noise after fixing guitar amp? - diyAudio
Go Back   Home > Forums > Amplifiers > Solid State

Solid State Talk all about solid state amplification.

Please consider donating to help us continue to serve you.

Ads on/off / Custom Title / More PMs / More album space / Advanced printing & mass image saving
Reply
 
Thread Tools Search this Thread
Old 25th April 2005, 07:05 PM   #1
diyAudio Member
 
Join Date: Apr 2005
Location: scotland
Default noise after fixing guitar amp?

Hi,i bought a small Fender guitar amp at a car boot sale,i was told it was perfect,as new,got it home it was knackered basically.Looking into things further i noticed there was a 2 inch long crack in the circuit board!I have managed to bridge with solder all the parts that were interrupted by the break of the circuit board.When i was taking the circuit board out of its postion i tried to unscrew a hollow nut that was holding down the main earth to the inside of the amps chassis(o-ring connector at end of earth wire,nut tightened down on it)but when i tried to unscrew this nut it kept turning and wouldn't loosen,so i was left then with an insecure earth connection,i made this more permanent by soldering it in place.So both channels on the amp now work great but im now left with a constant electrical buzzing through the speaker?This has only been since i soldered this earth more securely?or with the handling of the circuit board could it cause this?Anyone any suggestions?thanks!
  Reply With Quote
Old 25th April 2005, 07:16 PM   #2
Netlist is offline Netlist  Belgium
diyAudio Moderator Emeritus
 
Netlist's Avatar
 
Join Date: Jan 2003
Since that earth connection was tightened to the chassis, you could measure with an ohm meter if you have about 0 ohm's between that wire and chassis.
Do you still have hum with all volume controls to 0 and/or inputs unplugged? If not, one of the wires or PCB traces you repaired could be faulty.

/Hugo
  Reply With Quote
Old 25th April 2005, 10:54 PM   #3
diyAudio Member
 
Join Date: Apr 2005
Location: scotland
Yes the noise is there all the time,with all volumes down.
  Reply With Quote
Old 26th April 2005, 05:18 AM   #4
Enzo is offline Enzo  United States
diyAudio Member
 
Join Date: Sep 2004
Location: Lansing, Michigan
WHAT Fender amp do you have? It will make it easier to get out the proper schematic. Make sure the filters are doing their job, one might have cracked its solder. MAke sure you did not alter the grounding arrangements when you repaired hte crack.

If the board was cracked in two so the parts were separate, just repair with jumpers, but if the crack goes from an edge out into the center somewhere and ends there, drill a smal hole at the end of the crack as a strain relief so the crack does not grow.

If you repaired all teh obvious broken traces, go back and look for traces that seemed intact but crossed thre crack. They may have tiny cracks acrosss them.
  Reply With Quote
Old 26th April 2005, 09:13 AM   #5
diyAudio Member
 
Join Date: Apr 2005
Location: scotland
Hi,the amp is a Fender Frontman 15g,i have the schematic but i can't send you it,you probably have it anyway ;-) I just find it strange that this buzzing only started when i made the main earth wire(the one that comes from the main power plug at the rear where you plug in the power cable)more secure by soldering it to the plate it was originally just screwed down by a flaky,hollow,brass coloured nut.I don't know enough about what you mean by 'altering the ground arrangement' when i was bridging the traces that were split.I was as careful as i could be when soldering,solder seems to have gone where i wanted it,what about cleaning the circuit board?There are small traces of flux from the flux and solder i was using,would this flux paste that is left between say two solder points,would this cause the electricity to arc between two points?If you know what i mean.The way i checked the circuit board for splits in the traces was a i shone a strong torch from the rear of the board,then i could see splits easy.I've also taken care of the crack,it did start at the end of the board and worked its way across it,the crack ended in the middle of knowhere away from any traces so i just buried the solder bolt into the end of the crack for a second or two to seal it so to speak,thanks for your help so far!
  Reply With Quote

Reply


Hide this!Advertise here!
Thread Tools Search this Thread
Search this Thread:

Advanced Search

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off


Similar Threads
Thread Thread Starter Forum Replies Last Post
anyone with a low noise preamplifier circuit for guitar? winner Instruments and Amps 3 14th January 2009 06:51 AM
how to make a low noise guitar preamp? winner Instruments and Amps 4 8th January 2009 06:07 PM
Need help fixing my amp - 60hz noise. owdi Solid State 17 17th September 2007 03:44 PM
Frustration with hum and noise in guitar tube amp voivodata Tubes / Valves 18 24th May 2006 10:15 AM


New To Site? Need Help?

All times are GMT. The time now is 02:11 AM.


vBulletin Optimisation provided by vB Optimise (Pro) - vBulletin Mods & Addons Copyright © 2014 DragonByte Technologies Ltd.
Copyright ©1999-2014 diyAudio

Content Relevant URLs by vBSEO 3.3.2