Question about JVC HR-S3912U S-VHS VCR
While watching TV the other day, my HR-S3901 display went to "AUT" and the signal was lost at the TV. When it does this, the unit locks up and no front panel or remote buttons have any effect. Having a VCR years ago that locked up, I unplugged it and re-plugged it in and the unit came back on. After about 30 minutes it did the same thing. However it is now stuck in this mode. Whenever the unit is plugged in, it blinks a channel 2 very quickly, then it goes into the AUT mode. Sometimes after about 10 minutes, the -:-- shows on the display. But in no case do any of the buttons do anything nor can I get any picture out of it. I tried the holding of the power button for 10 seconds trick with no success. Any ideas?
One possibility is that the power supply section isn't providing the correct voltages. If you have a little tech savvy, and a volt meter, check the output voltages. There should be a +5 volt line, +12 to +14 volt line, and perhaps a -40 (approx) volt which supplies the display. Early VCRs often had this latter voltage, but later ones not having much of a display might not. Anyway, check for these voltages- the +5 volt should be right on within .2 volts (4.8 - 5.2volts). If this voltage is off much more than this, problems are likely. Defective components would likely be the electrolytic capacitors in the power supply, most of which are used to filter those noted voltages. If by chance one or more caps. is defective, replacements are found at Digi-Key Corp. Their Panasonic FC capacitors are what I generally use for most of these replacements. Mouser Electronics will have suitable parts too. Beyond this problem, maybe an erratic mode switch, or other logic problem. The kind of problem you describe may be difficult to diagnose. If this is a late VCR (10 years old or less), most of these are of the disposable variety, unlike the old rigs which were built like tanks, comparatively speaking.
Posted on Jul 03, 2007
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