El backlight "A" key only changes f to c. Screen goes blank and no light?

No, the display shows all the time. The backlight allows you to see the display at night. The manual states

1. Press 'D' or 'EL' in any mode to illuminate the watch face. The backlight will remain lit for 3 seconds. NOTE: EXCESSIVE USE OF LIGHT WILL SHORTEN BATTERY LIFE.

So basically, they are telling you to only use the backlight feature WHEN you REALLY need it!

Orbit Chrono 31 - Armitron

www.armitron.com > products > mens-chronograph-black...
Orbit Chrono 31 · 31mm Black Resin Case · Black Resin Strap with Buckle Closure · Features time, seconds, day/date, chronograph with lap time, alarm, countdown ..

..

1. In any mode, press LIGHT key to activate EL Backlight;
2. In any mode, press MODE key to switch modes, such as alarm, day and date etc.;
3. In any mode, hold RESET into setting mode, and press START to adjust the value.

http://www.fixya.com/support/t7937662-just_got_lasika

Hold down the mode twice and then use the start button to edit the time.

Clear sign for a battery replacement as soon as possible.

The Casio Forester FT500WVB watch has an EL (Electroluminescent) backlight and requires one silver oxide button battery. The SR621W battery (also known as type 363) is recommended by the instruction manual for the watch. Note the suffix "W" means this battery is a high drain type which is suitable for powering a watch mechanism and the EL light as well for 2 to 3 years, depending on use of the light. "SW" suffix batteries are low drain and are intended only to power a watch mechanism, and not a light. Note also the "SR" prefix indicates the battery is silver oxide and not lithium. The SR type batteries do not use mercury and are therefore safer to dispose of when they are discharged. I have found the type SR626W (also known as type 377) battery is also suitable for the FT500WVB watch and it has more stored power and should therefore last longer.

Last, the Casio Forrester FT500WC looks exactly like the FT500WVB, but it is a different watch internally. The FT500WC has an LED light and requires two batteries- the SR920SW low drain silver oxide battery which powers the watch mechanism and the CR1616 lithium battery which powers the LED. The LED is brighter than an EL light and stays on longer than the EL light when activated. But the LED has a bright dot light source that some might find annoying.

you have to change the battery of your watch. the battery is low powered that why it does not light up and it goes blank. i hope i had been helped you.

I would advise to check out if there are two separate batteries. It is quite common for watch manufacturers to use one battery for backlight and another one for watch movement itself.

You can change the backlight on a casio wristwatch by holding the Light button, but only if it has an LED light in the side of the screen such as yours does. There is Light Blue, Red, Pink, Blue, Green LEDs in the side of the screen and you can change between them. There is also an option that flashes between all the LEDs when you press the button.

The "eye" icon appears when you have your backlight set to auto. that means when you move your wrist to look at your watch the light comes on automatically. I have found this to be a huge drain on the life of the battery. to turn it off hold down the light button (the grey button on the front with the red "g" on it) untill you hear it beep.

As for the watch dieing when the alarm goes off that is a good indication that you need a new battery.

Change the battery. This happened with mine along with the battery needing charging more frequently. In my opinion, Casio's assertions that you won't need to change the battery is pretty much of a joke. My jewler concurred.

After changing the battery I can now press the light switch button and the watch works normally.

Tony

I put a new CR2025 battery in my T5e671 Timex and it solved the problem.
The screen no longer goes blank at any time.
PS:Timex manual says "remove battery strap" to replace the battery.
But it doesn't say HOW.-& I couldn't google an answer to that.
Here is how:
The metal strap goes across the middle of the battery and then goes over the edge of it on both sides.
At both edges the metal strap goes over a nylon tab.
One of those nylon tabs is notched, if you put the end of a paperclip in the notch, you can release the metal strap edge that runs under it.