Fixing old gear / Transistor problems - diyAudio
Go Back   Home > Forums > Design & Build > Parts

Parts Where to get, and how to make the best bits. PCB's, caps, transformers, etc.

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 8th February 2003, 07:40 PM   #1
OliverD is offline OliverD  Germany
diyAudio Member
 
OliverD's Avatar
 
Join Date: Nov 2002
Location: Germany
Default Fixing old gear / Transistor problems

Hello,

when fixing amplifiers, I often encounter the problem that many transistors widely used in old gear are now out of production. Often they are available somewhere but the probability of getting counterfeit devices is quite high. That's why I always stock some standard parts like BC550 / BC560, BD139, BD140, MJE340, MJE350 for driver and input stages and a collection of power devices in various cases.

However, when fixing vintage high end amplifiers, I don't like the idea of substituting those cheap "one for all" transistors.

As it is hard to find more than polarity, Pd, Vce and ft data of old transistors, I'd like to ask the more experienced here on the forum what their suggestions for proper replacements would be:

original -> replacement

2SK240 / 2SJ75 -> 2SK389 / 2SJ109 (???)
(Didn't find any datasheet for Dual JFETs)

2SC3281 / 2SA1302 -> 2SA1987 / 2SC5359
(This should work fine IMHO)

2SK213 / 2SJ76 -> IRF610 / IRF9610 (???)

2SA1142 / 2SC2682 -> ???

2SA1145 / 2SC2705 -> ???

Does anyone have datasheets of those old devices? What modern devices would you suggest as a drop-in replacement?

Thank you!
  Reply With Quote
Old 8th February 2003, 10:06 PM   #2
diyAudio Member
 
EchoWars's Avatar
 
Join Date: Dec 2002
Location: Left of the Dial
Most transistors nowadays are quieter and can handle more power, and have better gain than the old stuff. For the most part, there are good reasons why a component was obsoleted.

For instance, I have actually had to replace a few 2SA1142's in an amp recently. I stuck in a 2SB649A and forgot about it (the 649A is Vceo 160V whereas the 1142 is Vceo 180V, in my application it didn't matter).

On a slightly different matter, I notice your nick "AMT-freak". Posted a question in the speaker forum regarding newer Heil's that I'd hope you'd take a look at.

Air Motion Transformers (Heil's) and New Diaphragms
  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
Fixing the R30 bjackson Multi-Way 3 16th May 2010 06:10 AM
Need some help fixing this amp mazeroth Solid State 1 13th May 2008 03:04 AM
Can bias transistor mount on top(body) of output transistor?? Leolabs Solid State 23 16th February 2008 12:35 AM
Need Help Fixing an old NAD 304 li_gangyi Solid State 14 8th December 2004 07:59 PM
Help! Fixing Amp. shajan Solid State 20 29th May 2004 08:06 AM


New To Site? Need Help?

All times are GMT. The time now is 10:47 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