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 19th April 2012, 01:03 PM   #1
diyAudio Member
 
Join Date: Jan 2011
Location: in a small town called Senlis, north of Paris
Default Trouble on Zen V9

Hi everyone

I am trying to start a Zen V9 and it just won't work.
Here are how things are. I use the NP article 'Zen variation #9'
Q4: Supply is 30 V to start with. Professional power supply, no problem there with a current limit set to 3 amps. VD is 30, VS is about 28V.
Q3: VD is 28v, VS is 26.2V. Replaced ZTX by a BC107, adjusted pinout of ourse, the BC is in fine shape. Shows the regular 0.6V between B and E, C to
Vout is 26.2V and here is the problem: the 25K pot does not have any action, the VG of Q2 remains stuck at a max of 0.7V, whichever position it is set.
For the testing I replaced Q1 by an AMmeter.
No current goes by.
Q2 is blocked, VD as said and VS to GND, VG to 0.7V.

I tested all mosfets and they run fine, it seems that they are OK. I even replaced Q2 by an IRFP044 to compare, o difference.

What is your advice ?

Thanks to all in advance.
  Reply With Quote
Old 19th April 2012, 04:43 PM   #2
diyAudio Member
 
vdi_nenna's Avatar
 
Join Date: Oct 2000
Location: PA, USA
Blog Entries: 1
Send a message via Yahoo to vdi_nenna
Hi Billy,

I had an issue with my Zen 9 two weeks ago. I believe, in the end, the problem was a cold solder. A loose resistor near Q5.
Zen 9 - Troubleshoot Bad Channel

If nothing burned, then you are more than half-way there!
Are both channels not functioning? Are they behaving the same?

With your power supply, the Drain voltage at Q2 should be set to close to 14v, set by P1. So, if you are not seeing 14v on the Drain of Q2, check the soldering on Q2 and all components connecting near Q2. Perhaps you should try to replace Q2.

Also, check the voltage across R4 through R6. Article says it should be around .66v to create a 2 amps constant current. What voltage are you seeing across R4-6?
__________________
I build, therefore I am.

Last edited by vdi_nenna; 19th April 2012 at 04:49 PM.
  Reply With Quote
Old 20th April 2012, 12:05 PM   #3
diyAudio Member
 
Join Date: Jan 2011
Location: in a small town called Senlis, north of Paris
Only one channel built.
A this pont I am redoing a new PCboard to have all Transistors from the same side.
It will allow me to resolder everything, just in case.
I don't think it is the cause of my roblem since I double checked already the soldering.
I'll let you know how it turns out.
No voltage between both sides of R4-6, coherent withno current flow. The Q2 is blocked.
  Reply With Quote
Old 22nd April 2012, 11:50 AM   #4
diyAudio Member
 
Join Date: Jan 2011
Location: in a small town called Senlis, north of Paris
Hello all and especially Simon.
So, I made a new PCB which is 'better' in IMHO.
here are the results:
1) It is now possible to get easily with the 25k pot the half VCC, just needed to have a stronger VCC: I am now working with 40 Volts. So this part of the problem is solved.
2) the current source still puzzles me: it is impossible to get 2 amps with 0.33 Ohms R4 set. I get only 0.9 A. If I try to lower this one momentarily by paralleling something, the current remains to the 0.9 amps it was !
3) I tried adding a diode in the E circuit of Q5: all the same. there is no tracking of Q5 Vbe.

strangely or not, the whole circuit gets upset (Q3 blocks) if I connect my digital meter around the Q3 gate. When I remove connection, everything gets back but very slowly (due to C4 loading/adjusting I suppose).

So, how to get the Aleph current source to work normally ?

Thanks to all
  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
Visiting and talking with Zen V9... Winding Man Pass Labs 10 23rd September 2011 09:42 PM
Little (or big ?) problem with a Zen V9. gionag Pass Labs 14 21st May 2008 05:06 PM
Zen V9 builder need help sandmarc Pass Labs 2 24th February 2008 07:02 PM
Power supply / zen V9 Phill Pass Labs 5 22nd December 2006 11:41 AM
Zen v4 vs. Zen v9 Kashmire Pass Labs 3 28th February 2006 06:56 PM


New To Site? Need Help?

All times are GMT. The time now is 04:28 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