The Objective2 (O2) Headphone Amp DIY Project - Page 231 - diyAudio
Go Back   Home > Forums > Amplifiers > Headphone Systems

Headphone Systems Everything to do with Headphones

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 March 2012, 10:38 AM   #2301
diyAudio Member
 
sofaspud's Avatar
 
Join Date: Nov 2005
Location: San Antonio
If you don't have the op amps installed, it's pretty hard to kill the circuit. And a typical anti-static mat shouldn't short that much current. I wouldn't completely rule it out.
You've checked for bridges, so now check that the capacitors C2 to C5, diodes D3 & D4, and regulators are installed and oriented correctly. If they are, measure the AC output of the transformer, the DC input to the regulators, and the DC output of the regulators. If the caps bulge kill the power immediately.
__________________
It is error only, and not truth, that shrinks from enquiry. - Thomas Paine
  Reply With Quote
Old 31st March 2012, 05:21 PM   #2302
BlueRob is offline BlueRob  Mexico
diyAudio Member
 
Join Date: Dec 2008
Quote:
Originally Posted by lorriman View Post
...I should add that at one point, after the initial failed test, I accidentally put the power in with the device switched *on*. It was only for a couple of seconds but evidently if the power circuit is screwed then I may have killed the amp circuit as well. The LED did come on.
I´m by far be the most qualified O2 builder around here but I will give you some things to consider.

Did you test the AC wall transformer output? I assume yes since you problem began on the next step.

Do NOT use an electrostatic bag as "base" yes, as you already figured out is could cause a short. I work on a wooden surface or mouse pad (neoprene I guess)

Did you matched the corresponding polarities of the electrolytic Caps with the ones of the board? Remember the have a + and - side.

Same as above for the diodes around.

Last but not least...solder bridges.

My suggestion would be to do the above visual checks and replace the "almost popped" caps and start over with test form step one.

HTH
  Reply With Quote
Old 1st April 2012, 11:36 AM   #2303
diyAudio Member
 
Join Date: Nov 2011
Location: Surrey
Thanks for the help, guys. It seems it was the capacitors after all. I could have sworn I had correctly followed RS's instructions. Unfortunately I interpreted this :

"Note the electrolytic capacitors “face” different directions. The large strip is negative and should match up with the mark on the circle on the board. The large caps have the negative stripe on the right and the small caps (C8, C9) on the left."

...as meaning the length of the longer wire coming out of the bottom of the capacitors; since they consistently have one wire longer. I should have read that sentence more carefully; though it was 4 o'clock in the morning. I've assumed all the electrolytics are dead and replaced them and marvellously my newbie (ie. no prior experience of soldering and near zero knowledge of electronics) O2 passes all the tests and works and is now driving my current-hungry T50rp Orthodynamics to satisfactory volume levels. I'm jolly glad I didn't decide on the confidence I had in my build and simply plug in the opamps and go for it without testing first; I was tempted.

Reading people's comments I had expected to need to drive my T50rp's on the lower gain setting. However it seems that that may be true of ipods but the Sansa clip has so little voltage in the first place that I can actually wear the headphones with the o2 set to maximum gain and max volume on both O2 and clip; though it is too loud. Certainly, I have to use the 6.5x gain setting to get satisfactory volume. That was a surprise. I should add that I have no (known) hearing problems.

Right now I'm at a friends place but I can't wait to get home to stroke my new baby.

Thanks again to all those who help us (probably quite irritating) clueless newbies.

As for replacing the dead capacitors (in order to complete two more builds), does anyone have any suggestions? For example, must I return to Mouser to get the right quality or specs, or is there somewhere cheaper that will do just fine (I'm in the UK)? I've noted RS's warning about substandard rejects being sold on on ebay, and my experience is that Amazon is often a dumping ground also. In the meantime Mouser and Farnell's postage is a bit on the high side for just 4 small capacitors.
  Reply With Quote
Old 1st April 2012, 11:56 AM   #2304
diyAudio Member
 
sofaspud's Avatar
 
Join Date: Nov 2005
Location: San Antonio
Glad to hear of your success. Testing is virtually mandatory. We all make mistakes; newbies just make more than others. I have no suggestions for where to get the components you need since I'm too far away. Because of the layout, you'll want to find caps that have the same lead spacing and the same or smaller dimensions. A higher value and voltage rating is OK.
__________________
It is error only, and not truth, that shrinks from enquiry. - Thomas Paine
  Reply With Quote
Old 1st April 2012, 12:15 PM   #2305
diyAudio Member
 
Join Date: Oct 2011
Assuming that it's C2 - C5 that you want to replace, if you don't want to risk Ebay then Maplins part VH47B (470uF, 35V electrolytic) @46p per item should be perfectly satisfactory and easy to obtain.
  Reply With Quote
Old 3rd April 2012, 09:15 AM   #2306
diyAudio Member
 
