Results 1 to 7 of 7

Thread: M3 vibrato problem

  1. #1
    ppp Pianississmo scrimpus's Avatar
    Join Date
    Jul 2012
    Posts
    14

    M3 vibrato problem

    I just got an M3 and everything seems to be working except when I switch the vibrato on I get almost no sound at all, barely audible. The vibrato preamp is working and I have traced the signal to the scanner terminals but nothing on the scanner output. I have even swapped the scanner for another I had here with the exact same result. What could be doing this?

  2. #2
    mp Mezzo-Piano Jaim's Avatar
    Join Date
    Dec 2015
    Location
    Rogers, MN
    Posts
    386

    Vibrato signal out on preamp Term C to the delay line, switches / scanner and back in on Term D. Term D is where the dry signal, perc and pedal sum up so if that works, no problem there. What were you using to signal trace? With a key held down, you should see 3-4 VAC on the term C output going to the line box.

    Wonder if the shielded cable from the scanner to term D is ok. When you swapped the scanner, did you swap this as well?

    Jim

  3. #3
    ppp Pianississmo scrimpus's Avatar
    Join Date
    Jul 2012
    Posts
    14

    I have signal at C. signal at the line box and scanner but very, very weak signal getting back to D. I use a probe I built connected to a tiny bass combo amp to trace to audio signal. I wasn't able to replace the line from the scanner to D. as the donors line had been cut but I did test it for continuity and shorts to ground and it tested fine. I'll disconnect the line and test for signal directly out of the scanner at its output terminal to be sure as it had gotten so late I can't remember now if I had done that. dry signal is fine, switches are working and I really am not sure if the percussion is working yet.

  4. #4
    ppp Pianississmo scrimpus's Avatar
    Join Date
    Jul 2012
    Posts
    14

    Line tested fine, no signal at the scanner output terminal or center pin with the line disconnected, just a ghost of the vibrato effect is getting thru. No clue whats going on. Well after a re-cap and replacing a hand full of way out of spec resistors I now have vibrato and percussion and a lot more volume.
    Last edited by scrimpus; 09-14-2017 at 08:51 AM.

  5. #5
    mp Mezzo-Piano Jaim's Avatar
    Join Date
    Dec 2015
    Location
    Rogers, MN
    Posts
    386

    V2 Screen and plate Resistors?
    Jim

  6. #6
    pp Pianissimo organoman's Avatar
    Join Date
    Oct 2011
    Location
    Orygun
    Posts
    92

    Quote Originally Posted by scrimpus View Post
    I just got an M3 and everything seems to be working except when I switch the vibrato on I get almost no sound at all, barely audible. The vibrato preamp is working and I have traced the signal to the scanner terminals but nothing on the scanner output. I have even swapped the scanner for another I had here with the exact same result. What could be doing this?
    I know this is an old post, but I'm surprised at the replies to this query.
    There are two 6AU6 tubes in the amp. One is for Vibrato On, the other for Vibrato Off.
    If you swap the two 6UA6 tubes and the Vibrato ON/OFF results are opposite, the one of the 6AU6 tubes is bad.

    Been there, done that. Too simple.

  7. #7
    ff Fortissimo enor's Avatar
    Join Date
    Jan 2013
    Location
    Vargön, Sweden
    Posts
    2,053

    Well, as you see in post #4, the problem wasn't a tube and the problem is now fixed. Screen and/or plate resistor failure is far more common than tube failure.
    Current organs: BC, A-100, E-100
    Current Leslies: 22H, 142, 147, 760
    Organs in the past: L-100 (several), M-100 (x2), T-100, CV

Similar Threads

  1. Replies: 2
    Last Post: 05-02-2017, 05:21 PM
  2. M102 vibrato problem and internal speaker problem.
    By jim white in forum Hammond Organs
    Replies: 15
    Last Post: 02-03-2013, 11:14 PM
  3. CV vibrato problem
    By don celenza in forum Hammond Organs
    Replies: 2
    Last Post: 01-18-2010, 02:10 AM
  4. Replies: 10
    Last Post: 11-01-2009, 01:27 PM
  5. M3 Vibrato problem
    By disorganized in forum Electronic Organs
    Replies: 3
    Last Post: 07-02-2005, 11:08 AM

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
  •