Results 1 to 15 of 15

Thread: Frontman 15 just buzzes

  1. #1
    New Member
    Join Date
    Apr 2018
    Posts
    3
    Thumbs Up/Down
    Received: 0/0
    Given: 0/0

    Frontman 15 just buzzes

    Found a cheap amp for 20 bucks which worked fine for a couple of years .then all of a sudden the volume controls wouldn't work but you could control volume with guitar control so I took it apart and the normal volume, gain ,and drive volume pots had broken where the bakilite substright leaves the pot.found new ones and replaced them now the thing just has a load hum and nothing works .any one have any ideas what might be wrong

    0 Not allowed! Not allowed!

  2. #2
    Supporting Member The Dude's Avatar
    Join Date
    May 2010
    Location
    Sioux Falls, SD
    Posts
    5,159
    Thumbs Up/Down
    Received: 122/0
    Given: 103/0
    That could be any number of things. First, measure both AC and DC at the speaker output of the amp and let us know which it is. You could have a shorted output IC, bad or loose filter cap, etc., etc.

    0 Not allowed! Not allowed!
    “Yeah, well, you know, that’s just, like, your opinion, man.”

  3. #3
    Bent Member Chuck H's Avatar
    Join Date
    May 2007
    Location
    pacific north west
    Posts
    13,223
    Thumbs Up/Down
    Received: 184/0
    Given: 260/0
    Since the amp worked (fundamentally) before the work, I would suspect anything involved with the work. Connectors reconnected, any leads that were removed are returned to their proper location, stress to board pads causing failure, cold solder joints due to surface tension, etc.

    0 Not allowed! Not allowed!
    "I'm just going to perform a bit more scientific investigation, turn it up to 11 and rip of the knob." überfuzz

    "...less ear-friendly but handy for jazz." Leo_Gnardo

    "A pedal, any kind, will not make a Guitar player more dangerous than he already is." J M Fahey

    "If you build it, it will hum..." Justin Thomas

  4. #4
    don't forget the joker g1's Avatar
    Join Date
    Feb 2010
    Location
    Canada, somewhere north of Fargo
    Posts
    9,931
    Thumbs Up/Down
    Received: 130/0
    Given: 290/0
    Also, pots usually break like that when the amp does a face-plant. In most cases the input jack or related traces get damaged too.
    Did you look at the jack closely and inspect the circuit board for cracks?

    0 Not allowed! Not allowed!
    The voices in my head are idiots!

  5. #5
    Supporting Member
    Join Date
    Dec 2009
    Location
    UK
    Posts
    3,253
    Thumbs Up/Down
    Received: 18/0
    Given: 2/0
    My inclination is to think that in the process of replacing the pots something didn't get reconnected and left the signal path open. Re-check the solder pads and make sure one or more tracks aren't broken and that the joints are good.

    0 Not allowed! Not allowed!

  6. #6
    New Member
    Join Date
    Apr 2018
    Posts
    3
    Thumbs Up/Down
    Received: 0/0
    Given: 0/0

    Reply to chuck

    Quote Originally Posted by Chuck H View Post
    Since the amp worked (fundamentally) before the work, I would suspect anything involved with the work. Connectors reconnected, any leads that were removed are returned to their proper location, stress to board pads causing failure, cold solder joints due to surface tension, etc.
    checked all soldered joints had continuity at all points.board does not have any visual defects looks perfect .I've taken it apart and reassembled mutable times with same results

    0 Not allowed! Not allowed!

  7. #7
    New Member
    Join Date
    Apr 2018
    Posts
    3
    Thumbs Up/Down
    Received: 0/0
    Given: 0/0
    Would all the input jack solder joints be grounded

    0 Not allowed! Not allowed!

  8. #8
    Bent Member Chuck H's Avatar
    Join Date
    May 2007
    Location
    pacific north west
    Posts
    13,223
    Thumbs Up/Down
    Received: 184/0
    Given: 260/0
    Quote Originally Posted by John0007 View Post
    checked all soldered joints had continuity at all points.board does not have any visual defects looks perfect .I've taken it apart and reassembled mutable times with same results
    I'm only observing that the amp "worked" (the volume pot being ineffective was recognized and the reason for the repair) before you did repairs. Now it doesn't. The probability that something other than your work is causing this failure to produce sound seems remote. But it's not unheard of to have a peripheral failure happen at the exactly right moment to make you question your own repair. So it IS a possibility that it isn't your work. But that is still the most likely cause. Don't kill the messenger.

    0 Not allowed! Not allowed!
    "I'm just going to perform a bit more scientific investigation, turn it up to 11 and rip of the knob." überfuzz

    "...less ear-friendly but handy for jazz." Leo_Gnardo

    "A pedal, any kind, will not make a Guitar player more dangerous than he already is." J M Fahey

    "If you build it, it will hum..." Justin Thomas

  9. #9
    Bent Member Chuck H's Avatar
    Join Date
    May 2007
    Location
    pacific north west
    Posts
    13,223
    Thumbs Up/Down
    Received: 184/0
    Given: 260/0
    Quote Originally Posted by John0007 View Post
    Would all the input jack solder joints be grounded
    No schematic has been provided, but almost certainly no. If all the input jack solder joints were grounded then the input signal would be grounded and the amp wouldn't work like that. g1 is noting the construction of the amp. The input jacks actually act as supports for the board, relying on the solder connections and board pads. It can compromise the solder joints with even typical use stresses. The pots are actually floating on the board from what I can tell. They aren't even panel secured. That means any use of the pots puts stress on those solder joints because they are the only things holding the pots in place. These issues are very common failure modes for amps of this sort of construction.

