Go Back   Home > Forums > >
Home Forums Rules Articles diyAudio Store Blogs Gallery Wiki Register Donations FAQ Calendar Search Today's Posts Mark Forums Read

Pass Labs This forum is dedicated to Pass Labs discussion.

F6 Illustrated Build Guide
F6 Illustrated Build Guide
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 5th December 2017, 04:13 PM   #991
Alistair72 is offline Alistair72  United Kingdom
diyAudio Member
 
Join Date: Apr 2007
Location: NW-UK
Default Diagnostic Pics

Iíve attached some pics. Let me know if they arenít clear enough. I have more, I didnít want to swamp the thread with pics.

6L6, thanks in particular to you. Without your guide(s) this would just be a dream.

Al
Attached Images
File Type: jpg 8A641EF0-3107-4CEB-ABE6-979CD9F81EBE.jpg (428.4 KB, 151 views)
File Type: jpg 21C28800-5AA1-414A-BC88-CCC49B5DA9B2.jpg (482.0 KB, 143 views)
File Type: jpeg 4A57127D-45EA-4113-8C5F-B7714D80E6D4.jpeg (858.9 KB, 135 views)
File Type: jpeg 91280ACD-C6C3-4670-B827-561AD91C967E.jpeg (852.7 KB, 128 views)
  Reply With Quote
Old 5th December 2017, 04:33 PM   #992
6L6 is offline 6L6  United States
diyAudio Moderator
 
6L6's Avatar
 
Join Date: Oct 2010
Location: Denver, Colorado
F6 Illustrated Build Guide
Al,

Have you tried to turn down the bias on channel B with the tester in place? It's unlikely you'll hurt anything with it (bulb) connected.

Re-attach the board to the sinks and give it a go. If the bias pot does react properly (I.E., you can get the bulb to dim) than attempt to bias to about 1/4 of the suggested ammount and adjust DC offset to zero. Then remove bulb and measure
  Reply With Quote
Old 5th December 2017, 04:54 PM   #993
Alistair72 is offline Alistair72  United Kingdom
diyAudio Member
 
Join Date: Apr 2007
Location: NW-UK
Quote:
Originally Posted by 6L6 View Post
Al,

Have you tried to turn down the bias on channel B with the tester in place? It's unlikely you'll hurt anything with it (bulb) connected.

Re-attach the board to the sinks and give it a go. If the bias pot does react properly (I.E., you can get the bulb to dim) than attempt to bias to about 1/4 of the suggested ammount and adjust DC offset to zero. Then remove bulb and measure
With tester in place, bias appears to read zero (Measuring across the legs of R2 - the green one just to the right of the cap in the first pic) and P2 does not seem to have any effect - no voltage or dimming of the limiter bulb.

There is a hot dust smell, but I canít locate any hot spot/components.
  Reply With Quote
Old 5th December 2017, 04:56 PM   #994
6L6 is offline 6L6  United States
diyAudio Moderator
 
6L6's Avatar
 
Join Date: Oct 2010
Location: Denver, Colorado
F6 Illustrated Build Guide
Hmmmmm. Ok, that's not right.

Look for poor solder joints, make sure your power connections are 100% proper, and doublecheck that you have no crumbs of metal in the Mosfet insulators.
  Reply With Quote
Old 5th December 2017, 05:28 PM   #995
Alistair72 is offline Alistair72  United Kingdom
diyAudio Member
 
Join Date: Apr 2007
Location: NW-UK
Smile Result!

Quote:
Originally Posted by 6L6 View Post
Hmmmmm. Ok, that's not right.

Look for poor solder joints, make sure your power connections are 100% proper, and doublecheck that you have no crumbs of metal in the Mosfet insulators.
Heated all the joints up again with a hot iron. Sorted. Must have had a duff joint despite them all looking right.

Both sides seem to be working. No LEDs functioning, but that might be down to buying the wrong thing. But both channels start up (individually and together) on the bulb tester with just a brief glow and then it goes off.

Right, now to swap leads and bias 🙂

I shall report back...

