Problem with Totem Pole Amp - 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 23rd January 2013, 03:02 PM   #1
diyAudio Member
Join Date: Nov 2011
Default Problem with Totem Pole Amp

Hello and please forgive the long post tha follows.

I recently built one channel of Randy Slone's Totem Pole design (the one that can be found in his book, Fig. 6-21). When trying to test it, I notice that the output (with or without load) will start from a relatively high positive voltage, then slowly fall to zero before suddenly going to the negative rail. An then it slowly returns to the positive rail before doing the same thing over and over again.

The very first time I connected a power supply to it (not the actual power supply, but a smaller one for the purposes of testing) one of the resistors in the VA protection circuit (R28 for those of you that may have the schematic) gave out some smoke, but hasn't been destroyed (I assume, since it still measures the correct value). I have tested for a short circuit at the output but couldn't find one. I also tried to test the transistors for a short circuit between their leads but there isn't any (is that the indication that one has been fried?).

I'm currently thinking that the feedback loop is broken somewhere but I haven't found anything as of yet. I would greatly appreciate any ideas.
  Reply With Quote
Old 23rd January 2013, 06:59 PM   #2
diyAudio Member
east electronics's Avatar
Join Date: Jan 2006
Location: Athens GREECE
Is posting schematic an option ?
that can either be latching or oscillation
Of course it might also be a construction error
  Reply With Quote
Old 24th January 2013, 07:35 PM   #3
diyAudio Member
Join Date: Nov 2011
This is the best quality schematic I could find. The resistor in red is the one that almost burnt.
Attached Images
File Type: jpg problem.jpg (129.5 KB, 129 views)
  Reply With Quote
Old 24th January 2013, 09:17 PM   #4
amptech is offline amptech  Scotland
diyAudio Member
Join Date: Jan 2009
Location: Glasgow
Send a message via MSN to amptech
If its burnt change it out, for testing this circuit the s/c protection can be removed also this type of protection has ref point to the supply rails..

Check each part of this circuit on a lower ht and to save the any damage to the MOSFET's just leave one pair in. I've got this book also and will look over things..

Regards. A.
  Reply With Quote
Old 25th January 2013, 09:16 AM   #5
diyAudio Member
Join Date: Nov 2011
Thanks all for your help. The resistor hasn't really burnt, I tested it with an Ohmmeter and it measures just fine.

Am I right to assume that a destroyed transistor will have (some of) its leads short-circuited? Because if that's the case, then there is no problem there either. I might post some pics of my amp later, in case someone can spot a construction error.
  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
Slones Totem Pole Design goodlife Solid State 17 3rd July 2014 07:57 AM
Randy Slone Zus Audio Totem-Pole Build needs 12V trigger tjencks Solid State 14 10th December 2012 01:50 PM
Totem-Pole OTL with 6c33c tubes and 0.079 % THD at 20 Watt gkn202 Tubes / Valves 35 21st September 2011 11:41 PM
Spud-Assist: Totem-Pole Current-Mirror PP Hybrid Michael Koster Tubes / Valves 43 13th May 2009 12:19 AM
Values for OTL totem pole (cathode followers) 00940 Tubes / Valves 2 10th November 2007 10:02 AM

New To Site? Need Help?

All times are GMT. The time now is 07:10 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