Introduction

am an amateur astronomer, and needed a watch that was visible in the dark so I don't have to walk around in the dark carrying a big alarm clock. This watch is nice, but did not suit my needs. It is also very hard to figure out how to set the time, mainly because the manual is very badly written.

In spite of the terrible manual, I finally figured out how to set the time and created this page as a reminder. Hopefully it will help other owners as well. The first part of this document is a review. Part two is the Instructions.

Review of G-Shock GW-4000D-1A (Casio 5087)

G-Shock GW-4000D-1A with silicone strap attached

It's a watch, so really the only relevant questions are: does it look nice? Is it easy to read the time? and Is it accurate? The answers are: yes, yes, and only if you can figure out how to set it.

The other question is: are the extra features, which include a UTC display, alarms, battery-free operation, a stopwatch mode, and automatic wireless time setting, worth the extra cost? After using this watch for a year, I would have to say no. But would I buy it again? Heck, yeah.

Good points

1. If charged, the luminescent hands remain visible for most of the night. The entire length of the minute and hour hands, as well as the 3 numerals (6, 9, and 12) and the twelve white dashes around the outside, are luminescent, but the second hand is not. The numerals give off a slightly bluer phosphorescence than the hands.
   
   
2. Getting into and out of stopwatch mode takes only a couple of presses, and the buttons are easy to press. Too easy—my watch tends to go into stopwatch mode almost at random.
   
   
3. By default the small lower left dial points to UTC. This might be a great feature if that dial were not also covered up most of the time. The small dial in the upper left is a 24 hour dial, which is also usually covered up and is hard to read accurately. Effectively all it tells you is whether it's AM or PM.
   
   
4. It has a real second hand, unlike the “chronograph” watches, where the second hand is stuck at 12:00 except in stopwatch modes.
   
   
5. The time zone is easier to set than other G-Shocks, if you follow the instructions literally. On my other G-Shock, I had to set the time zone to Halifax, Nova Scotia, wait for it to sync with WWVB, then re-set it to New York before it would display the right time. The time zone codes around the outside are not for decoration. To set your time zone, you press the upper left button for 5 seconds. The second hand then acts like a Ouija board pointer, moving to Yes or No for a few seconds, then moves again to point to your time zone. Only after it stops moving can you change the time zone. Unlike a normal watch, there is no stem—only four pushbuttons. Casio should give it a wireless browser interface to make it easier.
   
   
6. The black part around the dial is not as rubbery as some other watches. The crystal is plain glass, but it's recessed, so if you bump the watch against something it won't scratch the object. However, the strap is metal, which means it will scratch things, and it makes a lot of noise if it touches anything.
   
   
7. It is water-resistant and shock-resistant, so I can wear it while digging post holes and then wash the dirt off it under a faucet. However, the crystal is ordinary glass and is easily scratched by the dirt. It might even be possible to take a bubble bath while wearing this watch, although I haven't tested that yet.
   
   
8. It is reasonably accurate. Over the past year it has usually been within ±1 second of the correct time; occasionally up to ten seconds off—except when it gets screwed up (which it often is) in which case it's off by several hours. I found myself wishing it had a Ctrl-Alt-Delete key.

Bad points

1. After one hour in the dark, the watch goes into a sleep state, regardless of the battery's charge, and parks the second hand at 12:00. You have to push a button or shine a light on it to start it ticking again. This is very inconvenient for us astronomers. It doesn't always work, either: sometimes the second hand remains at 12:00 and you have to press 'C' several times to get it started again.
   
   
2. The description on the Internet was incorrect: there is no “EL” display on this watch, nor is there an LED backlight. Only green phosphorescence. There is no “Flash Alert.” The stopwatch capacity is not 23:59:59, but 0:23:59.99. It's solar-powered, not battery-powered. The day of the month display is recessed, so it is in shadow most of the time, which makes it almost unreadable.
   
   
3. This is a really big watch. It is 16 mm thick, which makes it too big to wear with a long sleeved shirt. Anyway, long-sleeved shirts would cause it to go into sleep mode. It is also heavy: 135 grams (3/10 of a pound). This is 2½ times as heavy as a G-Shock AWG-M100 (55 grams). So I replaced the metal band with a silicone rubber strap for a GW-4000-1A (which is the same except for the strap and the color of the lettering) from a watchbands online vendor, which reduced the weight to 72 grams.
   
