This morning I tried to turn my RCA TV (model 24R411T) on and nothing happened. I tried plugging it into a different outlet, still nothing. I tried leaving it unplugged about 10 minutes and trying again,...
Power surges or nearby lightning strikes can destroy electronic equipment. However, most of the time, damage is minimal or at least easily repaired. With a direct hit, you may not recognize what is left of it!
Ideally, electronic equipment should be unplugged (both AC line and phone line!) during electrical storms if possible. Modern TVs, VCRs, microwave ovens, and even stereo equipment is particularly susceptible to lightning and surge damage because some parts of the circuitry are always alive and therefore have a connection to the AC line. Telephones, modems, and faxes are directly connected to the phone lines. Better designs include filtering and surge suppression components built in. With a near-miss, the only thing that may happen is for the internal fuse to blow or for the microcontroller to go bonkers and just require power cycling. There is no possible protection against a direct strike. However, devices with power switches that totally break the line connection are more robust since it takes much more voltage to jump the gap in the switch than to fry electronic parts. Monitors and TVs may also have their CRTs magnetized due to the electromagnetic fields associated with a lightning strike - similar but on a smaller scale to the EMP of a nuclear detonation.
Was the TV operating or on standby at the time? If it was switched off using an actual power switch (not a logic pushbutton or the remote control), then either a component in front of the switch has blown, the surge was enough to jump the gap between the switch contacts, or it was just a coincidence (yeh, right).
If the TV was operating or on standby or has no actual power switch, then a number of parts could be fried.
TVs usually have their own internal surge protection devices like MOVs (Metal Oxide Varistors) after the fuse. So it is possible that all that is wrong is that the line fuse has blown. Remove the cover (unplug it first!) and start at the line cord. If you find a blown fuse, remove it and measure across the in-board side of fuse holder and the other (should be the neutral) side of the line. The ohmmeter reading should be fairly high - well certainly not less than 100 ohms - in at least one direction. You may need to unplug the degaussing coil to get a reasonable reading as its resistance may be 25 or 30 ohms. If the reading is really low, there are other problems. If the resistance checks out, replace the fuse and try powering the TV. There will be 3 possibilities:
It will work fine, problem solved.
It will immediately blow the fuse. This means there is at least one component shorted - possibilities include an MOV, line rectifiers, main filter cap, regulator transistor, horizontal output transistor, etc. You will need to check with your ohmmeter for shorted semiconductors. Remove any that are suspect and see of the fuse now survives (use the series light bulb to cut your losses - see the section.
It will not work properly or appear dead. This could mean there are open fusable resistors other defective parts in the power supply or elsewhere. In this case further testing will be required and at some point you may need the schematic.
Jun 14, 2010 |
RCA 27R411T 27" TV