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

Solid State Talk all about solid state amplification.

Luxman 5M21
Luxman 5M21
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 18th September 2017, 01:29 PM   #101
rfitts46 is offline rfitts46  United States
diyAudio Member
 
Join Date: Jan 2014
Location: New Hampshire
carlmart,


quote [have you checked the junction between the FET and the cascode transistors]


no I have not. are we talking about this junction
Attached Images
File Type: png dml module.png (75.6 KB, 25 views)
  Reply With Quote
Old 18th September 2017, 02:04 PM   #102
carlmart is offline carlmart  Brazil
diyAudio Member
 
Join Date: Mar 2001
Location: Brazil
Yes, that's it. At least you should know if the oscillation comes from the FET.

The oscillation I got on my simulation was cured in the driver's stage. Perhaps you might try it.
  Reply With Quote
Old 18th September 2017, 02:37 PM   #103
rfitts46 is offline rfitts46  United States
diyAudio Member
 
Join Date: Jan 2014
Location: New Hampshire
QUOTE [Yes, that's it. At least you should know if the oscillation comes from the FET. ]


carlmart, Wouldn't oscillation be seen there because of the oscillation being supplied back to the input card via feedback.


Couldn't the oscillation still be occurring downstream from the FET and the oscillation being supplied to the input of the FET from the feedback?


As mentioned the DML modules have been swapped and the oscillation did not follow the DML module.

Last edited by rfitts46; 18th September 2017 at 02:40 PM.
  Reply With Quote
Old 18th September 2017, 04:12 PM   #104
carlmart is offline carlmart  Brazil
diyAudio Member
 
Join Date: Mar 2001
Location: Brazil
OK. This is the complete original 5M21 schematic, included parts inside the DML.

The other schematic shows, in red, what cured the first stage oscillation.

You may try it and see if it works for you.

Start with isolating the driver resistors from the NFB and add the 10uF cap. That should be easy to implement, with just one retrofittable track mod.

For lowering the resistors to 4.7, you can just add 10R resistors on the copper side.
Attached Images
File Type: jpg Luxman 5M21. faxtory schematic_one channel.jpg (700.5 KB, 18 views)
File Type: jpg Luxman 5M21. faxtory schematic_osc mods.jpg (830.2 KB, 18 views)
  Reply With Quote
Old 18th September 2017, 05:10 PM   #105
carlmart is offline carlmart  Brazil
diyAudio Member
 
Join Date: Mar 2001
Location: Brazil
Forgot to say that it cured the oscillation on the LTSpice simulation, of course.
  Reply With Quote

Reply


Luxman 5M21Hide 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
luxman help orsen Solid State 2 2nd July 2014 11:32 AM
Luxman C-1000 Carlosraj Solid State 5 2nd March 2012 07:38 AM
Luxman joelfl Solid State 3 18th August 2010 10:05 AM
Luxman D-404 Rob M Digital Source 0 21st November 2004 07:44 PM
5M21 Service Manual Needed NickC Solid State 0 31st July 2003 10:16 AM


New To Site? Need Help?

All times are GMT. The time now is 08:09 PM.


Search Engine Optimisation provided by DragonByte SEO (Pro) - vBulletin Mods & Addons Copyright © 2017 DragonByte Technologies Ltd.
Resources saved on this page: MySQL 15.00%
vBulletin Optimisation provided by vB Optimise (Pro) - vBulletin Mods & Addons Copyright © 2017 DragonByte Technologies Ltd.
Copyright ©1999-2017 diyAudio
Wiki