   
4. In Stopwatch mode, the main second hand makes one revolution per second, but only for the first 30 seconds. Then it stops. The stopwatch seconds and minutes are not displayed on the main dial, but on the small dial in the lower left. When you press Stop, you read minutes and seconds from the lower left dial, tenths of seconds from the main second hand, and hundredths from the small Day of the Week pointer on the right. Reading these dials correctly is not easy, especially when they are covered up by the main hands.
   
   It was so hard to read the elapsed time that I finally gave up on it, and only use it as a watch. It's much easier just to use a stopwatch app on a cell phone.
   
   
5. There is no way to turn off the radio, so if you live in Newfoundland, Hong Kong, or Hawaii, you can't use this watch because it will automatically get screwed up if it ever picks up a signal.
   
   
6. Unlike digital G-Shocks, there is no signal strength display for the receiver or for the charge state. According to the manual, it has three charge states: Normal, Low (second hand jumping two seconds at a time), and Really Low (none of the hands move at all and the settings are erased), which is a lot like “dead.”
   
   
7. This watch requires more light than my other G-Shock. I had to set up a special lamp and keep it charging every night. The manual says it takes 22 hours of full sunlight to fully charge it and 91 hours for indoor light to bring it from “dead” to “almost dead.” After a few minutes of bright light the hands move to the correct time and the day of the month display changes to show the correct date.
   
   
8. The one I have is unreliable. It will occasionally stop ticking and then jump thirty minutes ahead for no apparent reason. The buttons don't always activate when pushed. At seemingly random times it goes into 'Receive' mode, causing the second hand to be stuck on 'R' for several minutes. Sometimes all the dials (including the hour and minute hands) start moving around apparently at random, even though none of the buttons were pushed. It's not easy to get the watch out of this screwed-up mode. If you're bored a good way to pass the time is to stare at it to see if you can catch it spontaneously jumping to another time zone.
   
   These are what give the watch its character. After all, what fun is it if your watch is so dull it always tells the correct time? People need to loosen up about these things.
   
   
9. The manual is like a 73-page fortune cookie. A PDF version is on Casio's website.

After wearing the GW-4000D for a few weeks, I feel I am ready for something bigger. Next week I will strap a refrigerator to my wrist. If that works, I'm ready for something really big, like a Dodge Camaro.

How to set the time on a Casio G-Shock 5087 GW-4000D watch

There are 4 buttons:

 A     B
    o
 C     D

• A controls whether you are in setting mode or timekeeping mode.
• B makes the hands move counterclockwise.
• C cycles between the different modes.
• D makes the hands move clockwise.

What makes this watch tricky is that the buttons do different things depending on the mode, and there's no indication of which mode you're in. For example: to get back to timekeeping mode at any time, press C for 2 seconds, unless you're in time setting mode, in which case pressing C would cause you to screw up the calendar, and you have to press A instead. If you're in time-setting mode, pressing and holding D sets the time, but if you're in normal mode pressing and holding D re-sets the hand positions, which can make the watch unusable.

A symptom of this is when the date changes at noon or some other random time instead of midnight. For example, if the date changes at noon, it means the hand positions are messed up, and you have to correct them manually so the upper left dial points to 24. (Page E-61 in the manual says 12, which is wrong.)

Another symptom of this is when it keeps time accurately until it picks up a radio signal.

To put watch in manual radio receive mode

Press and hold A for 2 seconds, then release A.

The second hand will spin around and point to Yes (= it received a radio signal before), or No (= it did not receive radio signal). Then it will move to R (= Ready to receive). If there is a radio signal, it will automatically move to W (= Working). If the signal is too noisy it jumps back to R and tries again. After several attempts it gives up and returns to timekeeping mode. It is very rare for it to ever receive a signal, but it probably depends on how noisy your electric wiring is. One solution is to put it inside a tuned loop antenna tuned to 60 kHz, which will strengthen the radio signal.

To set the time

Press+hold A, passing through Manual Radio Set mode to get to Time Zone mode. You must continue to press A for at least 6–8 seconds. The second hand will move to Y or N, then to R, then to a time zone and stop. Don't release A until it points to a time zone. You are now in Time Zone/DST mode. From here, you press C to cycle to the next mode or A at any time to escape.

You can cycle through the time-setting modes by repeatedly pressing C. The modes are:

Time Zone/DST → Hour/minute → Year tens → Year ones → Month → Day → Hour/minute.

1. Press and hold A for 6–8 seconds ⇒ Time Zone/DST Mode.

Press B to toggle between DST and standard time.
Press D to move second hand until it points to the correct time zone.

