Peavey Renown 400 Issues - Page 5 - diyAudio
Go Back   Home > Forums > Live Sound > Instruments and Amps

Instruments and Amps Everything that makes music, Especially including instrument amps.

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 21st February 2013, 06:08 AM   #41
Enzo is offline Enzo  United States
diyAudio Member
 
Join Date: Sep 2004
Location: Lansing, Michigan
CR6, CR7 are clamps, just as CR13, CR14 at the input stage, and CR25, CR26 at the power amp input. They don't do anything under normal conditions. But in the case of large signals or unwanted voltage on those jacks, they shunt anything beyond the 15v rail voltages, which would have the net effect of LOOKING like reverse voltage to the IC. You don't want voltage on your IC that exceeds its power rails. These clamp diodes are quite common onb PV circuits, especially their mixers.
  Reply With Quote
Old 21st February 2013, 11:58 PM   #42
diyAudio Member
 
Join Date: May 2011
Location: Beverly, Massachusetts, USA
Send a message via AIM to ouimetnick Send a message via Skype™ to ouimetnick
Well I took some readings, so here we go.

U1 Pin 1: 7mV
U1 Pin 7: 19mV
U4 Pin 1: 2.5mV
U4 Pin 7: 1.3mV
U5 Pin 1: -3.3mV
U5 Pin 7: 1.6mV
U6 Pin 1: 6.8mV
U6 Pin 7: 29mV
U7 Pin 1: 9.6mV
U7 Pin 7: 9.8V YES, volts, NOT mV
U8 Pin 1: 1.7mV
U8 Pin 7: 3.9mV
U9 Pin 1: 6.8mV
U9 Pin 7: 6.5mV

DC Offset with preamp disconnected: 10mV
DC Offset with preamp connected: 10mV
DC Offset from the preamplifier: -9.7mV

U1: TL082CP
U4: TL082CP
U5: TL082CP
U6: RC4558P
U7: RC4558P
U8: TL082CP
U9: TL082CP

Last edited by ouimetnick; 22nd February 2013 at 12:11 AM.
  Reply With Quote
Old 22nd February 2013, 12:08 AM   #43
diyAudio Member
 
Join Date: Feb 2008
Location: Jackson,michigan
That would be the reverb driver opamp U7b.

Do you have the reverb unit plugged in?
What are the voltages on pins 5&6 of that chip?
That is high,disconnect the reverb if it is not and see if your noise goes away.

jer
  Reply With Quote
Old 22nd February 2013, 12:10 AM   #44
diyAudio Member
 
Join Date: May 2011
Location: Beverly, Massachusetts, USA
Send a message via AIM to ouimetnick Send a message via Skype™ to ouimetnick
Quote:
Originally Posted by geraldfryjr View Post
That would be the reverb driver opamp U7b.

Do you have the reverb unit plugged in?
What are the voltages on pins 5&6 of that chip?
That is high,disconnect the reverb if it is not and see if your noise goes away.

jer
This is with the reverb disconnected.
  Reply With Quote
Old 22nd February 2013, 12:15 AM   #45
diyAudio Member
 
Join Date: May 2011
Location: Beverly, Massachusetts, USA
Send a message via AIM to ouimetnick Send a message via Skype™ to ouimetnick
Quote:
Originally Posted by geraldfryjr View Post
That would be the reverb driver opamp U7b.

Do you have the reverb unit plugged in?
What are the voltages on pins 5&6 of that chip?
That is high,disconnect the reverb if it is not and see if your noise goes away.

jer
U7 Pin 5: 18.7mV
U7 Pin 6: 19.4mV

Little correction.. I said that the amp was dead silent with the preamp disconnected. Well, not completely true. If you put your ear to the speaker and listen carefully you can hear the hum very faintly, and hear the scratchy sound. The hum and scratching is a bit louder with the preamp connected.

I'm starting to suspect it may be the filter caps in the preamp section.. I know that when filter caps are failing, you get a but of a hum.

The scratchy noise sounds like a dirty pot or like I'm brushing the preamps output to the input on the power amp. A scratchy static noise. As stated, all pots were cleaned and have no effect (well the lead gain post knob lowers the hum when it is set to the 12:00 position, but not by much.) All jacks were replaced, and even when directly soldering the preamp to the power amp, the hum and scratchy noise still remains. All jacks are properly grounded, and all board solder joints were reflowed.

Last edited by ouimetnick; 22nd February 2013 at 12:27 AM.
  Reply With Quote
Old 22nd February 2013, 12:29 AM   #46
diyAudio Member
 
Join Date: Feb 2008
Location: Jackson,michigan
Okay it could be be high becuase it is disconnencted.
I would have to model that circuit in Circuitmaker (spice) to be sure as pins 5 and 6 appear to be normal.
I would tear mine apart to check as well but I don't have the room at the moment.

If you reconnect the reverb unit it may return to normal as it has a lower resistance than the 4.7k resistor that you are measuring across but I still think it should be close to 0V any how.
Did the reverb work?
Don't connect it yet though.

jer
  Reply With Quote
Old 22nd February 2013, 12:30 AM   #47
diyAudio Member
 
Join Date: May 2011
Location: Beverly, Massachusetts, USA
Send a message via AIM to ouimetnick Send a message via Skype™ to ouimetnick
Reverb works great. I just didn't want to unscrew it from the cab.

Should I just pull U7 and see what happens, or is U7 needed to keep everything happy? In some amps (like Hafler) removing the MOSFETs cause the voltage to shift wildly and burn resistors, so they need to stay in to keep it working.

Last edited by ouimetnick; 22nd February 2013 at 12:34 AM.
  Reply With Quote
Old 22nd February 2013, 12:35 AM   #48
diyAudio Member
 
Join Date: Feb 2008
Location: Jackson,michigan
Okay good then U7b is working then.
Is the hum still there when the reverb volume is off?

jer
  Reply With Quote
Old 22nd February 2013, 12:37 AM   #49
diyAudio Member
 
Join Date: May 2011
Location: Beverly, Massachusetts, USA
Send a message via AIM to ouimetnick Send a message via Skype™ to ouimetnick
Hum doesn't change regardless of any control change (except the post gain in the lead channel quiets the hum ever so slightly when set to 12:00 position.)
  Reply With Quote
Old 22nd February 2013, 12:42 AM   #50
diyAudio Member
 
Join Date: Feb 2008
Location: Jackson,michigan
I just read post 45.

You can check and see what your ripple voltages are by measuring the supply rails with your meter set in AC voltage mode.

jer
  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
Peavey Renown Solo Series? Ninesvnsicks Instruments and Amps 9 20th January 2012 09:06 AM
Peavey CS-400 Schematics Wanted Zero Cool Solid State 31 8th August 2009 08:43 PM
Peavey 400 blowing fuse on power up Barnacle Solid State 11 2nd February 2009 10:49 AM


New To Site? Need Help?

All times are GMT. The time now is 10:01 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