HP339A distortion analyser - Page 4 - diyAudio
Go Back   Home > Forums > Design & Build > Equipment & Tools

Equipment & Tools From test equipment to hand tools

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 22nd October 2013, 10:43 PM   #31
diyAudio Member
 
Join Date: May 2011
Location: Clifton, Maine
I would really like that also Dick. It think it would beneficial to many.

I have enjoyed your "greening" projects on your web site. Your projects are well documented and easy to understand. Maybe you could add this HP339 project to your web site.

I built your Twin T Notch Filter and now it is an important part of my bench equipment.
  Reply With Quote
Old 23rd October 2013, 12:48 AM   #32
davada is offline davada  Canada
diyAudio Member
 
Join Date: Jul 2004
Location: Fort St John, BC Canada
Quote:
Originally Posted by tschrama View Post
Highly appriciated Richiem ! meanwhile I still have to figure out what was damaged in my 339A...
You have input damage. There is a string of diodes clamps to the power rails and a dual gate fet. If the fuse is open it's likely these diodes are shorted. That's what they are there for.
There is also the possibility a resistor is opened as well. Damage to the amplifier is possible but doubtful.

If you can input a signal then you can trace it with a scope and see where it stops or attenuates more than it should. Also look for open ground track.
__________________
David.
  Reply With Quote
Old 23rd October 2013, 06:46 AM   #33
diyAudio Member
 
Join Date: Jul 2001
Location: The Netherlands
Thank you so much for all those tips!

Update from last night:

Good news: Found the tiny little fuse on the oscilator output. It is not on the PCB, but point-to-point soldered from a tagboard to the output level switch. It was blown and saved the rest of the oscilator. I bridged the tiny blown fuse and ... Voila a nice sine appeared

Bad news: the Fundamental Rejection Circuit still wont attenuated more than 10dB. On the scope the monitor still shows a large fundamental which is a bit noisy..?

This is bad news, because the rejection circuit is pretty complicated, at least to me, and I doubt I can fix it.
  Reply With Quote
Old 23rd October 2013, 06:48 AM   #34
diyAudio Member
 
Join Date: Jul 2001
Location: The Netherlands
PS

0.006% I noted down on the front panel my HP 334A (but yesterday I managed 0.004% at 10Kz, apparently a sweet spot on the dials) , on the HP339 I noted 0.0007%, on my KH 4400 I noted 0.0006%.
  Reply With Quote
Old 23rd October 2013, 05:25 PM   #35
RNMarsh is offline RNMarsh  United States
diyAudio Member
 
RNMarsh's Avatar
 
Join Date: May 2012
Location: 2457 Cascade Trail; Cool, CA. 95614
There are other fuses inside... maybe one of those went also?

-RM
  Reply With Quote
Old 23rd October 2013, 05:27 PM   #36
RNMarsh is offline RNMarsh  United States
diyAudio Member
 
RNMarsh's Avatar
 
Join Date: May 2012
Location: 2457 Cascade Trail; Cool, CA. 95614
Quote:
Originally Posted by tschrama View Post
PS

0.006% I noted down on the front panel my HP 334A (but yesterday I managed 0.004% at 10Kz, apparently a sweet spot on the dials) , on the HP339 I noted 0.0007%, on my KH 4400 I noted 0.0006%.

Those are very good numbers for those make/models and should be very useful for many projects.

have you made any mods to them - which/what?

-RNM
  Reply With Quote
Old 23rd October 2013, 06:21 PM   #37
diyAudio Member
 
Join Date: Jul 2001
Location: The Netherlands
My 334A definitly has a sweet spot were you can get very respectable figures. Tuning the manual-frequency-dial a bit to the low side gives you best THD resolution: down to 0.004% at 10KHz, dominated heavely by 2nd harmonic. No Mods, just finding the sweet spot.

The HP 339A and KH4400 I bought because I got emthousiastic due to the 334A, but never used it that much... I managed to break it soon after I got it.
  Reply With Quote
Old 29th October 2013, 09:28 PM   #38
RNMarsh is offline RNMarsh  United States
diyAudio Member
 
RNMarsh's Avatar
 
Join Date: May 2012
Location: 2457 Cascade Trail; Cool, CA. 95614
See new thread "Who wants to build a distortion analyzer" Line #19. All done with relay for switching and meter reads down to -120dB :-)

-RNM
  Reply With Quote
Old 30th October 2013, 03:47 AM   #39
richiem is offline richiem  United States
diyAudio Member
 
richiem's Avatar
 
Join Date: Sep 2010
Location: Grapeview, WA
@tschrama -- lack of auto tuning in the notch filter, most likely caused by a bad amp or other component. This circuit looks complicated just due to the large number of components, but it is fairly simple. Two opto-resistors (LED and photocell in a sealed package) do the actual tuning adjustments -- they are known to be problematic. Just use a diode tester to check the LED section.

If that's good, then try measuring the resistance of the photocell -- it should be very high if the LED is off. If it's low that's a problem. Conversely, if the LED is OK, then put 1kohm in series with it and run it slowly up on a variable DC supply (make sure polarity is correct) and measure the photocell R -- it should go down as the LED intensity increases. But note other comments above, about the need to check the input circuits to be sure signal is actually getting to the notch filter and the tuning circuitry.

Good luck.
__________________
...................
Dick Moore
  Reply With Quote
Old 31st October 2013, 06:47 PM   #40
diyAudio Member
 
Join Date: Jul 2001
Location: The Netherlands
Quote:
Originally Posted by richiem View Post
@tschrama -- lack of auto tuning in the notch filter, most likely caused by a bad amp or other component. This circuit looks complicated just due to the large number of components, but it is fairly simple. Two opto-resistors (LED and photocell in a sealed package) do the actual tuning adjustments -- they are known to be problematic. Just use a diode tester to check the LED section.

If that's good, then try measuring the resistance of the photocell -- it should be very high if the LED is off. If it's low that's a problem. Conversely, if the LED is OK, then put 1kohm in series with it and run it slowly up on a variable DC supply (make sure polarity is correct) and measure the photocell R -- it should go down as the LED intensity increases. But note other comments above, about the need to check the input circuits to be sure signal is actually getting to the notch filter and the tuning circuitry.

Good luck.
Once more: thanks for the tips! Will try to check out these 2 photocells.

Still working on the unit in very scarce evening hours. Taking out the whole vertical mounted PCB (I think balance and phase error detectors) actually make harly any differende to the Nulling.. -10dB in 3Volt input.. surprissingly lower input gives better Nulling , up to 30dB...?
  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
FS: Sweet!! HP339A Distortion Measurement Set cowboy99 Swap Meet 7 24th October 2009 10:37 AM
Distortion analyser circuit steevo Solid State 12 21st July 2008 01:42 AM
IM Distortion Analyser Alain Dupont Parts 2 6th January 2005 02:48 AM
HP334A Distortion Analyser Netlist Swap Meet 1 14th October 2003 10:33 PM
HP333A Distortion Analyser Netlist Equipment & Tools 12 13th October 2003 09:40 PM


New To Site? Need Help?

All times are GMT. The time now is 08:02 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