Timex Caliber G161C

The Timex G161C is circuit board movement found in a vintage Timex Marathon stopwatch.

The back of the watch has the number T5G811, but the official user manual references W-213 and 157-095000 NA.

Functions:

• Main time with hours, minutes, seconds, month, day of the week, and date
• Second time zone also with it’s own month/day/date.
• 24 hour chronograph stopwatch
• 50 laps memory with recall for date, best lap, and average lap
• 10 seconds auto start chronograph feature
• Speed calculator
• 24 hour countdown timer which can can down or up and repeat
• Pacer feature
• Seven weekly alarms
• Daily Alarm
• Hourly chime (can be turned off)
• INDIGLO night-light with NIGHT-MODE feature

Battery Life:

According to Timex, the battery in the Marathon stopwatch should last up to 2 years, but this depends on the use of the alarm and INDIGLO light functionality. The more you use the alarm chime and the backlight, the faster the batteries will need replaced.

How to Change the Batteries:

The Timex Marathon stopwatch is powered by two CR3032 batteries. There are 6 screws to get access to the inside to change the batteries out. The three smaller screws towards the bottom of the watch are for the lanyard.

Once inside, there is a cover over the batteries with two white stickers, one with the following text:

“AFTER BATTERY INSERTION – SHORT RESET PADS / CHINA / 189” -See below for more info about this

The two white stickers are attached to a metal cover/cell strap that holds the batteries in place. There is a screw on each side, holding the strap down and locking the batteries in place.

“Loosen (do not remove) screws holding metal strips over batteries and remove batteries.”-User guide

As quoted above, Timex states not to remove this cover, but Caliber Corner included an image below to show what it looks like and how the batteries are positioned. Just loosening the two screws should allow you enough room to slide the old batteries out and insert the new cells.

Keep in mind that the positive side of the battery goes up.

And below is a view of the terminals when the cover and batteries are removed:

Short Reset Pads:

After the new batteries are inserted into the metal clip, the watch may not work still. Even if it does start running, after a battery change you should do an AC reset to clear the system.

The left sticker with the Short Reset Pads message has an arrow pointing up. Above that, about halfway up, there is text on the circuit board: RESET with two metal pads to the right. Touch or tweezers, or another metal object to these pads to do the reset.

Immediately following the reset, the screen will momentarily blackout with all of the icons visible, but do not be alarmed as this is only the reset display and should go back to normal within seconds.

Beep Speaker:

The hourly chime and alarm sounds are made possible thanks to a piezoelectric speaker (aka piezo buzzer) attached to the caseback of the watch.

There are two springs on the circuit board that make contact with the piezo. If the sound isn’t working, check that the springs can reach the speaker.

Other Troubleshooting:

The official user manual has a section about activating the watch. It’s unlikely that this will apply to anyone who changed the batteries, but there is a power-down feature on the watch which may need activated if it is a new old stock device.

“Unit is shipped in “OFF” mode to preserve battery life. To activate unit, press and hold all five buttons simultaneously until STOP indicator disappears, about 4 seconds. When buttons are released, unit is ready for use.”

It is still unconfirmed how to get the watch into OFF mode, but possibly by reversing the step above.

Additional Resources:

• Official user manual (pdf)