Diagnosing amplifier problem - current dependent?

Discussion in 'General Electronics Chat' started by Veracohr, Oct 31, 2015.

  1. Veracohr

    Thread Starter Distinguished Member

    Jan 3, 2011
    There's a stereo receiver I've looked at which the right channel intermittently cuts out. When I got it to my place and tested it I didn't find any problem, but as soon as it was back in its place it acted up again. I'm wondering if a transistor may exhibit problems only when passing a certain amount of current. When I tested it I was running it quietly but the person who owns it usually runs it louder. Could it be useful to get some power resistors to simulate a speaker so I can test it at a higher volume setting than I want to listen to for a long period of time?

    It's a Sansui 5000x, capable of 55 watts per channel into 8 ohms. If you want to look at the schematic it's here: http://akdatabase.org/AKview/albums/userpics/10004/Sansui 5000X Service Late.pdf

    The driver board is in the lower right corner, just above the power supply, labeled F-1040-1A. I'm pretty sure the problem is there because it doesn't depend on the source selected.
  2. dl324

    AAC Fanatic!

    Mar 30, 2015
    Could be current causing a temperature rise. You can check for thermal issues with a heat gun and freeze spray.