TV/VCR/Stereo Troubleshooting/Pioneer SX-J990/S/DF


I have a Pioneer receiver, the SX-J990/S/DF.
After a short in one of the speakers, when turned on, the system switches back to standby mode after a few seconds.
Tested it, had two main transistors of amplifier output in short (just of the channel where the short occurred), they have been removed. As they are only responsible for one channel of the amplifier, I tried to turn on the system, without success.
I saw a similar system (SX-J990/HL) had the same problem, but even reading the suggestions of this site, did not work.
Help me!
Sorry if has some grammar errors.

Just pulling the output transistors in the bad channel may not allow the power supply to light up correctly. For example the pre-driver circuit can 'see' through to the output load. So, if you still have speakers connected or the speaker switch in the wrong position it could cause the amp to malfunction.  To be safe, also pull the driver transistors that drive the outputs.  Check to make sure there are no shorts or bad links.

Secondly, the output shortage could have caused one of the electrolytic capacitors in the main power supply to quit.  If you know how to replace them you might do that as the electrolytics are famous to give up earlier than other electronic components.  And, they are not expensive to replace, usually.

Hope this helps.  

TV/VCR/Stereo Troubleshooting

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