    0 Not allowed! Not allowed!
    "I'm just going to perform a bit more scientific investigation, turn it up to 11 and rip of the knob." überfuzz

    "...less ear-friendly but handy for jazz." Leo_Gnardo

    "A pedal, any kind, will not make a Guitar player more dangerous than he already is." J M Fahey

    "If you build it, it will hum..." Justin Thomas

  10. #10
    Supporting Member Jazz P Bass's Avatar
    Join Date
    Dec 2008
    Location
    Wernersville, PA
    Posts
    12,243
    Thumbs Up/Down
    Received: 35/0
    Given: 15/0
    Quote Originally Posted by John0007 View Post
    Would all the input jack solder joints be grounded
    The only pin of the 9 pins of the input jack that is at ground potential is the sole lonesome one at the top.

    Here is a copy of the G & the R Frontman 15 service manual.

    Frontman 15G & 15R Mexico.zip

    0 Not allowed! Not allowed!

  11. #11
    Bent Member Chuck H's Avatar
    Join Date
    May 2007
    Location
    pacific north west
    Posts
    13,223
    Thumbs Up/Down
    Received: 184/0
    Given: 260/0
    Quote Originally Posted by Jazz P Bass View Post
    Here is a copy of the G & the R Frontman 15 service manual.
    It's absolutely GREAT that you're so good at, and vigilant with locating and posting the circuits in question on the forum. It's been an asset to be sure, but... Sometimes I think a man should arrange things for themselves if they wish to progress. I did look up the schem, but I was trying to encourage the OP to be proactive to an appropriate level of accountability on the matter. Which seems only right since (probably) none of us have a broken Frontman 15.

    0 Not allowed! Not allowed!
    "I'm just going to perform a bit more scientific investigation, turn it up to 11 and rip of the knob." überfuzz

    "...less ear-friendly but handy for jazz." Leo_Gnardo

    "A pedal, any kind, will not make a Guitar player more dangerous than he already is." J M Fahey

    "If you build it, it will hum..." Justin Thomas

  12. #12
    Supporting Member Jazz P Bass's Avatar
    Join Date
    Dec 2008
    Location
    Wernersville, PA
    Posts
    12,243
    Thumbs Up/Down
    Received: 35/0
    Given: 15/0
    "Which seems only right since (probably) none of us have a broken Frontman 15. "

    Actually, I do have one right in front of me.

    Click image for larger version. 

Name:	FM 15G.jpg 
Views:	27 
Size:	299.6 KB 
ID:	48375

    0 Not allowed! Not allowed!

  13. #13
    Bent Member Chuck H's Avatar
    Join Date
    May 2007
    Location
    pacific north west
    Posts
    13,223
    Thumbs Up/Down
    Received: 184/0
    Given: 260/0
    Quote Originally Posted by Jazz P Bass View Post
    Actually, I do have one right in front of me.
    Bowing and stepping backwards

    0 Not allowed! Not allowed!
    "I'm just going to perform a bit more scientific investigation, turn it up to 11 and rip of the knob." überfuzz

    "...less ear-friendly but handy for jazz." Leo_Gnardo

    "A pedal, any kind, will not make a Guitar player more dangerous than he already is." J M Fahey

    "If you build it, it will hum..." Justin Thomas

  14. #14
    don't forget the joker g1's Avatar
    Join Date
    Feb 2010
    Location
    Canada, somewhere north of Fargo
    Posts
    9,931
    Thumbs Up/Down
    Received: 130/0
    Given: 290/0
    Quote Originally Posted by John0007 View Post
    Would all the input jack solder joints be grounded
    It's possible they may measure like this if you have nothing plugged into the input jack. Plug a cord in there with nothing connected to the other end. Do all the jack contacts still read short to ground?

    0 Not allowed! Not allowed!
    The voices in my head are idiots!

  15. #15
    Supporting Member Jazz P Bass's Avatar
    Join Date
    Dec 2008
    Location
    Wernersville, PA
    Posts
    12,243
    Thumbs Up/Down
    Received: 35/0
    Given: 15/0
    Quote Originally Posted by g1 View Post
    It's possible they may measure like this if you have nothing plugged into the input jack. Plug a cord in there with nothing connected to the other end. Do all the jack contacts still read short to ground?
    I just checked the one that I have.

    With no input, the only ground connection is the top pin.

    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. Mesa Boogie TransAtlantic 15 TA-15 plate voltage
    By pecorporation in forum Maintenance, Troubleshooting & Repair
    Replies: 7
    Last Post: 02-08-2017, 11:45 PM
  2. Frontman 15 g buzzing
    By rach.wind. in forum Music Electronics
    Replies: 0
    Last Post: 04-04-2012, 02:19 AM
  3. my bass combo buzzes constantly. it must be a ground, but how can i fix it?
    By jimgunnz in forum Maintenance, Troubleshooting & Repair
    Replies: 3
    Last Post: 12-21-2011, 06:37 PM
  4. Squire Champ 15/Fender Frontman 15(R)
    By IDSkoT in forum Maintenance, Troubleshooting & Repair
    Replies: 8
    Last Post: 12-09-2009, 02:00 AM
  5. diy 6g3 buzzes
    By dwhutchens in forum Build Your Amp
    Replies: 19
    Last Post: 10-18-2008, 04:05 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
  •