Zenith DVD Combo Home Stereo System

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I have a Zenith DVD/Stereo Combo home theatre system. I bought it
about 3 years ago. It worked very well until recently. It made a pop
noise while operating and the unit powered off. Now if you try and
power up the reciever, it will emit a high pitch frequency for about
half second and completely shut down. If you try and power it up
again, nothing happens but if you unplug the unit, wait 2-3 minutes
and plug it back in, the unit will enter standby mode and the red
indicator light will be on. Then if you hit the power button to turn
the unit into active mode it will emit the high freq. noise again and
shut off. Any advice you can give me on what the problem could be and
how to fix it would be greatly appreciated.

Thanks,
Craig

 

[Arfa Daily]

I have a Zenith DVD/Stereo Combo home theatre system. I bought it
about 3 years ago. It worked very well until recently. It made a pop
noise while operating and the unit powered off. Now if you try and
power up the reciever, it will emit a high pitch frequency for about
half second and completely shut down. If you try and power it up
again, nothing happens but if you unplug the unit, wait 2-3 minutes
and plug it back in, the unit will enter standby mode and the red
indicator light will be on. Then if you hit the power button to turn
the unit into active mode it will emit the high freq. noise again and
shut off. Any advice you can give me on what the problem could be and
how to fix it would be greatly appreciated.

Thanks,
Craig

Almost certainly caps in the power supply. Look for any with domed tops.
They are very common as failures on the secondary side. If none look
obviously bad, it will be necessary to check them with an ESR meter. Another
possibility, if you heard a pop initially, is that one of the output ICs has
failed, and is now loading up the power supply, causing it to go into
shutdown. Often, the output IC's are on a separate board, with its own 3 or
4 pin power connector coming straight from the power supply. You can usually
just unplug this, which will isolate any output IC problems from the supply
board. If you are not used to working with switch mode power supplies, be
very careful as they are not isolated from the line voltage, and are thus
potentially very dangerous. Also, the main primary side resevoir cap can
stay charged to a very high voltage on a non-functioning supply, for several
hours - or even days in some cases.

Arfa