Sansui AU-4900 problem - diyAudio
Go Back   Home > Forums > Amplifiers > Solid State

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 29th June 2015, 02:56 PM   #1
diyAudio Member
Join Date: Jun 2015
Default Sansui AU-4900 problem

Hi everyone.
I have a Sansui AU-4900 that I am having trouble with. Well... kind of..

See, outside the transformer there are 3 fuses. The one at the bottom (125V 6A) blows immediately every time. But the amp still seems to work great. All features appear to be working. I even had a microphone plugged in to try.

I have the schematic and circled where the fuse is. Does anybody have any ideas what the fuse is for?

Thanks for any help!
Attached Images
File Type: jpg Capture.JPG (119.1 KB, 44 views)
File Type: jpg FullSizeRender (1).jpg (620.3 KB, 44 views)
File Type: jpg FullSizeRender (2).jpg (603.1 KB, 39 views)
  Reply With Quote
Old 29th June 2015, 04:39 PM   #2
diyAudio Member
JonSnell Electronic's Avatar
Join Date: Dec 2012
Location: The Jurassic Coast, England. GB
Send a message via Skype™ to JonSnell Electronic
Hard to tell where your circle is. Is it one of the yellow high lights? There are no fuses of that value listed in the schematic.
Support for Flying Mole Class D, Allen & Heath, Valve amps, older designs & 2CVs.
  Reply With Quote
Old 29th June 2015, 04:57 PM   #3
diyAudio Member
Join Date: Jun 2015
Hi.. sorry, the fuse is where I highlighted it and underlined in red. the other two highlights are where the other two fuses are..
Yes the fuses are not shown on the schematic. And other amps of this model online just have and empty area where these fuses are.

I'm wondering if that fuse is used when this is plugged into another countries outlet of 240V. It would be drawing less amperage at a higher voltage? Just a thought
  Reply With Quote
Old 29th June 2015, 05:03 PM   #4
diyAudio Member
Join Date: Jun 2015
I guess I say "other countries" and I should say non- Canadian. haha/.. We have 120 volts here. The amps I see online of this model seem to be from Australia and GB. They don't have the fuse. So perhaps that is the difference.
  Reply With Quote
Old 30th June 2015, 06:25 AM   #5
roger2 is offline roger2  United States
diyAudio Member
Join Date: Mar 2004
Location: indiana
You may get more replies if you increase the size of your schematic. Or enlarge the relevant section and post again. I am not able to read the schematic in your OP
  Reply With Quote
Old 30th June 2015, 06:34 AM   #6
diyAudio Member
picowallspeaker's Avatar
Join Date: Apr 2007
I blew twice the power transistors of my marantz 1122DC because the fuse for 110 V wasn't changed to 220V ( halved )
But...what a sound

BTW now I have a sansui au 5500...but this 4900 appeals me more
  Reply With Quote
Old 30th June 2015, 06:47 AM   #7
diyAudio Member
Join Date: Jun 2015
I think I found the issue. A shorted diode.
  Reply With Quote
Old 30th June 2015, 07:51 AM   #8
diyAudio Member
Join Date: Sep 2009
Location: Timisoara
Yes, your fuse connected one of the two secondaries to the rectifier bridge.
Your amp was working without the fuse, but with half rectification.
Change the rectifier and the fuse and you're good to go
  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
Sansui AU 4900 problem chiunana Solid State 44 6th December 2014 09:43 AM
Help with Sansui AU-4400 scid714 Solid State 4 4th January 2014 03:46 PM
WTB: Sansui AU-70 or AU-111 for restore (doesn't have to be working) hatrack71 Swap Meet 0 14th August 2012 12:33 PM
sansui au-6900 newf Solid State 8 25th May 2010 02:08 AM
Sansui Au-517&au-717 ManUtd Solid State 4 29th March 2004 02:13 AM

New To Site? Need Help?

All times are GMT. The time now is 07:50 PM.

vBulletin Optimisation provided by vB Optimise (Pro) - vBulletin Mods & Addons Copyright © 2015 DragonByte Technologies Ltd.
Copyright 1999-2015 diyAudio

Content Relevant URLs by vBSEO 3.3.2