transformer question - 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 31st July 2012, 10:33 PM   #1
diyAudio Member
 
Join Date: Feb 2012
Default transformer question

A friend bought a half built chip amp off ebay that I have been assembling ito a chassis for him. It came with a transformer. the color scheme on it is red, yellow, white, blue and blue. what is what, or how can I test for it?
  Reply With Quote
Old 1st August 2012, 12:12 AM   #2
Minion is offline Minion  Canada
diyAudio Member
 
Join Date: May 2006
Location: Cowican Bay , vancouver island
Are those the secondary wires or all the wires ?? Generally there will be 2 or 3 wires that come out of the transformer at a different spot as the rest of the wires , the thicker wires will generally be the primary wires and the thinner wires are the secondary wires ......

can you post the primary wire colors and the secondary wire colors , and maybe a picture ??
  Reply With Quote
Old 1st August 2012, 12:25 AM   #3
diyAudio Member
 
Join Date: Feb 2012
Thanks, I actually figured it out. Measured the ohms on the secondary and used the two that gave me a reading and the amp works. I know that was a bad explanation!
  Reply With Quote
Old 1st August 2012, 12:47 AM   #4
diyAudio Member
 
Join Date: Feb 2012
I think I have it figured out, measured the two blue secondary wires with an ohm meter and used them. The amp work, plays for about 4 or 5 minutes then starts to clip and then stops playing.
  Reply With Quote
Old 1st August 2012, 12:49 AM   #5
kevinkr is offline kevinkr  United States
diyAudio Moderator
 
kevinkr's Avatar
 
Join Date: Sep 2004
Location: Boston, Massachusetts
Blog Entries: 6
How hot is the chip when it quits playing? I'm thinking the internal SOA protection/thermal limiter is kicking in due to inadequate heatsinking.

What is the supply voltage? Is a center tap required or does this amp have an output coupling capacitor?
__________________
"Extraordinary claims require extraordinary evidence." - Carl Sagan
  Reply With Quote
Old 1st August 2012, 01:04 AM   #6
diyAudio Member
 
Join Date: Feb 2012
They aren't very hot at all. Its built in an old alexis pro amp chassis so the heatsinks should be plenty big. The supply voltage is 32V DC. Center tap could potentially be the problem. A rough layout of this powerboard is as follows- input ground and input-to four small 1uf wima type caps-4 50v 10,000uf caps-two .22uf film caps-to the positive rail ground and negative rail. I have both amp boards connected to this point.
  Reply With Quote
Old 1st August 2012, 01:15 AM   #7
diyAudio Member
 
Join Date: Feb 2012
The supply voltage is not changing at all when the clipping occurs/when the channels cut out
  Reply With Quote
Old 1st August 2012, 03:08 AM   #8
diyAudio Member
 
Join Date: Feb 2012
The chip is an LM 3886
  Reply With Quote
Old 1st August 2012, 03:43 AM   #9
kevinkr is offline kevinkr  United States
diyAudio Moderator
 
kevinkr's Avatar
 
Join Date: Sep 2004
Location: Boston, Massachusetts
Blog Entries: 6
I'm assuming this amplifier uses a bipolar supply - most LM3886 do and you either need two secondaries or one with a center tap on the winding.

Can you post some pix and carefully make a few measurements of the windings when the transformer is powered.
__________________
"Extraordinary claims require extraordinary evidence." - Carl Sagan
  Reply With Quote
Old 1st August 2012, 05:31 AM   #10
diyAudio Member
 
Join Date: Feb 2012
If any parts of the wiring is not clear from the pictures let me know

Click the image to open in full size.
Click the image to open in full size.
Click the image to open in full size.
Click the image to open in full size.
  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
Newbie Question - Power Transformer vs Isolation Transformer SparkyPete Tubes / Valves 10 2nd November 2012 06:13 PM
Question on transformer Buzzy Solid State 10 24th March 2008 12:21 PM
Another transformer question kneadle Chip Amps 12 13th May 2006 08:08 PM
A Transformer question alexmoose Tubes / Valves 8 18th April 2006 01:00 PM
transformer question KCC Solid State 5 2nd July 2002 04:33 AM


New To Site? Need Help?

All times are GMT. The time now is 09:42 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