pearl, q4 no voltage - 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 20th January 2009, 01:58 PM   #1
diyAudio Member
 
Join Date: Dec 2006
Default pearl, q4 no voltage

unfortunately one channel of my pearl phono stage stopped working and needs some help. First aid indication:

No voltage on Q4 (the ztx 450) next to the 2sk 389. There is a "control point" were I should measure 13,8 V or so. Any hint what that points to?

help is highly appreciated
stefan
  Reply With Quote
Old 20th January 2009, 02:29 PM   #2
diyAudio Member
 
Join Date: Dec 2006
It´s not exatly zero, Imeasured 750 mV.
stefan
  Reply With Quote
Old 21st January 2009, 05:30 PM   #3
cviller is online now cviller  Denmark
diyAudio Member
 
cviller's Avatar
 
Join Date: Dec 2005
Location: Copenhagen
Blog Entries: 2
What is the voltage on either pin of R8 in reference to gnd?

You can measure the 13.6V on the emitter of Q4. The emitter is the one which is not the middle pin and not connected to R14...
  Reply With Quote
Old 24th January 2009, 07:37 PM   #4
diyAudio Member
 
Join Date: Dec 2006
hi cvi,
late answer.
on R8 i measured 28,1 and 28,6 to gnd.
the same points at the working channel give 28,4 and 28,7. So seems to be the same.
stefan
  Reply With Quote
Old 24th January 2009, 09:54 PM   #5
cviller is online now cviller  Denmark
diyAudio Member
 
cviller's Avatar
 
Join Date: Dec 2005
Location: Copenhagen
Blog Entries: 2
My best guess is that you have burned the 2sk389 (not your fault, but a lot of people have had this problem).

If you don't think that is the problem. Please take the schematics and put all your measurements on the schematics (you can do this is in paint), then I might be able to point you to the problem.
  Reply With Quote
Old 24th January 2009, 10:25 PM   #6
diyAudio Member
 
Join Date: Dec 2006
hey cviller, that is veery kind of you. When Leela finished, I´ll also have a look at the schematics and report

[IMG]Click the image to open in full size. Click the image to open in full size.[/IMG]
  Reply With Quote
Old 24th January 2009, 10:27 PM   #7
diyAudio Member
 
Join Date: Dec 2006
I heard that it is wise to split the source resistors. If i can find another 2sk 389 i´d try it this way.
stefan
  Reply With Quote
Old 24th January 2009, 10:51 PM   #8
cviller is online now cviller  Denmark
diyAudio Member
 
cviller's Avatar
 
Join Date: Dec 2005
Location: Copenhagen
Blog Entries: 2
You can easily use two 2sk170, but you'll have to match them (idss).

Quote:
Here's to us poor schmoes, working for the man. Although she is a hot, sexy female man.
  Reply With Quote
Old 24th January 2009, 11:08 PM   #9
diyAudio Member
 
Join Date: Dec 2006
yes, of course, i read that somewhere with the sk 170 substitution. and i got some here
but how to do that will be my tomorrow´s research. huhu, i dip my feet n electronics
tnx,
stefan
  Reply With Quote
Old 26th January 2009, 03:37 PM   #10
diyAudio Member
 
Join Date: Dec 2006
cviller, thanx again for offering your help.
After a friend of mine also supposed that the double fet is gone, i was offensive and changed it with two 2sk 170. I matched them with a 9V battery and a 10Ohm resistor.
Than i split the source resistors (two 20 Ohms) and everything is fine now. soundstage still in the middle.

When i plugged it in there still was no sound on the left channel, but it turned out that the cable was broken. (but the channel was also )

tnx
stefan
  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
Pearl: replace zener D1 with voltage divider? h_a Pass Labs 14 22nd February 2007 01:43 PM
WTB: Pearl PCB aire Pass Labs 1 26th February 2006 11:51 AM
yet another(different) pearl voltage problem detritus Pass Labs 3 1st April 2005 03:56 AM
Pearl voltage problem dzkh63 Pass Labs 6 4th March 2005 04:10 AM
Pearl input voltage difference Zappa Pass Labs 1 6th April 2003 09:15 PM


New To Site? Need Help?

All times are GMT. The time now is 07:32 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