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.

Broken Sony TA-N330ES (2SC2921 Transistor)
Broken Sony TA-N330ES (2SC2921 Transistor)
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 29th May 2010, 09:20 PM   #1
qtoche is offline qtoche
diyAudio Member
Join Date: May 2010
Default Broken Sony TA-N330ES (2SC2921 Transistor)

Well, I can't say that I know much of anything about High end stereo amplifiers or electronics, but I am trying to get into it a little and started off with a used amp for my home set up. I purchaced this amp for $125 at a yard sale, knowing that it was mid to early 90's but that it would be much better than any new equipment that I could afford. Unfortunately it does not work, the protect light is on. I had looked over the boards and caps before I purchaced it and all looked very good, but I missed a burnt out transistor. (2SC2921) I don't see anything else that is damaged so I am planning on ordering this transistor and replacing it. Is it common for these transistors to fail and not damage anything else? Also I need to make sure that this is the same transistor as what I have. Mine is labeled
Sanken 2SC2921 with 19f below that line. The one I am looking to purchace is labeled 2SC2921 with an 82p below that line : Sanken Sanken Transistor Mt200 160v 15A 150w BCE | SANKEN | Sanken

I don't know what the 19f or 82p mean...

Hopefully I can get this amplifier back up and running.

Thanks, Neil
  Reply With Quote
Old 29th May 2010, 11:49 PM   #2
ilimzn is offline ilimzn  Croatia
diyAudio Member
Join Date: Feb 2005
Location: Zagreb
Rhis is one of a pair (or multiple pairs) of output transistor(s), a NPN part. It's complementary sounterpart is the 2SA1215 if memory serves me right.
When one in a complementary pair fails, it is almost certain the other is also damaged even though it might test good using the usual simple transistor test.
Things to check:
1) There is usually a small value (fraction of an ohm) large size (2-5W) resistor connected between the emitter and the output of the amp (prior to the protection relay). Check that it is not open on all output transistors in that channel.
2) There is usually a small value low wattage (few ohms) resistor in the base circuit. Check that it is not open on all output transistors in that channel.
3) Check driver transistors (usually one pair of smaller types in TO220 case, possibly mounted on small separate heatsinks)

The usual procedure to do this right is to prevejtively replace the emitter resistors, all output transistors in the channel, and the driver transistors, also base stopper resistors if present. It sounds like an unreasonable investment if only one transistor seems to have failed, but it saves you multiple repairs and associated possibility of PCB and mechanical damage, as the whole output circuit operates in concert, so if one transistor has gone dead (which is always due to some kind of abuse), the other parts have been abused as well. It's only that the one that failed managed to fail completely before the others did. If you leave them in there, expect sudden 'inexplicable' failures and the very real possibility of further parts failing due to operation outside of the normal conditions during repeated failures.

One more thing - buy parts from reputable suppliers. These transistors are very often faked and the fakes are either complete rubbish and will go up in smoke taking other parts with them immediately or shortly after turn-on, or are not up to spec, so even if you get an operating amplifier, it's performance will not be as designed and intended.
  Reply With Quote
Old 30th May 2010, 12:52 AM   #3
nigelwright7557 is offline nigelwright7557  United Kingdom
diyAudio Member
nigelwright7557's Avatar
Join Date: Apr 2008
Location: Carlisle, England
Transistors rarely go for no reason.

Could have been a short on the output.
Possibly a bias problem causing the output transistors to short out the power supplies.

What I do with blown output transistors is remove the lot and wire the VAS output back into the LTP. Then I power up the amp (without a speaker) and see what bias voltage and DC offset I am getting.

Only when I am satisfied the driver stage is OK do I consider putting output transistors back in, even then I only put one pair in to start with.

This strategy has saved a lot of heartache with repeat blown output transistors,
PCBCAD51 pcb design software. 2018 version out now with lower prices >> http://www.murtonpikesystems.co.uk
  Reply With Quote
Old 30th May 2010, 02:07 AM   #4
Ian Finch is offline Ian Finch  Australia
diyAudio Member
Join Date: Apr 2010
Location: Coffs Harbour, NSW
Nigel, I have heard of this technique before but it is a very unspecific instruction, to the inexperienced, to say "wire the VAS back to the Long Tailed Pair".
I for one (and I expect qtoche) would appreciate a little flesh on the bones of where on the LTP this point might be and with what, if any additional components or precautions.
In ignorance but with respect,
If only I had listened....
  Reply With Quote


Broken Sony TA-N330ES (2SC2921 Transistor)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
Sony TA-F60 CrazzyAbtTubes Solid State 6 18th October 2009 10:53 PM
Sony TA-F55 MassiAudio Solid State 7 18th January 2008 12:46 PM
Sony TA-P717 doomsweek Parts 0 18th December 2007 11:48 AM
Sony TA-N1 and TA-NR1, how do they sound? lumanauw Solid State 0 28th November 2006 01:51 AM
FS: Sony "Esprit" TA-E901 and TA-N901 pre and power amp MJR Swap Meet 1 6th December 2003 07:55 PM

New To Site? Need Help?

All times are GMT. The time now is 03:14 AM.

Search Engine Optimisation provided by DragonByte SEO (Pro) - vBulletin Mods & Addons Copyright © 2018 DragonByte Technologies Ltd.
Resources saved on this page: MySQL 15.79%
vBulletin Optimisation provided by vB Optimise (Pro) - vBulletin Mods & Addons Copyright © 2018 DragonByte Technologies Ltd.
Copyright ©1999-2018 diyAudio