came through with flying colors.
    Take care, Steve

    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. Ab763 question
    By spufuz in forum Build Your Amp
    Replies: 17
    Last Post: 08-20-2010, 03:57 PM
  2. AB763 Trem
    By trem in forum Theory & Design
    Replies: 6
    Last Post: 06-25-2010, 02:51 AM
  3. Need Help with a 6G16 63 RI Vibroverb problem
    By Normybaby in forum Debugging Your Build
    Replies: 11
    Last Post: 01-11-2009, 02:22 AM
  4. 6G16 Vibroverb vibrato problem - red plating tubes!
    By Josh_B in forum Maintenance, Troubleshooting & Repair
    Replies: 10
    Last Post: 06-30-2008, 12:55 PM
  5. Showman AB763
    By Elfshimmer in forum Maintenance, Troubleshooting & Repair
    Replies: 8
    Last Post: 07-29-2007, 05:57 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
  •