Updating old power transistors - diyAudio
Go Back   Home > Forums > Amplifiers > Solid State
Home Forums Rules Articles diyAudio Store Gallery Wiki Blogs Register Donations FAQ Calendar Search Today's Posts Mark Forums Read

Solid State Talk all about solid state amplification.

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
Thread Tools Search this Thread
Old 20th August 2002, 06:36 AM   #1
diyAudio Member
Join Date: May 2002
Default Updating old power transistors

My old Naim 160 power amp uses BDY56 (TO3) output transistors. Can I update them with better modern ones such as the Toshiba 2SC5200( I can fit (TO3-P in place of TO3) . Would they be a direct swop or is there anything else to consider?
  Reply With Quote
Old 20th August 2002, 08:28 AM   #2
diyAudio Member
jan.didden's Avatar
Join Date: May 2002
Location: The great city of Turnhout, BE
Blog Entries: 8
Default Updating power transistors

One thing to look out for is the bandwidth of the replacement transistors. *** far as I recollect the BDY's are not very wideband, so replacing them with the Toshiba's may lead to oscillations and you would have to adjust the compensation - not for the faint at heart!

Jan Didden
  Reply With Quote
Old 20th August 2002, 10:46 AM   #3
diyAudio Member
Join Date: Feb 2002
Location: Germany
A faster output transistor may give you local oscillations, especially with complex loads. Cure: base series resistors (about 10 R) or ferrite beads on the base leads, as close to the transistor case as possible.

Loop oscillations occur if the output stage is too slow, i.e. introduces too much phase lag. Faster output transistors will reduce the phase lag, so there should be no problem. At the same time, they might increase the gain bandwidth, so at the now higher frequency there may be an acerbacated phase lag problem. You should try this also with capacitive loading etc.

Essential for this kind of work are an oscilloscope and a power supply with current limiting (electronic, resistors or some very fast blowing fuses).

  Reply With Quote
Old 20th August 2002, 05:35 PM   #4
diyAudio Member
Join Date: May 2002
Thank you. Without an oscilloscope how can I identify any problems? Will I be able to hear them?
  Reply With Quote
Old 24th August 2002, 02:12 PM   #5
diyAudio Member
Join Date: Jun 2001
Location: Flanders, Belgium
I hope this helps
Attached Images
File Type: jpg bdy56.jpg (48.7 KB, 244 views)
  Reply With Quote
Old 24th August 2002, 04:44 PM   #6
Join Date: Dec 2001
Location: Zamboanga, City of Flowers, Mindanao
Send a message via Yahoo to Elso Kwak
Lightbulb Replacement for BDY56

Hi Hifileslie,
MJ21194 would be a excellent choice, from www.onsemi.com They are TO-3.
  Reply With Quote


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
Updating Onkyo DX-706? Henrik Digital Source 39 21st May 2012 08:13 AM
updating Tachometer circuit? Burnedfingers Everything Else 3 22nd September 2008 06:43 AM
JBL - L300 mods/updating? Cobra2 Multi-Way 14 3rd April 2007 12:04 PM
Vintage Goodmans updating advice? phimor Multi-Way 3 4th January 2006 09:41 AM
SGS power transistors hifiboy Solid State 0 4th October 2004 07:44 AM

New To Site? Need Help?

All times are GMT. The time now is 10:02 PM.

vBulletin Optimisation provided by vB Optimise (Pro) - vBulletin Mods & Addons Copyright © 2017 DragonByte Technologies Ltd.
Copyright 1999-2017 diyAudio

Content Relevant URLs by vBSEO 3.3.2