fender amp question - 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 30th April 2006, 04:23 PM   #1
rukr1 is offline rukr1  United States
diyAudio Member
 
Join Date: Apr 2006
Location: atlanta georgia
Default fender amp question

This will probably come off as a really stupid question (so i apologize for wasting anyones time in advance ) but im very new to the world of amps here and a buddy of mine gave me a 1998 Fender Roc Pro 1000 head and there seems to be something wrong with it. the symptoms are like this, the only think wrong is that you you have to turn the volume up all the way in order to hear even the slightest thing. everything powers up no problem. i took it to a local music shop here and had it checked out by someone i thought was somewhat educated in this field, and he told me that its probably not getting enough power and it would probably cost me close to $150 to get it fixed. so i figured i would come to you guys first (since you guys look like you know everything there is to know about amps ). so i did some research and determined it could be a bad power transformer. swapping that out looks like no problem but finding a replacement for it i havent yet been able to. any other suggestions? or anything else i might want to check before replacing the transformer? any advise would be appreciated. thanks in advance!

oh by the way i hope im in the right forum
  Reply With Quote
Old 30th April 2006, 04:46 PM   #2
Netlist is offline Netlist  Belgium
diyAudio Moderator Emeritus
 
Netlist's Avatar
 
Join Date: Jan 2003
No stupid questions here.

Just to make sure: if there is a standby switch, did you flip it?
Are the tubes glowing? Do the big ones get hot? Careful, if they do they can be very hot when touching them.
Oh, and do you have a schematic or link to it?

/Hugo
  Reply With Quote
Old 30th April 2006, 04:52 PM   #3
Netlist is offline Netlist  Belgium
diyAudio Moderator Emeritus
 
Netlist's Avatar
 
Join Date: Jan 2003
Found it, in case we might need it.
http://www.fender.com/support/amp_sc...ematic_B12.pdf

/Hugo
  Reply With Quote
Old 30th April 2006, 05:02 PM   #4
diyAudio Member
 
Join Date: Jul 2005
Location: North Derbyshire
Fender are nice, because they provide all their diagrams, have a look here for this one.

This shows it's a transistor amplifier, with a single valve used as two diodes on one of the input channels.

First thing to do is find which part of the circuit the fault is in, preamp or power amp.
__________________
Nigel Goodwin
  Reply With Quote
Old 30th April 2006, 05:14 PM   #5
Netlist is offline Netlist  Belgium
diyAudio Moderator Emeritus
 
Netlist's Avatar
 
Join Date: Jan 2003
Looks like I was a bit too fast about the tubes. There is indeed only one.
Consequently, there will be no standby switch.
So before I posts other nonsense, Iíll have a look at the schematic.
Can you tackle basic electronics? Like checking fuses, voltages?

/Hugo
  Reply With Quote
Old 1st May 2006, 03:36 AM   #6
rukr1 is offline rukr1  United States
diyAudio Member
 
Join Date: Apr 2006
Location: atlanta georgia
basic electronics i can tackle... i hope do you think it could be the power transformer?? if you could guide me through what i need to check that would be awesome and a huge help. thanks hugo!
  Reply With Quote
Old 1st May 2006, 09:18 AM   #7
Netlist is offline Netlist  Belgium
diyAudio Moderator Emeritus
 
Netlist's Avatar
 
Join Date: Jan 2003
Ok, assuming you connected everything as it should be; input signal present, you fiddled with all buttons and switches and you still have no sound, take out the fuse XF1 and measure if itís broken.
A word of warning: Donít trust the mains switch and pull out the mains before taking out the fuse.
The second check needs mains voltage so be careful.
Check the voltage on TP23, TP24, TP26 and TP27 with respect to ground, which is CP4.

Let us know what you found.

/Hugo
  Reply With Quote
Old 1st May 2006, 11:30 AM   #8
diyAudio Member
 
Join Date: Jul 2005
Location: North Derbyshire
Quote:
Originally posted by rukr1
basic electronics i can tackle... i hope do you think it could be the power transformer??
It's very unlikely to be the transformer.
__________________
Nigel Goodwin
  Reply With Quote
Old 1st May 2006, 04:33 PM   #9
rukr1 is offline rukr1  United States
diyAudio Member
 
Join Date: Apr 2006
Location: atlanta georgia
well heres what i got

TP23 39.2
TP24 17.8
TP26 -39.6
TP27 -17.1

fuse seems to be fine
  Reply With Quote
Old 1st May 2006, 04:36 PM   #10
diyAudio Member
 
Join Date: Jul 2005
Location: North Derbyshire
Try pushing a jack plug in and out of the effect return socket a few times, it could be dirty switch contacts on that?. The power supply voltages you took look fine!.
__________________
Nigel Goodwin
  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
Fender help Docc25 Instruments and Amps 3 2nd January 2013 11:18 PM
Fender 6L6 Amp... HELP!!! mjarve Tubes / Valves 18 28th November 2010 07:06 PM
Fender 6G15 Reverb Question bluezrider Parts 1 21st February 2009 08:00 AM
Fender Pro Amp atmars Tubes / Valves 1 23rd November 2008 02:30 AM
Fender Footswitch question R_Atkinson Parts 0 10th May 2007 01:17 AM


New To Site? Need Help?

All times are GMT. The time now is 11:34 PM.


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