This Zenith DVD2381 has worked for years, except for a spell a few years ago when the tray would shudder but not quite open and close. I managed to free it up.
So tonight, when there was nothing on TV, my wife told me that when she had tried to play a DVD on Tuesday, it didn't work. She tried to turn it off, but the light in the power button stayed on. Nothing appears on the display: no "Hello," no "No disc," no nothing.
We tried unplugging it and plugging it in again, but that did not help.
The thing still looks pristine inside, so I hate to junk it without giving repair a shot.
Does this sound like a simple problem to fix?
How do laser safety interlocks work on those old DVD players? If the lid were off, would that stop all functionality? My SWAG is that this is not working.
That Acer LCD monitor I brought home sort of worked, except it kept resetting to the point where it was showing the logo on the screen. So the power supply was nominally good. I changed the larger value electrolytics in the power supply, none of them looked bad. And it's worked fine since.
A little bit of information is worse than a lot.
There were instances of "bad caps" but electrolytics by nature can dry out. It's about how they are used, and the heat they see.
In the tube days, most equipment had only a handful of electrolytics, in the power supply and to bypass the cathode resistor(s) in the audio amplifier chain. You could usually easily tell there was a bad electrolytic, you'd hear hum in the speaker (because the power supply filter capacitor went bad), or maybe lesser audio output.
Transistorized gear brought a lot more electrolytics, since tubes were high voltage low current, and transistors were love voltage high current. They needed electrolytics because the lower impedances meant a need for larger valuce capacitors, and the only way to get that in a small package was electrolytic capacitors.
And take transisfor radios from 40 or 50 years ago, and the electrolytics generally need replacing because they are now old.
But the real change was when switching supplies came along. Power supply capacitors before that only had to keep out 60 or 120Hz, pretty low frequencies. Switching supplies got by with lower value electrolytics, since they operated at a higher frequency, tens of KHz, but that meant the electrolytics had to work harder. And that's why they are now suspect when something with a switching supply goes bad. They are more likely to go bad than a diode or other component.
In the old days you would never see 120 deg C rated caps, even with all those glowing valves the caps did not get that hot. Combined with smaller physical size for the same rating. Has QC of elecrolyte and materials really got that good to allow for half size caps , compared to sizws before?
One not-uncommon failure mode in such devices, is bad electrolytic capacitors. They may go "high ESR" and fail to filter the power supply voltages properly, or they may swell and leak (failing to filter, and possibly damaging the PC board traces).
A decent capacitor ESR tester (which is different than a capacitance meter) can often identify such caps.
"Re-capping" the device requires identifying the failed caps (or just identifying "all the usual suspects"), removing, and replacing. If PC board traces have been damaged by electrolyte leakage, it would be necessary to rebuild them or bridge over the damaged areas.
It's definitely possible to do. It often isn't done commercially for lower-value products due to the cost of labor. When you can buy a DVD player for under $100, spending an hour of technician labor at $100 isn't a great bargain.
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