Pearl Two - Page 111 - 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 6th December 2011, 04:23 PM   #1101
nar is offline nar
diyAudio Member
 
nar's Avatar
 
Join Date: Apr 2002
Location: near the sea
Quote:
Originally Posted by richluvsound View Post
I have been checking voltages against Schematic .... ?

I have a flickering LED on one board .Measuring is nigh on impossible ? I have tried tracing it back ,but I'm at the edge of my knowledge .

On the other board I have a drop on Q3 ... I should be reading 10 VDC and I'm getting 1.3 VDC


Also , setting P1 ? I have + on pin and - on PAD ground is this correct , If so, why is my meter all over the place ?

HELP PLEASE ?

Rich
Please do some measures again and post. Rails, and other parts.
I assume you talk about led Vref so I also assume you talk about Pearl II

Best,

nAr
__________________
"... Audio needs the thinnest wire ..." Rowan McCombe ... I hear it !!!
"Just 'cause they can't hear or sense it themselves doesn't mean you can't !" Allen Wright Allen was right ...

Last edited by nar; 6th December 2011 at 04:31 PM.
  Reply With Quote
Old 6th December 2011, 06:02 PM   #1102
diyAudio Member
 
richluvsound's Avatar
 
Join Date: Sep 2010
Location: LONDON
Hi Nar ,

just been on skype with 6L6 . We took all the measurements . He will
post shortly for your input . ME ? .... I'm just doing as I'm told !

Rich
  Reply With Quote
Old 6th December 2011, 06:04 PM   #1103
nar is offline nar
diyAudio Member
 
nar's Avatar
 
Join Date: Apr 2002
Location: near the sea
OK. I will check the board from time to time

nAr
__________________
"... Audio needs the thinnest wire ..." Rowan McCombe ... I hear it !!!
"Just 'cause they can't hear or sense it themselves doesn't mean you can't !" Allen Wright Allen was right ...
  Reply With Quote
Old 6th December 2011, 06:34 PM   #1104
wayne is offline wayne  United States
diyAudio Member
 
Join Date: Jan 2002
Location: Northern California
Default Pearl 2 Voltages

Corrected voltages on the schematic. 6L6 pointed out I had a negative voltage exceeding the supply.
Attached Files
File Type: pdf Pearl2Votages1.pdf (45.9 KB, 202 views)
  Reply With Quote
Old 6th December 2011, 06:51 PM   #1105
Zen Mod is offline Zen Mod  Serbia
diyAudio Member
 
Zen Mod's Avatar
 
Join Date: Jan 2003
Location: ancient Batsch , behind Iron Curtain
programmed current for positive shunt reg : 60mA

programmed current for negative shunt reg : 30mA

per channel

back'o'napkin calc of exact Iq , per channel :
positive leg : 4 x 5mA + 3mA + 2 x 1mA +10mA= 34mA
negative leg : 2mA + 4,6mA + 10mA = 16,6mA

edit : presuming that each input Jfet is in 5mA ballpark
__________________
my Papa is smarter than your Nelson !
clean thread; Cook Book;PSM LS Cook Book;Baby DiyA ;Mighty ZM's Bloggg;Papatreasure;Papa... by Mighty ZM

Last edited by Zen Mod; 6th December 2011 at 06:54 PM.
  Reply With Quote
Old 6th December 2011, 07:51 PM   #1106
6L6 is offline 6L6  United States
diyAudio Member
 
6L6's Avatar
 
Join Date: Oct 2010
Location: Denver, Colorado
After a long skype conversation with Rich and a quick phone call to our esteemed Mr. Colburn, it's a good guess that Q2 (the ZVP3310) is inoperative.

However, as I am sitting here typing this, I got an Email from Rich saying that he replaced Q2 with a new one and the measurements are basically the same...

The rails are fine, at + and- 24v. There is a little low voltage around Q3, 7.9 base / 7.3 collector / 7.2 emitter .

The big problem are the voltages around Q2 -- they are +23 drain / +19v gate / -23.8v source. This is not good, as there should be zero volts (or close) on the source.

Also, the measurements around Q11 are -23v base / -23.8v collector / -23.9v emitter.
  Reply With Quote
Old 6th December 2011, 09:13 PM   #1107
wayne is offline wayne  United States
diyAudio Member
 
Join Date: Jan 2002
Location: Northern California
Do we have good grounding on this unit? Is C9 in place? If it is oscillating measurement will be difficult.
  Reply With Quote
Old 6th December 2011, 09:38 PM   #1108
nar is offline nar
diyAudio Member
 
nar's Avatar
 
Join Date: Apr 2002
Location: near the sea
I also think about an oscilation issue. If pot can't be adjusted it looks like a symptom.
The ZVP wouldn't need compensation cap, it can even make the circuit oscilate in some cases

Best,

nAr
__________________
"... Audio needs the thinnest wire ..." Rowan McCombe ... I hear it !!!
"Just 'cause they can't hear or sense it themselves doesn't mean you can't !" Allen Wright Allen was right ...
  Reply With Quote
Old 6th December 2011, 09:56 PM   #1109
6L6 is offline 6L6  United States
diyAudio Member
 
6L6's Avatar
 
Join Date: Oct 2010
Location: Denver, Colorado
I didn't ask if C9 is installed.

The PSU is grounded to the mains as shown in the article, through the bridge. The Pearl circuit board is not in a case, nor are the signal leads hooked up.

Would oscillation cause the negative rail to appear at the source of Q2?

Should the input be grounded for testing? And/or the output?
  Reply With Quote
Old 6th December 2011, 09:59 PM   #1110
diyAudio Member
 
richluvsound's Avatar
 
Join Date: Sep 2010
Location: LONDON
C9 is installed .... !
  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
Another diy-pearl... lykkedk Pass Labs 18 15th June 2007 04:44 PM
ono or pearl PCB's mantisory Pass Labs 1 28th September 2006 11:12 PM
Pearl need help dzkh63 Pass Labs 1 26th September 2006 03:16 PM
WTB: Pearl PCB aire Pass Labs 1 26th February 2006 10:51 AM


New To Site? Need Help?

All times are GMT. The time now is 09:00 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