Entertainment Center: TVs, Stereos, VCRs and DVDs - JVC 27
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04-28-01, 02:31 PM
Have a 1993 JVC 27" TV. I wrote you a while back because it made a crackling or static type noise when it first started. Followed your directions of taking the back off the tv and looking for loose or disconnected ground. Did not find anything but vaccumed and blew the dust off the insides. The sound problem continued (actually got worse, took longer and longer to clear up) and now what happens is, the TV won't turn on. It sounds like it tries to turn on and then you hear a click, like a circuit breaker or protective device kicked in. The problem sounds similar to the Goldstar problem listed recentlly. How can I check and determine if the power supply is bad and what does it look like. Would appreciate any advice. Thank you
Smokey
04-29-01, 03:33 PM
Good Afternoon, hkenyon:
Wished you had followed up sooner but that is the fortunes of war. Cleaning the interior was a good move on your part for the longevity of the electronics if nothing else. You didn't hurt a thing by doing it. Picture tubes are like giant dust magnets and their magnetic properties attract everything that is airborne.
The crackling of the set as it warms up could have been a bad ground and is the most common problem. The outside of the glass on the tube ionizes positive and a ground ring is provided on the tube to shunt the ionization to ground. Again, the first answer was based on commonality of problems.
This time, however, it would appear that what was happening is the high voltage regulator circuit had failed. The high voltage produces about 45,000 volts to the picture tube which is used to both light the screen and and focus the image. The high voltage power supply is capable of producing more than 45,000. As I recall, it can go as high as 56,000 volts. Therefore some form of regulation is required. Also, without regulation, the picture would go out of focus when you turn up the brightness.
I fear the high voltage regulator circuit failed in this unit and the voltage has been running at maximum potential.
You may have noticed the picture "bloom" or change proportions when was running. In the newer sets, there is (what we call) a fault circuit that will make the set lose horizontal stability when the regulator fails. It should have caused the picture to be unwatchable and encouraged you to shut off the set in frustration. They designed it to frustrate you to keep from burning up the set.
I now imagine the high voltage circuit has failed in the set and now a short circuit exists. To this end, the set will not turn itself on and a circuit breaker circuit will prevent this. Without one-on-one diagnosis, I cannot determine how the failure occurred or what components are involved. At this point, you need professional help to solve the problem. Time to call the shop.
Smokey ;)
Wished you had followed up sooner but that is the fortunes of war. Cleaning the interior was a good move on your part for the longevity of the electronics if nothing else. You didn't hurt a thing by doing it. Picture tubes are like giant dust magnets and their magnetic properties attract everything that is airborne.
The crackling of the set as it warms up could have been a bad ground and is the most common problem. The outside of the glass on the tube ionizes positive and a ground ring is provided on the tube to shunt the ionization to ground. Again, the first answer was based on commonality of problems.
This time, however, it would appear that what was happening is the high voltage regulator circuit had failed. The high voltage produces about 45,000 volts to the picture tube which is used to both light the screen and and focus the image. The high voltage power supply is capable of producing more than 45,000. As I recall, it can go as high as 56,000 volts. Therefore some form of regulation is required. Also, without regulation, the picture would go out of focus when you turn up the brightness.
I fear the high voltage regulator circuit failed in this unit and the voltage has been running at maximum potential.
You may have noticed the picture "bloom" or change proportions when was running. In the newer sets, there is (what we call) a fault circuit that will make the set lose horizontal stability when the regulator fails. It should have caused the picture to be unwatchable and encouraged you to shut off the set in frustration. They designed it to frustrate you to keep from burning up the set.
I now imagine the high voltage circuit has failed in the set and now a short circuit exists. To this end, the set will not turn itself on and a circuit breaker circuit will prevent this. Without one-on-one diagnosis, I cannot determine how the failure occurred or what components are involved. At this point, you need professional help to solve the problem. Time to call the shop.
Smokey ;)
05-02-01, 06:49 PM
Smokey,
Thanks for your help. I will get back with sooner the next time I post a problem. You gave me several things to try and check that could have been the problem and that I could fix. This information was very helpful. As you indicicated in your posts with the high labor costs it just doesn't seem smart to get the older TV's fixed. Not sure if that's a good thing or not. Thanks again, Herb
Thanks for your help. I will get back with sooner the next time I post a problem. You gave me several things to try and check that could have been the problem and that I could fix. This information was very helpful. As you indicicated in your posts with the high labor costs it just doesn't seem smart to get the older TV's fixed. Not sure if that's a good thing or not. Thanks again, Herb