Results 1 to 2 of 2

Thread: 65 Reissue Fender Twin Reverb returns with same explosive noises

  1. #1
    Senior Member nevetslab's Avatar
    Join Date
    Apr 2010
    Location
    Burbank, CA
    Posts
    1,493
    Thumbs Up/Down
    Received: 473/1
    Given: 1,149/1
    Rep Power
    11

    65 Reissue Fender Twin Reverb returns with same explosive noises

    As I keep a through service log on all of my repairs, another of our many Fender 65 reissue Twin Reverbs came in with ugly noises in use. Explosive is more the word, as if you bump it or hit it on it's top, it will bark at you, often very loudly! I didn't catch this until I had already gone thru all of the controls, initially just listening to residual noise, then with burst pink noise. Turning down the Normal Ch somehow initialized an unwelcome response, hinting at microphonic tube or something. I tapped on V1, which barked, did same on V2 and all the way down the row, coming to the driver V6, which tapping on that caused it to bark loudly!

    I pulled V6 tube out, once I had it in S/B to inspect the tube. The pins were dark, well oxidized. I brought it to the other bench to use the brass bristle brush, but that didn't change much. I then used an X-Acto blade to scrape away the oxidation and expose shiny tin plating. Brushed it some more, then plugged it back in. Much better.....almost thought I had found the culprit. Played with the amp a bit more, hearing tube noise in the Normal Ch. While swapping V4 with V1, I noticed the reflection of the heater in the mica washer inside made that tube glow a lot brighter than the others, and ended up swapping it with a new J/J ECC83S. Seemed ok. For a moment. Pounding on the top of the cabinet revealed otherwise.

    Went thru the power tubes, one by one, wire-brushing the pins, plugging them back in. Still had the same issue. I finally pulled the chassis out, landing it on the service cradle, and saw evidence of recent service by myself inside. Looked up the Asset number in my database, found it had 5 hrs of service just this past March....barely 2 months ago. I pulled up that record, found it was doing similar things then, though what was most objectionable with it then was the input jacks. Nudge the stock Fender jacks a bit, and it would bark loudly. I had posted a thread on those stupid jacks, finally getting it tame.

    Obviously not. So, I turned the chassis over, to open up the doghouse, after first discharging all of the supply filters. Once I had the dog house cover off, PCB removed and turned over, I saw obvious solder fractures on the main filter cap leads, as well as on the pair of 22uF supply cap leads. Lead Free solder. My Pace SX-70 Desoldering Iron has no luck with that stuff, even cranked up to 850-900 deg F. Back to solder braid, sucked the joints free of that stuff, pulled the leads down a bit more so I could fold the leads over (not done that way at the factory). Soldered those back up, cleaned up, put it back together, turned the chassis back over to give a listen again.

    Just lifting the preamp end of the chassis up an inch off the cradle and let it drop back down set it off, this time not using the speaker, but coupled to my analyzer/dummy load/scope to watch the behavior. Nasty results...set it off into a flurry of noise that never stopped without further prodding. OK.........if that's what I found in the doghouse, I now know the main PCB has to get lifted up. Sigh.........

    Disconnected all the xfmr leads, everything off the front side of the long board, removed the hardware, spun the chassis around so I'd be facing the front, and lifted the PCB up, carefully folding it over to give full access to the solder side.

    Solder fractures on EVERY tube lead of the first 3 tubes V1-V3, on half of the remainder, on the plate resistors of the driver tube, on the grid coupling caps between the power tubes and driver stage plates, etc. Lead Free solder! Don't ya just love that stuff??!!!!

    So, after getting all of that back to normal, it was time for a break, and to sit down to write this up, hoping I've nailed it this time. Still have to put it back together to find out.

    0 Not allowed! Not allowed!
    Logic is an organized way of going wrong with confidence

  2. #2
    Senior Member nevetslab's Avatar
    Join Date
    Apr 2010
    Location
    Burbank, CA
    Posts
    1,493
    Thumbs Up/Down
    Received: 473/1
    Given: 1,149/1
    Rep Power
    11
    Powered back up, while still in the service cradle. Now, lifting up the preamp end of the chassis an inch or so, letting it drop back down just generates the immediate transient, while not exciting anything else, the way it was doing. Pounded on the chassis, tapped on the tubes aggressively, all normal. Put it back into the cabinet, and powered it up, pounded on the cabinet, and now, finally, rock solid.

    The frightening thought is how many of the 65 reissues we have of that particular manufacturing date.

    0 Not allowed! Not allowed!
    Logic is an organized way of going wrong with confidence

Thread Information

Users Browsing this Thread

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

Similar Threads

  1. Fender Twin Reverb Reissue vibrato
    By sorin65 in forum Mods & Tweaks
    Replies: 8
    Last Post: 01-09-2018, 03:46 PM
  2. Fender red knob twin vs Fender twin reverb 65 reissue clean channel with Les Paul
    By jalexquijano in forum Maintenance, Troubleshooting & Repair
    Replies: 3
    Last Post: 11-20-2017, 03:34 AM
  3. 65 Fender Twin Reissue - No Reverb
    By tommyg in forum Maintenance, Troubleshooting & Repair
    Replies: 23
    Last Post: 12-21-2011, 05:10 AM
  4. Fender Twin Reverb Reissue distorted reverb
    By gromrock in forum Maintenance, Troubleshooting & Repair
    Replies: 21
    Last Post: 03-19-2011, 11:36 PM
  5. Fender 65 twin reverb reissue mods
    By j_man1974 in forum Mods & Tweaks
    Replies: 3
    Last Post: 03-31-2009, 12:30 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
  •