troubleshooting zv9 - 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 13th April 2007, 04:33 PM   #1
diyAudio Member
 
neil_kaye's Avatar
 
Join Date: Dec 2005
Location: San Francisco
Default troubleshooting zv9

I have actually decided to strip and rebuild the entire channel but for my own edification i was hoping someone might offer up some advice as to what might be causing the following problem:

1. DC output from rectified transformer is 52V (on my other channel i am getting 48V). Is 52 VDC to high?
2. I get a very distorted sound out of the speaker and with hardly any volume. You can almost hear the beat of the music but that's about it.
3. I thought i had blown the JFET but i replaced that and i still have the same problem.
4. The amp did work at one stage and then something blew / popped ( i think i had shorted out my MOSFET's. Before it blew i had trimmed the DC to read half of the input. Once it had blown there was no voltage difference where i had measured to trim the DC. So i replaced the JFET and it's adjacent MOSET and now i have a voltage but i had to turn the trimpot way down to get it back up.

What do you think the problem is?

As i said i am sick of mucking around with this so i am going to rebuild the entire board. Do you think i need to rebuild the PSU?
  Reply With Quote
Old 13th April 2007, 04:43 PM   #2
cviller is offline cviller  Denmark
diyAudio Member
 
cviller's Avatar
 
Join Date: Dec 2005
Location: Copenhagen
Blog Entries: 2
Does it get hot? If not, then your psu is not loaded and it can easily climb a few volts higher than under normal operation.

Try to measure as many voltages and compare them to the healthy channel. If you find a difference, you'll be able to get a better idea of where to look for burned components.
  Reply With Quote
Old 13th April 2007, 04:52 PM   #3
diyAudio Member
 
neil_kaye's Avatar
 
Join Date: Dec 2005
Location: San Francisco
It does not get hot at all.. which as you stated means it is not loaded
What are the components that can blow?
  Reply With Quote
Old 13th April 2007, 05:00 PM   #4
cviller is offline cviller  Denmark
diyAudio Member
 
cviller's Avatar
 
Join Date: Dec 2005
Location: Copenhagen
Blog Entries: 2
With some voltages I might be able to give better guesses, but I think you should look at Q5 and D1 - pull them out at test them.

Check if polarity of C4 and C3 are turned correctly and that they are not burned.
  Reply With Quote
Old 13th April 2007, 05:08 PM   #5
diyAudio Member
 
neil_kaye's Avatar
 
Join Date: Dec 2005
Location: San Francisco
thanks i will give it a try.
A question about measuring voltages. What point on the board should i use to establish the ground and which the live. I imagine one of the points would be at the component being tested?
  Reply With Quote
Old 13th April 2007, 05:10 PM   #6
cviller is offline cviller  Denmark
diyAudio Member
 
cviller's Avatar
 
Join Date: Dec 2005
Location: Copenhagen
Blog Entries: 2
You should use gnd as reference for all voltages. Clamp you meters gnd wire on the leg of R1 which is connected to R7.
  Reply With Quote
Old 13th April 2007, 10:57 PM   #7
Zen Mod is offline Zen Mod  Serbia
diyAudio Member
 
Zen Mod's Avatar
 
Join Date: Jan 2003
Location: ancient Batsch , behind Iron Curtain
look-ZV9 have sooooo much parts................

pull up (solder them out ) all active devices;
same with all diodes;
check each resistor ; if in doubt-unsolder one leg from circ and then measure.

change what is burned

put new semis in

re-set what you need
__________________
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
  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
need help troubleshooting an amp emremeydan Solid State 12 28th January 2008 11:16 PM
Zen V8 Troubleshooting moe29 Pass Labs 13 20th March 2006 04:44 PM
Help troubleshooting Zen V4 ophilip Pass Labs 18 11th February 2006 01:39 AM
help troubleshooting this diy pre-amp zobsky Tubes / Valves 21 3rd November 2003 12:06 AM
Troubleshooting MikeBike Solid State 3 30th September 2001 05:19 PM


New To Site? Need Help?

All times are GMT. The time now is 07:41 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