Strange voltage curves - diyAudio
Go Back   Home > Forums > Amplifiers > Pass Labs

Pass Labs This forum is dedicated to Pass Labs discussion.

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 14th June 2002, 06:42 PM   #1
diyAudio Member
 
Join Date: Apr 2002
Location: Netherlands
Unhappy Strange voltage curves

Hello,

I have a working Aleph 4, however when I look with a scoop on the traces of the + and - voltages of left and right channel I get very strange views... Only the first trace looks like I would expect. both channels are wired the same. They are all very different. Timebase and amplify are all the same for all pictures!

I have 0.22uf 250V around the rectifier bridge and across the + 0 - side of the elco's. You can see this on a picture below.

channel 1 +
Click the image to open in full size.

channel 1 -
Click the image to open in full size.

channel 2 +
Click the image to open in full size.

channel 2 -
Click the image to open in full size.

Help what can it be!

Edwin
  Reply With Quote
Old 14th June 2002, 06:46 PM   #2
diyAudio Member
 
Join Date: Apr 2002
Location: Netherlands
And a small picture of my Aleph 4!

Click the image to open in full size.
  Reply With Quote
Old 14th June 2002, 06:57 PM   #3
tiroth is offline tiroth  United States
diyAudio Member
 
Join Date: Dec 2001
Location: Pittsburgh, PA, USA
none of your pix work
  Reply With Quote
Old 14th June 2002, 07:00 PM   #4
diyAudio Member
 
Join Date: Apr 2002
Location: Netherlands
Quote:
Originally posted by tiroth
none of your pix work
strange, I just rechecked on a other PC and the work... perhaps the internet is slow to by providers server. It is located in the Netherlands.

Edwin
  Reply With Quote
Old 14th June 2002, 07:09 PM   #5
diyAudio Member
 
Join Date: Nov 2001
Location: Haarlem
Send a message via MSN to blank527
Pics works fine by me!
Great work!
Strange voltage readings, have'nt got a clue.
Are these readings taken whilst with a source, or with no source.
Maybe it changes when you put your source off.
Remco
  Reply With Quote
Old 14th June 2002, 07:13 PM   #6
fcel is offline fcel  United States
diyAudio Member
 
Join Date: Sep 2001
Location: LA County
Default Capacitor

Are those Phillip 26000uF/75V capacitors with the 3 connectors? I hope they are not the cause of the "problem" because I just bought a bunch of them.
By the way, if they are 26,000uF each, why do you need some many per channel? You just want to do way overkill since it's DIY?
  Reply With Quote
Old 14th June 2002, 07:32 PM   #7
diyAudio Member
 
Join Date: Apr 2002
Location: Netherlands
Default Re: Capacitor

Quote:
Originally posted by fcel
Are those Phillip 26000uF/75V capacitors with the 3 connectors? I hope they are not the cause of the "problem" because I just bought a bunch of them.
By the way, if they are 26,000uF each, why do you need some many per channel? You just want to do way overkill since it's DIY?
For the record; these are pictures of the power supply + and - rails... not of the output or input of the amplifier.

The channel 1 has the least hum.

They are 63V 22000uf BC components (philps) with 2 times M5 screw on connectors.

Yes, DIY overkill! To lower the ripple of the powersupply, however something does not work!

Edwin
  Reply With Quote
Old 14th June 2002, 07:48 PM   #8
fcel is offline fcel  United States
diyAudio Member
 
Join Date: Sep 2001
Location: LA County
1. Does the transformer has shielding?
2. Did you try installing the transformers side by side instead of on top of each other?
  Reply With Quote
Old 14th June 2002, 07:51 PM   #9
diyAudio Member
 
Join Date: Apr 2002
Location: Netherlands
Quote:
Originally posted by fcel
1. Does the transformer has shielding?
2. Did you try installing the transformers side by side instead of on top of each other?
The transformers do not have shielding. They are 1000VA 40-0-40 transformers.

I mounted them on top of each because of easy fixing. I did not try to move them around, as they are bolted on to the wood, and soldered with thick wires (do not bend easy). Can this be a part of the problem? I looked once in a Plinius amp and they do the same trick.

Edwin
  Reply With Quote
Old 14th June 2002, 08:17 PM   #10
HDTVman is offline HDTVman  United States
diyAudio Member
 
Join Date: Aug 2001
Location: Chicago area
Edwin a couple of quick questions.

1. What do you have as a load for the amp while testing?

2. Do you have the bias set for both channels?

3. Is there any DC ofset at the output?

Just looking at the scope traces it looks like channel 2 has a higher bias current setting than channel 1. It also looks like there may be a - offset in both channels (more current from the - supply that the + supply).

The only other thing I can think of that would cause a wave form like this is that some of the power supply caps may have a bad connection of are defective.

Hope this helps.
BZ
__________________
What ever makes the tunes flow
  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
Ripple filtering help... strange slow rise and fall of voltage jlw Tubes / Valves 7 30th August 2008 06:50 AM
Derive Triode Curves from Pentode Curves? dsavitsk Tubes / Valves 3 14th May 2007 07:10 PM
Strange voltage on floating chassis. Arx Chip Amps 18 22nd February 2006 08:50 AM
Brazil, and some strange laws, not too much strange! destroyer X Everything Else 0 11th September 2004 01:38 PM


New To Site? Need Help?

All times are GMT. The time now is 12:35 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