1. Win a Broadcaster or one of 3 Teles! The annual Supporting Member Giveaway is on. To enter Click Here. To see all the prizes and full details Click Here. To view the thread about the giveaway Click Here.

Help with Fender Reverb Unit (Reissue)

Discussion in 'Amp Tech Center' started by WineCaster, Mar 22, 2019.

  1. WineCaster

    WineCaster Tele-Holic

    Posts:
    532
    Joined:
    Jul 12, 2012
    Location:
    Oshkosh, Wisconsin
    Hey folks!

    I bought a Fender Reverb Unit (90's Reissue) on eBay. The seller said he couldn't get a reverb signal to pass through so I asked for a small refund and to send the unit as-is. I got it today and have been playing around with it to try and get to the bottom of the issue.

    The Problem:
    The unit passes dry guitar signal only. I can give the unit a smack and will hear "the splash" but that's it.

    What I've tried:
    • DeOxit on the pots and contact cleaner on the RCA jacks, Tube pins/sockets, and all mono jacks.
    • Different 1/4'' cables
    • Different tubes
    • Different RCA cables
    • Different Reverb tank
    • Testing the Unit's cables and tank in a different amp (worked fine)
    The only thing that I can possibly think of would be that the electrolytic caps are outside of their useful life as this is an early 90s reissue...

    What do you think?
     

    Attached Files:

  2. charlie chitlin

    charlie chitlin Doctor of Teleocity Silver Supporter

    Age:
    59
    Posts:
    15,692
    Joined:
    Mar 17, 2003
    Location:
    Kimberton
    If that's all you can think of, you had best send it to a tech.
     
  3. WineCaster

    WineCaster Tele-Holic

    Posts:
    532
    Joined:
    Jul 12, 2012
    Location:
    Oshkosh, Wisconsin
    Thanks for that.

    The helpful members of this forum and guided me through many safe and successful amp repairs and modifications. I'm enjoying the learning process and hoping for it to continue and not just ditch my problems and money on a tech. This PCB construction is going to have me asking for help before I start messing with this tight and/or fragile circuitry in hopes that someone can point me in the right direction.
     
  4. schmee

    schmee Doctor of Teleocity Silver Supporter

    Posts:
    12,584
    Joined:
    Jun 2, 2003
    Location:
    northwest
    Get the board out, turn it over and look for holes/bad flow in the solder points. There were a bunch of defective ones cheap on Ebay 10 years ago or so. The turret board is dead simple on the vintage units. make yours one! Trash the printed board and build a new board! I built a couple 10 years ago or so from Weber kits. Not sure if they still sell the board or not.
    [​IMG]
     
    Last edited: Mar 22, 2019
    robrob and WineCaster like this.
  5. Snfoilhat

    Snfoilhat Tele-Afflicted

    Age:
    39
    Posts:
    1,396
    Joined:
    Apr 8, 2016
    Location:
    Oakland, CA
    Reaching for the very lowest hanging fruit: have you unplugged the footswitch? Is that the black, L-style plug I see under the chassis? This is a type of effect where any short in the cable or switch turns the reverb off.

    Hanging quite a bit higher: test the voltage across that large 2W 1000 ohm resistor and we can see how well the 6V6 driver tube is working. But if you are willing to go that far, you can do a full workup of all the voltages and check them against the '63 reissue schematic.
     

    Attached Files:

    robrob, WineCaster and Sean Mac like this.
  6. kubiakl

    kubiakl Tele-Meister

    Posts:
    370
    Joined:
    May 9, 2012
    Location:
    Austin, TX
    I had a similar problem with a reverb unit (a '98 Kendrick reverb tank). By similar I mean pretty much the exact same - tried different cables, different tubes, dry signal only...

    The problem turned out to be the reverb transformer. (Maybe that's the "output transformer"? I looked at a parts list and there were three transformers, I don't know enough to know which is which. Sorry!) Had a fella replace that and it's been great.

    Not saying that's definitely the same problem you have and these other guys that posted clearly know more than I do about what to test, but it's what happened to mine with similar symptoms.
     
    Milspec and WineCaster like this.
  7. Sean Mac

    Sean Mac Tele-Meister

    Posts:
    198
    Joined:
    Mar 2, 2016
    Location:
    Dublin. Ireland.
    The reverb driver transformer is 8 ohms output.

    Try a speaker on the reverb send.
     
    Mr Ridesglide and clintj like this.
  8. clintj

    clintj Friend of Leo's

    Posts:
    4,957
    Joined:
    Apr 4, 2015
    Location:
    Idaho
    Do you have a DIY signal tracer or any other test gear? Shouldn't be too hard to walk the signal path from input jack to reverb send jack with one.

    I'd still get out the multimeter and start with verifying DC voltages at the various test points, though. That'll often raise a red flag before the more sophisticated tools come out to play.

