Results 1 to 9 of 9

Thread: Blues Deluxe Noise Issue

  1. #1
    Senior Member
    Join Date
    Jun 2017
    Location
    Ontario, Canada
    Posts
    353
    Thumbs Up/Down
    Received: 23/0
    Given: 38/0
    Rep Power
    3

    Blues Deluxe Noise Issue

    I have a Fender Blues Deluxe (original, not BDRI) with an unusual problem. When adjusting the volume there is a scratchy sound but it is not due to dirty pots (have cleaned and even replaced the Master pot). On the normal channel it is almost inaudible but I can hear it. It is very noticeable on the drive channel particularly with the Drive pot set for high gain. In this case any movement of the pot at any point in its range causes the noise. Since it seems to also happen on the normal volume (albeit to a lesser degree) I was thinking PI or power amp. For simple troubleshooting I swapped out all the tubes but there was no change. I don't know where to look next. Thoughts anyone?

    Fender-Blues-Deluxe-Schematic.pdf

    0 Not allowed! Not allowed!

  2. #2
    Supporting Member
    Join Date
    Mar 2018
    Location
    Germany
    Posts
    2,085
    Thumbs Up/Down
    Received: 1,579/1
    Given: 893/2
    Rep Power
    5
    Are you speaking of R7? Check for DC on the pot.

    1 Not allowed! Not allowed!
    - Own Opinions Only -

  3. #3
    Lifetime Member Enzo's Avatar
    Join Date
    May 2006
    Location
    Lansing, Michigan, USA
    Posts
    31,875
    Thumbs Up/Down
    Received: 1,729/7
    Given: 0/0
    Rep Power
    54
    I was thinking PI or power amp.
    How would those stages know when you turned the control? I'm with Helmholtz, check for stray DC voltage on the noisy control. DC on a pot makes them noisy.

    You need to be aware there is only one channel through the amp. The "channels" you can switch between are really just gain changers switching in and out of the one channel.

    1 Not allowed! Not allowed!
    Education is what you're left with after you have forgotten what you have learned.

  4. #4
    Senior Member
    Join Date
    Jun 2017
    Location
    Ontario, Canada
    Posts
    353
    Thumbs Up/Down
    Received: 23/0
    Given: 38/0
    Rep Power
    3
    Quote Originally Posted by Helmholtz View Post
    Are you speaking of R7? Check for DC on the pot.

    More R21 than R7.

    Are you alluding to the possibility of a leaky coupling cap at C9 ? (and C2 if I'm actually hearing the same thing on the normal volume, its hard to know for sure)

    0 Not allowed! Not allowed!

  5. #5
    Lifetime Member Enzo's Avatar
    Join Date
    May 2006
    Location
    Lansing, Michigan, USA
    Posts
    31,875
    Thumbs Up/Down
    Received: 1,729/7
    Given: 0/0
    Rep Power
    54
    Voltage is just a possibility. The thing to do is just measure for it. If we find it, we can figure out why it is there. If there is no voltage, then there is no voltage to explain. And we move on.

    0 Not allowed! Not allowed!
    Education is what you're left with after you have forgotten what you have learned.

  6. #6
    Supporting Member
    Join Date
    Mar 2018
    Location
    Germany
    Posts
    2,085
    Thumbs Up/Down
    Received: 1,579/1
    Given: 893/2
    Rep Power
    5
    R21 would be the master pot. Whatever, check for DC across the scratchy pot(s). And yes, the usual suspects would be the plate coupling caps because the tube plates carry high DCV.

    0 Not allowed! Not allowed!
    Last edited by Helmholtz; 10-12-2019 at 05:55 PM.
    - Own Opinions Only -

  7. #7
    Senior Member
    Join Date
    Jun 2017
    Location
    Ontario, Canada
    Posts
    353
    Thumbs Up/Down
    Received: 23/0
    Given: 38/0
    Rep Power
    3
    Quote Originally Posted by Enzo View Post
    Voltage is just a possibility. The thing to do is just measure for it. If we find it, we can figure out why it is there. If there is no voltage, then there is no voltage to explain. And we move on.
    Cool, I'll check it out when I'll check it out when I get a chance.

    0 Not allowed! Not allowed!

  8. #8
    Senior Member
    Join Date
    Jun 2017
    Location
    Ontario, Canada
    Posts
    353
    Thumbs Up/Down
    Received: 23/0
    Given: 38/0
    Rep Power
    3
    Quote Originally Posted by Helmholtz View Post
    R21 would be the common master pot.
    Not on this amp. They call it Master but it is only for the lead channel.

    0 Not allowed! Not allowed!

  9. #9
    Supporting Member
    Join Date
    Mar 2018
    Location
    Germany
    Posts
    2,085
    Thumbs Up/Down
    Received: 1,579/1
    Given: 893/2
    Rep Power
    5
    Quote Originally Posted by bobloblaws View Post
    Not on this amp. They call it Master but it is only for the lead channel.
    I see, the relay takes it out of circuit in clean mode. Forget "common".

    0 Not allowed! Not allowed!
    - Own Opinions Only -

Thread Information

Users Browsing this Thread

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

Similar Threads

  1. Fender Blues Deluxe reverb issue HELP ! I'm going insane here !!
    By WillyK in forum Maintenance, Troubleshooting & Repair
    Replies: 10
    Last Post: 12-13-2017, 02:31 AM
  2. Fender Blues Deluxe Reissue channel switching issue.
    By jvm in forum Maintenance, Troubleshooting & Repair
    Replies: 10
    Last Post: 09-29-2016, 04:00 PM
  3. Fender Blues Deluxe Reissue clean channel Noise.
    By seeemilyplay in forum Maintenance, Troubleshooting & Repair
    Replies: 4
    Last Post: 12-01-2013, 01:19 AM
  4. Black Face Deluxe Reverb noise issue
    By bnwitt in forum Maintenance, Troubleshooting & Repair
    Replies: 10
    Last Post: 09-19-2010, 07:28 PM
  5. Fender Deluxe Reverb Re-Issue High Frequency Noise
    By jordankersten in forum Maintenance, Troubleshooting & Repair
    Replies: 2
    Last Post: 12-23-2008, 08:45 PM

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
  •