Did I do somthing wrong? - diyAudio
Go Back   Home > Forums > Amplifiers > Chip Amps

Chip Amps Amplifiers based on integrated circuits

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 November 2009, 05:59 AM   #1
feyrerm is offline feyrerm  United States
diyAudio Member
 
Join Date: Oct 2009
Default Did I do somthing wrong?

I cant figure out why the output is so low on a pair of p2p wired lm3875's. The wiring seems correct and the lightbulb does not even flicker on the tester. The PS is 300vac 25. I checked the VDC on the rectifier and its a solid 27v on each line. there is sound but it is very low and has trouble driving a 40w 8 ohm load.

Here are some pictures. Any help would be great.

Thanks
Attached Images
File Type: jpg adj01265.JPG (24.2 KB, 188 views)
File Type: jpg adj01268.JPG (27.5 KB, 187 views)
File Type: jpg adj01269.JPG (27.1 KB, 185 views)
File Type: jpg adj01273.JPG (24.0 KB, 184 views)
  Reply With Quote
Old 21st November 2009, 03:11 PM   #2
diyAudio Member
 
lanchile's Avatar
 
Join Date: Sep 2008
Location: AREA 51
Quote:
Originally Posted by feyrerm View Post
I cant figure out why the output is so low on a pair of p2p wired lm3875's. The wiring seems correct and the lightbulb does not even flicker on the tester. The PS is 300vac 25. I checked the VDC on the rectifier and its a solid 27v on each line. there is sound but it is very low and has trouble driving a 40w 8 ohm load.

Here are some pictures. Any help would be great.

Thanks
Well, first what is the value of the potentiometerthere!
and someone correct me if I am wrong here but if you have 25vac on the secondaries you should get over 30 vdc after rectifiers.

Last edited by lanchile; 21st November 2009 at 03:16 PM.
  Reply With Quote
Old 21st November 2009, 03:22 PM   #3
feyrerm is offline feyrerm  United States
diyAudio Member
 
Join Date: Oct 2009
Thanks for the reply. I was mistaken the rectifier puts out a solid 37.2 -/+. The green wire coming from the pot goes to signal ground. Is this not the proper connection?
  Reply With Quote
Old 21st November 2009, 04:10 PM   #4
diyAudio Member
 
lanchile's Avatar
 
Join Date: Sep 2008
Location: AREA 51
Quote:
Originally Posted by feyrerm View Post
Thanks for the reply. I was mistaken the rectifier puts out a solid 37.2 -/+. The green wire coming from the pot goes to signal ground. Is this not the proper connection?
ok.Now what is the value of your potentiometer 10k, 25k, 50k, 100k......
  Reply With Quote
Old 21st November 2009, 05:12 PM   #5
feyrerm is offline feyrerm  United States
diyAudio Member
 
Join Date: Oct 2009
25k I just picked up a 100k to try thinking this might be the problem. Also I am driving it directly from a ps1 1001 model. Could the source be the issue?
  Reply With Quote
Old 21st November 2009, 05:22 PM   #6
diyAudio Member
 
lanchile's Avatar
 
Join Date: Sep 2008
Location: AREA 51
Quote:
Originally Posted by feyrerm View Post
25k I just picked up a 100k to try thinking this might be the problem. Also I am driving it directly from a ps1 1001 model. Could the source be the issue?
25k or 50k are fine but 100k is too high! Get a cd player and try.also make sure all those wires hanging out do not get shorted.
  Reply With Quote
Old 21st November 2009, 06:41 PM   #7
feyrerm is offline feyrerm  United States
diyAudio Member
 
Join Date: Oct 2009
OK so I hooked up a source with a volume control (Ipod). With this source there is more power than I would have ever thought. With this being the case is it my pot or my source? I was oping to mod the PS1 and use it as the permanent audio source in this system, but if the problem is not the pot than I will need to build a preamp to go with it.

Thanks again for the help!
  Reply With Quote
Old 21st November 2009, 09:11 PM   #8
diyAudio Member
 
lanchile's Avatar
 
Join Date: Sep 2008
Location: AREA 51
Quote:
Originally Posted by feyrerm View Post
OK so I hooked up a source with a volume control (Ipod). With this source there is more power than I would have ever thought. With this being the case is it my pot or my source? I was oping to mod the PS1 and use it as the permanent audio source in this system, but if the problem is not the pot than I will need to build a preamp to go with it.

Thanks again for the help!

Ok, if you are using you Ipod as the source with the ipod volume all the way up and you are getting enough power. the problem is not your integrated amp! the problem is with the source you connected before.if I were you I would leave the amp as integrated (with the 25k or 50k pot).leave the volume of your Ipod all the way up and you adjust the volume in your amp only.Good luck buddy!


PS: leave the volume of your Ipod all the way up and then adjust the volume from your amp....up and down and if everything is fine.............your integrated amp is fine!!!

Last edited by lanchile; 21st November 2009 at 09:14 PM.
  Reply With Quote
Old 21st November 2009, 11:17 PM   #9
wwenze is offline wwenze  Singapore
diyAudio Member
 
Join Date: Mar 2008
Can you post the schematics with values?

Last edited by wwenze; 21st November 2009 at 11:20 PM.
  Reply With Quote
Old 22nd November 2009, 12:11 AM   #10
feyrerm is offline feyrerm  United States
diyAudio Member
 
Join Date: Oct 2009
The schmatic is the one right off the nationals website. the parts are from Peter Daniels commercial gainclone site.

# Part Name/Description Digikey Part Number
2 LM3875TF LM3875TF-ND
4 1500uF 50v Panasonic FC Capacitor P10334-ND
4 22.1k ohm resistor (min quantity = 5) PPC22.1KXCT-ND
2 680 ohm resistor (min quantity = 10) P680BBCT-ND
2 220 ohm resistor (min quantity = 5) PPC20.0KXCT-ND
8 On Semiconductor MUR860 fast diodes MUR860OS-ND
2 4.7uF 50v Panasonic FC Capacitor P10315-ND
  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
Portable HIFI ( or somthing close ) ArjenShenzhen Class D 45 5th October 2010 03:11 AM
need some ideas for somthing fun crs1 Everything Else 5 15th December 2007 04:31 PM
LM 2931 better than 78L05 or is there somthing even better? hifi Digital Source 3 27th May 2002 04:53 PM


New To Site? Need Help?

All times are GMT. The time now is 01:26 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