Rockford Fosgate T30001bd - Page 5 - diyAudio
Go Back   Home > Forums > General Interest > Car Audio

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 19th March 2013, 11:26 PM   #41
diyAudio Member
 
Join Date: Feb 2008
Send a message via AIM to MatthewS Send a message via MSN to MatthewS Send a message via Yahoo to MatthewS
Just now? Yesterday? In 2009? I'm trying to follow but you never mentioned anything about it after post #16 IIRC. Can you bring us up to speed on what/where you've found that has not been posted?
  Reply With Quote
Old 19th March 2013, 11:34 PM   #42
ultra is offline ultra  Greece
diyAudio Member
 
ultra's Avatar
 
Join Date: Jun 2005
Location: Athens
you are right, sorry i completely forgot about it.
I have found the break since #20.
It was very close to a pad, really difficult to see it.
  Reply With Quote
Old 19th March 2013, 11:40 PM   #43
diyAudio Member
 
Join Date: Feb 2008
Send a message via AIM to MatthewS Send a message via MSN to MatthewS Send a message via Yahoo to MatthewS
Ok, can you identify the frequency the hum is on? Hz/Khz.
  Reply With Quote
Old 19th March 2013, 11:42 PM   #44
diyAudio Member
 
Join Date: Nov 2003
Location: Louisiana
You need to repair the -6v regulator.
  Reply With Quote
Old 19th March 2013, 11:56 PM   #45
diyAudio Member
 
Join Date: Feb 2008
Send a message via AIM to MatthewS Send a message via MSN to MatthewS Send a message via Yahoo to MatthewS
Posts 9, 16 & 20 suggest he has -6.. albeit a bit low @ -5.88. In post 36 is was too high over -8 volts. This is tough for me to follow because things are being done between posts and we're just not in the loop. Nice catch Perry.
  Reply With Quote
Old 20th March 2013, 03:46 AM   #46
ultra is offline ultra  Greece
diyAudio Member
 
ultra's Avatar
 
Join Date: Jun 2005
Location: Athens
the internet connection where i work is down so i have to go up two flights of stairs to post and i cannot remember everything.
After some examination of the auxiliary voltages, (Perry was right) i managed to get things a bit straight.
I noticed that whenever i touched R312 the noise went away for a second and after re-soldering R312 much of the noise was gone.
I can -sometimes- completely eliminate the noise for just a sec if i turn up and down the gain pot. But it always comes back again.
Now, the high frequency noise is still present, but at least the amp produces audio at the output with signal fed to the RCAs. However, it sounds distorted.
Here is what i mean (amp if fed with 100Hz sine)
Pic 1 the signal between C355 and R300
pic 2 pin 1 of U300
pic 3 the output of the amp at low volume
pic 4 the output of the amp at a bit higher volume....
thats why it sounds distorted
Attached Images
File Type: jpg C355 and R300.JPG (880.3 KB, 33 views)
File Type: jpg pin 1 U300.JPG (841.0 KB, 29 views)
File Type: jpg output low volume.JPG (857.0 KB, 26 views)
File Type: jpg output higher volume.JPG (875.5 KB, 28 views)
  Reply With Quote
Old 20th March 2013, 03:58 AM   #47
diyAudio Member
 
Join Date: Nov 2003
Location: Louisiana
For op-amps 300, 301 and 302, do you read anything more than about 0.01v DC if you place the meter probes on pins 3/4 or 5/6?

Is there any DC offset when you do not inject signal?
  Reply With Quote
Old 20th March 2013, 04:52 AM   #48
ultra is offline ultra  Greece
diyAudio Member
 
ultra's Avatar
 
Join Date: Jun 2005
Location: Athens
All the above op-amps have -6V at pins 4 and 6V at pins 8.
Assuming that you mean pins 2/3 and 5/6, here is what i have referenced to gnd with no signal into the amp

U300
pin 1 0.039
pin 2 0.007
pin 3 0.005
pin 5 0.003
pin 6 0.008
pin 7 0.007

U301
pin 1 0.027
pin 2 0.075
pin 3 0.073
pin 5 0.073
pin 6 0.031
pin 7 0.18

U302
pin 1 -0.021
pin 2 0.007
pin 3 0.007
pin 5 -0.007
pin 6 -0.022
pin 7 0.31

if i inject signal to the RCAs, at C355/R300 i get 0.045VDC and around -0.45VDC at the output (it grows in relation to the output swing).
  Reply With Quote
Old 20th March 2013, 05:18 AM   #49
diyAudio Member
 
Join Date: Nov 2003
Location: Louisiana
Yes. 2/3.

In the output photos above, it appears that you have about 30v of offset.

Am I reading the scope wrong?
  Reply With Quote
Old 20th March 2013, 05:29 AM   #50
ultra is offline ultra  Greece
diyAudio Member
 
ultra's Avatar
 
Join Date: Jun 2005
Location: Athens
How can you read it wrong?
the higher the output the greater the offset.
i may have not expressed it properly on #48
  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
rockford fosgate t30001bd dips1982 Car Audio 17 27th December 2013 11:01 PM
Rockford T30001bd shawnk Car Audio 22 25th March 2012 02:39 PM
Rockford t30001bd-big problem please help rezzyr Car Audio 3 21st September 2011 08:28 PM
Rockford Fosgate dtisme Car Audio 1 6th October 2010 12:39 AM
Rockford Fosgate T30001BD mike49504 Car Audio 71 26th March 2010 10:22 AM


New To Site? Need Help?

All times are GMT. The time now is 09:55 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