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.

Build This MoFo!
Build This MoFo!
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 Today, 02:24 AM   #1421
vdi_nenna is offline vdi_nenna  United States
diyAudio Member
 
vdi_nenna's Avatar
 
Join Date: Oct 2000
Location: PA, USA
Build This MoFo! Send a message via Yahoo to vdi_nenna
You try testing with an 8 ohm power resistor on the output?
__________________
I build, therefore I am.
  Reply With Quote
Old Today, 02:25 AM   #1422
e_fortier is online now e_fortier  Canada
diyAudio Member
 
e_fortier's Avatar
 
Join Date: May 2001
Location: Eastern Canada
Build This MoFo!
Is your bias still 2.5A after 1h ?
How about your Dell smps, it’s not overheating?
Short the INPUT and add a 8ohm load.
  Reply With Quote
Old Today, 02:34 AM   #1423
Eric is offline Eric  United States
diyAudio Member
 
Eric's Avatar
 
Join Date: Nov 2000
Location: Central PA, USA
Build This MoFo!
Yep - bias holds pretty steady at 2.5A once things are warmed up. The power brick is rated to deliver 12.3A at 19.5v (total of 240w) and is mildly warm after an hour.

No inputs or outputs are connected. Is this causing it to oscillating it's way into oblivion? I've burned two transistors now...
__________________
My DIY Basement Theater, Aleph-X Amps, Avro Open Baffle Speakers, LDR based BA-3 pre, Pearl II, highly modded Technics SL-1200, F4, M2, a40, several ACAs, FHXL, Tang Band 1772 bass-reflex
  Reply With Quote
Old Today, 02:42 AM   #1424
e_fortier is online now e_fortier  Canada
diyAudio Member
 
e_fortier's Avatar
 
Join Date: May 2001
Location: Eastern Canada
Build This MoFo!
Looks like you didn’t install the 20v zener for Q1
That would help protecting it.
  Reply With Quote
Old Today, 02:48 AM   #1425
Eric is offline Eric  United States
diyAudio Member
 
Eric's Avatar
 
Join Date: Nov 2000
Location: Central PA, USA
Build This MoFo!
No, I didn't install the 20v zener. I have them, but the BoM indicates they are optional and it's not shown in the schematic in Figure 1. Since I didn't find a description of it in the article, I left it out. Mike's image at the start of the thread shows the zener is missing as well.

I don't understand what role the zener serves...
__________________
My DIY Basement Theater, Aleph-X Amps, Avro Open Baffle Speakers, LDR based BA-3 pre, Pearl II, highly modded Technics SL-1200, F4, M2, a40, several ACAs, FHXL, Tang Band 1772 bass-reflex
  Reply With Quote
Old Today, 03:02 AM   #1426
e_fortier is online now e_fortier  Canada
diyAudio Member
 
e_fortier's Avatar
 
Join Date: May 2001
Location: Eastern Canada
Build This MoFo!
The 20v Zener ensures that the max Vgs of the Mosfet (20v)is never above its limit.
See here:

what's the purpose of the zener, mosfet | All About Circuits
  Reply With Quote
Old Today, 03:13 AM   #1427
Eric is offline Eric  United States
diyAudio Member
 
Eric's Avatar
 
Join Date: Nov 2000
Location: Central PA, USA
Build This MoFo!
I have a single IRFP250 left. I'll install the zener and test with my 8R dummy load and see what happens... I still don't understand how voltage can rise above 20v with a 19.5v PSU and no signal present.

I'll pick it up again tomorrow night and see how things go.
__________________
My DIY Basement Theater, Aleph-X Amps, Avro Open Baffle Speakers, LDR based BA-3 pre, Pearl II, highly modded Technics SL-1200, F4, M2, a40, several ACAs, FHXL, Tang Band 1772 bass-reflex
  Reply With Quote
Old Today, 03:18 AM   #1428
e_fortier is online now e_fortier  Canada
diyAudio Member
 
e_fortier's Avatar
 
Join Date: May 2001
Location: Eastern Canada
Build This MoFo!
Hopefully by tomorrow someone will come with an explanation

I would test with the input shorted.
  Reply With Quote

Reply


Build This MoFo!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

Forum Jump

Similar Threads
Thread Thread Starter Forum Replies Last Post
Adapt Polk Audio R20 for Classix II build or build box? unpredictableape Multi-Way 3 3rd April 2017 07:25 AM
Power Acoustik MOFO 10, need box dimensions Spuddd Subwoofers 2 5th January 2017 10:46 AM
LJM MX50-SE - Build Log Gallery & My Build Progress dakku Solid State 3 28th October 2016 08:49 AM
Do i need to build main supply (240v) filter?Or build power distribution? thomgun_lc Chip Amps 9 16th September 2005 09:52 AM
Power Acoustik MOFO-10 Sub subwo1 Car Audio 1 24th October 2003 08:12 AM


New To Site? Need Help?

All times are GMT. The time now is 03:44 AM.


Search Engine Optimisation provided by DragonByte SEO (Pro) - vBulletin Mods & Addons Copyright © 2018 DragonByte Technologies Ltd.
Resources saved on this page: MySQL 15.00%
vBulletin Optimisation provided by vB Optimise (Pro) - vBulletin Mods & Addons Copyright © 2018 DragonByte Technologies Ltd.
Copyright ©1999-2018 diyAudio
Wiki