Join Date: Nov 2011
Location: Surrey
Quote:
Originally Posted by greenalien View Post
Assuming that it's C2 - C5 that you want to replace, if you don't want to risk Ebay then Maplins part VH47B (470uF, 35V electrolytic) @46p per item should be perfectly satisfactory and easy to obtain.
Great, thanks for that, greenalien.
  Reply With Quote
Old 3rd April 2012, 09:16 AM   #2307
diyAudio Member
 
Join Date: Nov 2011
Location: Surrey
Quote:
Originally Posted by sofaspud View Post
..... A higher value and voltage rating is OK.
Thanks for that. That's good to know.
  Reply With Quote
Old 4th April 2012, 07:20 AM   #2308
diyAudio Member
 
Join Date: Oct 2011
Default CE Marking

There's a regulation that all electronic apparatus sold in the European Union has to pass compliance testing to ensure that it meets all EU standards and be CE marked. I became aware of this when the much-publicised Raspberry Pi microcomputer suffered yet another distribution delay after the suppliers discovered that it would have to be CE certified, despite being an uncased device aimed at the hobbyist and education markets.
I have a suspicion that this legislation may apply to anyone selling batches of completed O2 units, and also to the upcoming ODAC, as it's a complete board, not a kit.
  Reply With Quote
Old 4th April 2012, 12:56 PM   #2309
swalter is offline swalter  Switzerland
life is beautiful...
diyAudio Member
 
Join Date: Jan 2012
Location: Switzerland
Quote:
Originally Posted by greenalien View Post
There's a regulation that all electronic apparatus sold in the European Union has to pass compliance testing to ensure that it meets all EU standards and be CE marked. I became aware of this when the much-publicised Raspberry Pi microcomputer suffered yet another distribution delay after the suppliers discovered that it would have to be CE certified, despite being an uncased device aimed at the hobbyist and education markets.
I have a suspicion that this legislation may apply to anyone selling batches of completed O2 units, and also to the upcoming ODAC, as it's a complete board, not a kit.
Hi greenalien,

interesting thought, and worth to look up. I had a look at the EU directives and the only one that would apply to O2 and ODAC is DIRECTIVE 2006/95/EC - relating to electrical equipment designed for use within certain voltage limits. This directive states in article one:

"Article 1
For the purposes of this Directive, ‘electrical equipment’ means
any equipment designed for use with a voltage rating of between
50 and 1 000 V for alternating current and between 75 and
1 500 V for direct current, other than the equipment and
phenomena listed in Annex II."

where Annex II reads:

"ANNEX II
Equipment and Phenomena outside the Scope of this Directive
Electrical equipment for use in an explosive atmosphere
Electrical equipment for radiology and medical purposes
Electrical parts for goods and passenger lifts
Electricity meters
Plugs and socket outlets for domestic use
Electric fence controllers
Radio-electrical interference"

none of above applies for O2 or ODAC, so I assume they would not need the CE Conformity Marking nor the EC Declaration of Conformity. The only part this would apply to is the power supply for the O2, and the once I sell are certified

I will double check the same with the producer of the ODAC though...

Stefan
__________________
everything O2 and ODAC related can be found here: www.headnhifi.com - your DIY and audio resource
or have a peek in our vendor forum: http://www.diyaudio.com/forums/head-n-hifi-walter/
  Reply With Quote
Old 4th April 2012, 03:53 PM   #2310
dtproff is offline dtproff  United States
diyAudio Member
 
Join Date: Oct 2008
Location: Plano, TX, USA
I may be wrong (and I have been before) but I believe that since the power supply plugs into your completed unit, the entire assembly must be CE qualified. For example, if you look on you laptop you will see that there is a whole string of certifications including CE that are on the label.

Look at it another way... HP/Dell would sell there laptops without power adapters if they thought they could get away with not having to have compliance standards. It's cheaper.

This is not just about safety but also EMC compliance. There are hobbyist exemptions but I believe that a fully assembled unit does not fall into that category. So I believe that it must also be EMC compliant.

Anyway... That is just my $US0.02 worth the advice.

Tony
  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
Headphone amp project grahamfocal Headphone Systems 7 21st June 2011 05:28 PM
My latest project - DAC + headphone amp gmarsh Digital Line Level 105 13th December 2010 02:31 PM
My headphone amp project trifidmaster Headphone Systems 2 22nd December 2008 03:52 PM
Mini Ipod headphone amp DIY project Nordic Headphone Systems 14 11th March 2007 02:35 PM
Need help for a battery headphone amp project dismalonyx Headphone Systems 1 15th April 2004 11:22 PM


New To Site? Need Help?

All times are GMT. The time now is 12:11 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