Need switching supply repair help (antique) - diyAudio
Go Back   Home > Forums > General Interest > Everything Else

Everything Else Anything related to audio / video / electronics etc) BUT remember- we have many new forums where your thread may now fit! .... Parts, Equipment & Tools, Construction Tips, Software Tools......

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 20th May 2004, 01:39 AM   #1
SY is offline SY  United States
diyAudio Moderator
 
SY's Avatar
 
Join Date: Oct 2002
Location: Chicagoland
Blog Entries: 1
Default Need switching supply repair help (antique)

OK, I'm pretty clueless about switching supplies. And the unit I'm using as a crossover has one, albeit an antique. It's built into a Berning TF-10 preamp. Schematic is here.

The supply doesn't want to start up; when I flick it on, I can see the LED start to fire, then poop out immediately. I replaced the high speed diode called out in the "parts likely to fail," with no help. Now, here's the funny thing- I replaced the 2N2222 (also called out in the "parts likely to fail" section) with a plastic version (PN2222?) and the supply started up. It also screeched like an owl. If I shut the preamp down and plug the old 2N2222 back in fairly quickly, it starts up and runs quietly. If the preamp has sat around for a while and I stick in the old 2N2222, another 2N2222, or a 2N2222A, the supply won't start up.

Before I pull and replace the HV TO3 jobs, any suggestions as to a likely culprit here? If it helps, the deterioration was a slow one- for a while, the unit would start up if I pulled the tubes out, but now it doesn't even do that.
__________________
You might be screaming "No, no, no" and all they hear is "Who wants cake?" Let me tell you something: They all do. They all want cake.- Wilford Brimley
  Reply With Quote
Old 20th May 2004, 11:40 AM   #2
Netlist is offline Netlist  Belgium
diyAudio Moderator Emeritus
 
Netlist's Avatar
 
Join Date: Jan 2003
Hi SY
This could be a tough one.
What I usually do without even trying to understand how this whole thing works is changing caps in the primary section.
I can see C705/6 and perhaps also C703 apart from the ones I missed.
I would check some resistors like R706 and the two-watters.
Next are the caps in the secondary.
If that doesn't help I usually stop in commercial applications.
Not with antique...
There is of course the possibility of leaky zeners and transistors.
That's why it could be a tough one.

Change the caps first!!

/Hugo
  Reply With Quote
Old 20th May 2004, 12:12 PM   #3
SY is offline SY  United States
diyAudio Moderator
 
SY's Avatar
 
Join Date: Oct 2002
Location: Chicagoland
Blog Entries: 1
Default caps

Hugo, thanks. Great minds think alike- that was the first thing I did!
__________________
You might be screaming "No, no, no" and all they hear is "Who wants cake?" Let me tell you something: They all do. They all want cake.- Wilford Brimley
  Reply With Quote
Old 20th May 2004, 02:00 PM   #4
Netlist is offline Netlist  Belgium
diyAudio Moderator Emeritus
 
Netlist's Avatar
 
Join Date: Jan 2003
SY
Next thing I would try is disconnect secondaries.
And perhaps load them with higher ohmic values compared to real life situation.

/Hugo - Thinks SY needs greater "Technical minds"
  Reply With Quote
Old 20th May 2004, 03:12 PM   #5
moamps is offline moamps  Croatia
diyAudio Member
 
Join Date: Oct 2002
Location: Croatia
Hi,

few ideas:

Pn2222 has diferent pinning than 2n2222.
Measure voltage on C709; can be around 100V.
Check D714, 711, replace C707, 708, C 705, C706 with new ones.

Regards
  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
Antique Electric Supply wicked1 Tubes / Valves 14 11th April 2008 09:21 AM
Antique Electronic Supply Cambe Tubes / Valves 3 26th May 2006 11:43 PM
citcuit for switching. supply partyjups Solid State 2 27th December 2001 02:26 PM
switching power supply? partyjups Solid State 1 6th October 2001 12:44 PM


New To Site? Need Help?

All times are GMT. The time now is 03:45 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