After you set the time zone, the hour and minute hands will move. If they are now correct, press A for 2 seconds to get back to timekeeping mode. (Example: NYC = New York City = Eastern Time Zone.)

2. Press C ⇒ hour-minute mode.

You are now in hour/minute time-setting mode. The second hand should point straight up. Press D until time is correct AND upper left dial points to the correct 24-hour location (left=PM, right=AM). If the second hand starts moving, it means you are not really setting the time but changing the time zone, and the watch will jump to some other time when you are finished.

3. Press C ⇒ Year–tens mode.

Pressing C again puts you in Year – tens mode. You can only go in one direction. Press D to set 1=2010, 2=2020, etc. If you go past 9 it jumps to 12 (=2000). (Example: the second hand pointing at the 5-minute position means it is between 2010 to 2019.)

4. Press C⇒ Year–ones mode.

Pressing C again puts you in Year – ones mode. Change the year by pushing D. The second hand points to the last digit of the year. You can only go in one direction. If you go past 9 it jumps to 12 (2010, 2020, etc.)(Example: the second hand pointing to 4 (the 20-minute position) means it is 2014.)

5. Press C ⇒ Month mode.

Pressing C again puts you in Month mode. The second hand points to the month. Change it with D. The months are 1=January, 2=February, etc.

6. Press C ⇒ Date.

Pressing C again puts you Date mode. The second hand moves to 12 and stops. Press C or D until the small number in the date window is correct. It moves very slowly and centers itself when you release the button.

This is the last mode, but pressing C again does NOT return you to timekeeping mode. It puts you back in Hour/minute mode. Press A for 2 seconds to escape.

There is no way to set the day of the week. It is calculated automatically from the above. Whatever you do, don't press and hold D unless you're in time-setting mode. If you do, it puts you in the Hand Positions Correction mode. If you change the time without realizing you're in this mode, weird things will happen.

Alternatives

I also had a Casio 1330. It looks OK, it's inexpensive, and it's somewhat accurate (about 1 minute per month) and it only weighs 19.03 grams. But it's junk. The first time I used it the knob fell out. This made it a lot harder to set the time.

G Shock AWG-M100B (Casio 5230)

Here's how to set DST in a Casio 5230 (G Shock AWG-M100B). First make sure the watch is not upside-down. Then, to set Daylight Savings time, press A for two seconds. Wait for the hands to move so that the dials become visible. Press C to enter DST setting mode. It will say "On" or "Off". Then press B to toggle it on or off, or else press D to cycle between on, off, and auto. (Auto is useless because it's such a pain setting the date.) Then press A to get back to timekeeping mode.

Problems

1. After you set the time manually, the watch will operate normally for a while, then the second hand jumps to R. This appears to mean it has decided to listen for a radio signal, and has picked one up. The minute hand will move to the correct time and it will start up again.

2. If second hand begins spinning around, it means one of three things:
(a). You somehow entered stopwatch mode. Press C for 2 seconds to return to normal mode.
(b). Charge is very low. Expose it to light.
(c). It is broken.

3. Second hand jumping two seconds at a time means the charge is very low. Expose it to light.

4. If it spontaneously goes into Stopwatch mode (as mine does at random times), press C for two seconds until it beeps. Symptoms: second hand at 12:00, exposing watch to bright light has no effect, and stopwatch dial in lower left is rotating.

5. If it never synchronizes the time with WWVB, it usually means your time zone is set incorrectly. If your time zone is correct, you might need a tuned loop antenna tuned to 60 kHz (for users in the USA). However, at these low frequencies interference is a bigger factor than signal strength. Usually leaving the watch outside overnight as far from electric lines as possible (but also away from animals) is sufficient.

The WWVB signal is easier to pick up at night and in locations far away from any computers, LED lights, power transformers, and electric appliances. This low frequency radio wave travels exclusively as a ground wave, which means elevating the watch to a high elevation won't be of much benefit. The low frequency also minimizes differences in propagation delay that occur at higher frequencies that bounce off the ionosphere. This means the delay is easy to calculate. The signal has a narrow bandwidth and is very slow, about 1 bit per second, so it takes a whole minute to send a complete time code. See here for signal coverage maps from NIST and more tips.

That's what makes this watch so great. When other watches give the correct time, it's routine. When this one does it, it's like a miracle from God. And what could be better than carrying a miracle around on your wrist?

Nov 02 2014 8:30 pm 2:13 am 4:00 pm 9:30 pm; updated Nov 21 Nov 18 Nov 20 Nov 19