Hey folks, first time poster here. I have a Sharp CD-DD4500. Its well cared for and somewhere about 5 years old. Well suddenly, the LCD display has crapped out. I get nothing but an almost imperceptible glow. It makes it darned hard to tell what I'm doing with the stereo. It is housed in a entertainment center cabinet with a glass door. I do notice that it gets rather warm in there, and I've plans to install a vent fan. Could this heat have had something to do with the problem. I imagine simply removing the heat won't fix it, so...any suggestions?
Is it really an LCD, or is it a VFD ? LCDs are either back or side illuminated, usually by minature incandescent bulbs, but sometimes by LEDs. It's very common for these to fail.
VFDs, on the other hand produce light, and are usually a green/ blue colour, although they can be any colour. To produce light, they need a heater supply - typically 1.5 to 3v AC, and a negative supply of -25 to -32v. This supply often goes low. It is usually derived straight from the mains transformer via a voltage multiplier, which employs electrolytic capacitors, which work very hard, having large AC across them all the time. They dry out and go low value, the negative voltage drops, and your display fades away. Sometimes, the heater is also fed via a capacitor, and same thing happens. Easy place to check the negative voltage, is from chassis to either of the display heater pins ( these are a pair at either end of the main pin row of the display panel, and are separated from the rest of the pins by an extra pin position ). The negative voltage can be measured here, because the heater is floated on it, to reduce internal voltage differential between display elements.
Some Sharp CD players from a few years ago, also used an LCD which was backlit by a piece of electro-luminescent material. This needs a couple hundred volts to light it up, and they used to have a little inverter on a sub board to generate this. When the inverter went faulty, the display went very dim. I don't think Sharp have used this for a while now, but just in case ...
NUMAtrekkie: The symptom that you described could be easy and inexpensive to repair or it could be much more involved and expensive to fix. In order for you to make an INTELLIGENT repair decision you really need to get a repair cost estimate. I suggest that you TAKE it to a service shop so a tech can open it up and actually make some tests and do some technical troubleshooting.... ONLY THEN can you get the facts about what is wrong and what it will cost to fix..... otherwise we are just guessing here. electricitym
ElectronDepot website is not affiliated with any of the manufacturers or service providers discussed here.
All logos and trade names are the property of their respective owners.