Thanks 6L6

Al
  Reply With Quote
Old 5th December 2017, 05:47 PM   #996
6L6 is offline 6L6  United States
diyAudio Moderator
 
6L6's Avatar
 
Join Date: Oct 2010
Location: Denver, Colorado
F6 Illustrated Build Guide
Wonderful news! Report back with results.


Oh, and turn the LED around on the PCBs , they are likely just in backwards
  Reply With Quote
Old 5th December 2017, 06:34 PM   #997
Alistair72 is offline Alistair72  United Kingdom
diyAudio Member
 
Join Date: Apr 2007
Location: NW-UK
And bugger! I think I have fried A.

So B is biased 0.505V and almost 0V offset (it flickers around 0 buy +/- 0.4 mV). The LED works.

I moved to A, in my enthusiasm I forgot to wind back the bias (from my previous attempt to bias it with the limiter in place). It started at about 1.5v and as I was turning it off I noticed a wisp of smoke from the middle, coming up the back of the PCB from Q2 direction. Q2 was hot. As was R1. Both too hot to touch, but cooled quickly.

I have redone all the joints (swapped the LED round) and whilst there centred the bias and offset pots. I have re-tested with with the limiter in place (all good) and now I am getting nothing across R2, zero volts with the power on.

Have I cooked it? I hope not.
  Reply With Quote
Old 5th December 2017, 08:41 PM   #998
fabrice63 is offline fabrice63  France
diyAudio Member
 
fabrice63's Avatar
 
Join Date: May 2015
Location: Frťjus
solder joint must be fully made on both side , not like post 991 .

I tell you this , because it made some issues on my setup

.
  Reply With Quote
Old 7th December 2017, 04:21 PM   #999
Alistair72 is offline Alistair72  United Kingdom
diyAudio Member
 
Join Date: Apr 2007
Location: NW-UK
Default H

Quote:
Originally Posted by Alistair72 View Post
And bugger! I think I have fried A.

So B is biased 0.505V and almost 0V offset (it flickers around 0 buy +/- 0.4 mV). The LED works.

I moved to A, in my enthusiasm I forgot to wind back the bias (from my previous attempt to bias it with the limiter in place). It started at about 1.5v and as I was turning it off I noticed a wisp of smoke from the middle, coming up the back of the PCB from Q2 direction. Q2 was hot. As was R1. Both too hot to touch, but cooled quickly.

I have redone all the joints (swapped the LED round) and whilst there centred the bias and offset pots. I have re-tested with with the limiter in place (all good) and now I am getting nothing across R2, zero volts with the power on.

Have I cooked it? I hope not.
Any tips folks? I neee to get ordering the bits if I am to beat the Xmas post.
  Reply With Quote
Old 7th December 2017, 05:13 PM   #1000
Zen Mod is offline Zen Mod  Serbia
Official Court Jester
diyAudio Member
 
Zen Mod's Avatar
 
Join Date: Jan 2003
Location: ancient Batsch , behind Iron Curtain
F6 Illustrated Build Guide
most likely just new mosfets

check source reistors , just in case
__________________
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


F6 Illustrated Build GuideHide 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

Forum Jump

Similar Threads
Thread Thread Starter Forum Replies Last Post
F5Turbo Illustrated Build Guide 6L6 Pass Labs 333 3rd December 2017 09:39 PM
Aleph J illustrated build guide 6L6 Pass Labs 2257 29th November 2017 06:02 AM
diyAudio Power Supply Circuit Board v3 illustrated build guide 6L6 Power Supplies 615 25th November 2017 03:31 PM
ACA illustrated build guide 6L6 Pass Labs 136 21st August 2017 11:21 PM
BA-3 Amplifier illustrated build guide 6L6 Pass Labs 122 27th July 2017 03:49 AM


New To Site? Need Help?

All times are GMT. The time now is 08:31 AM.


Search Engine Optimisation provided by DragonByte SEO (Pro) - vBulletin Mods & Addons Copyright © 2017 DragonByte Technologies Ltd.
Resources saved on this page: MySQL 14.29%
vBulletin Optimisation provided by vB Optimise (Pro) - vBulletin Mods & Addons Copyright © 2017 DragonByte Technologies Ltd.
Copyright ©1999-2017 diyAudio
Wiki