    Sent from my Pixel 2 using Tapatalk
     
    WineCaster likes this.
  9. Papa Joe

    Papa Joe Friend of Leo's Silver Supporter

    Age:
    91
    Posts:
    4,232
    Joined:
    Jun 30, 2007
    Location:
    Swanton Ohio
    Did you check the connections on the tank ???
     
  10. WineCaster

    WineCaster Tele-Holic

    Posts:
    532
    Joined:
    Jul 12, 2012
    Location:
    Oshkosh, Wisconsin
    I’ve had terrible luck with reverb transformers going bad so maybe I’ll start with the reverb output transformer and see where it goes from there.
     
  11. corliss1

    corliss1 Friend of Leo's Platinum Supporter

    Posts:
    4,449
    Joined:
    Sep 13, 2008
    Location:
    Lansing, MI
    So..you've already isolated the problem and just don't realize it. If you hear the splash when you rattle the tank the reverb recovery is working. This means:

    -signal is not getting to the reverb pan
    or
    -input to the reverb is bad

    There's very few parts left in that area to chase. A signal tracer or swapping the reverb pan would identify that issue in about 5 minutes :D
     
    schmee likes this.
  12. robrob

    robrob Poster Extraordinaire Ad Free Member

    Posts:
    7,954
    Joined:
    Dec 29, 2012
    Location:
    United States
    Measure the voltages of V2 (12AT7) and V3 (6K6GT) and compare to this schematic. If they look good then it's probably the reverb transformer since you said you tried new tubes.
    [​IMG]
     
    WineCaster likes this.
  13. Ten Over

    Ten Over Tele-Holic

    Posts:
    666
    Joined:
    May 13, 2015
    Location:
    Central California
    This may be of use.
     

    Attached Files:

    WineCaster likes this.
  14. WineCaster

    WineCaster Tele-Holic

    Posts:
    532
    Joined:
    Jul 12, 2012
    Location:
    Oshkosh, Wisconsin
    I replaced the output transformer. Now a tiny pit of gritty(ish) reverb passes through the signal but still not nearly enough.
     
  15. robrob

    robrob Poster Extraordinaire Ad Free Member

    Posts:
    7,954
    Joined:
    Dec 29, 2012
    Location:
    United States
  16. WineCaster

    WineCaster Tele-Holic

    Posts:
    532
    Joined:
    Jul 12, 2012
    Location:
    Oshkosh, Wisconsin
    Solved:

    Welp. What is life if not a learning experience? I replaced the output transformer ($50) and all electrolytic caps ($25) to find the problem never changed. Then I re-flowed every solder joint. Nothin. So I tested the unit again with my DRRI tank and it was working! I don't know if I overlooked this in the initial testing (doh!) or if something I did actually was needed.

    Tuuuuurns out the reverb tank springs were pressed up against a foam pad mounted to the front of the cabinet. So this whole time they were pinned up and not able to move. I found that the reverb tank was aftermarket and meant to be mounted horizontally and I'm assuming there was at one point a cardboard slab between the foam pad and the tank.

    So I've got a new vertical mount tank on the way for $25. I'm not butt-hurt about replacing the caps as they were probably getting about due, but the transformer is kinda a burn. Anyway. Thanks again to everyone on this forum for their help!
     

    Attached Files:

    Paul in Colorado likes this.
  17. Milspec

    Milspec Poster Extraordinaire Silver Supporter

    Posts:
    5,296
    Joined:
    Feb 15, 2016
    Location:
    Nebraska
    Didnn't that unit use a foam pad for when transporting the unit in order to protect the springs? Sounds like the seller really screwed himself by not realizing that.
     
  18. kubiakl

    kubiakl Tele-Meister

    Posts:
    370
    Joined:
    May 9, 2012
    Location:
    Austin, TX
    Ah man, sorry you had to go through all that for something that wound up being a simple fix. I thought you had tried it with a different tank though?

    At any rate, glad it's fixed because there's something magical about those reverb units.
    :)
     
  19. schmee

    schmee Doctor of Teleocity Silver Supporter

    Posts:
    12,584
    Joined:
    Jun 2, 2003
    Location:
    northwest
    The shipping foam pads were in it? hahahahaha
    BTW, vertical or horizontal they work fine.
     
  20. corliss1

    corliss1 Friend of Leo's Platinum Supporter

    Posts:
    4,449
    Joined:
    Sep 13, 2008
    Location:
    Lansing, MI
    Do the reissues not use the little spring to lock the pan during transport? Not sure I've seen a rear shot of a reissue.
     
    Bill Moore likes this.
IMPORTANT: Treat everyone here with respect, no matter how difficult!
No sex, drug, political, religion or hate discussion permitted here.