Won't Power up fuse is not blown
Since the fuse doesn't blow now (you did replace it with one of the same ratings, right?), you need to check for:
Other blown fuses - occasionally there are more than one in a DVD.
Replace with one of exactly the same ratings.
Open fusable resistors. These sometimes blow at the same time or in place of the fuses. They are usually low values like 2 ohms and are in big rectangular ceramic power resistor cases or smaller blue or gray colored cylindrical power resistors. They are supposed to protect expensive parts like the HOT but often blow at the same time.
If any of these are bad, they will need to be replaced with flameproof resistors of the same ratings (though you can substitute an ordinary resistor for testing purposes). Before applying power, check: Rectifier diodes, horizontal output transistor, regulator pass or chopper transistor (if present), and main filter capacitor for shorts.
An initial test with an ohmmeter can be done while in-circuit. The resistance across each diode and the collector to emitter of the transistors should be relatively high - a few hundred ohms at lest - in at least one direction (in-circuit). If there is a question, unsolder one side of each diode and check - should be in the Megaohms or higher in one direction. Removed from the circuit, the collector-emitter resistance should be very high in one direction at least. Depending on the type, the base-emitter resistance may be high in one direction or around 50 ohms. If any reading on a semiconductor device is under 10 ohms - then the device most likely bad. The filter capacitor should eventually measure high in one direction (it will take a while to charge from your ohmmeter). It could still be failing at full voltage, however.
If you find one bad part, still check everything else as more than one part may fail and just replacing one may cause it to fail again.
May 21, 2010 |
RCA DRC8320 DVD Recorder/VCR