Seiko Caliber 7x52a

Seiko Caliber 7X52

Seiko Caliber 7x52

BrandSeiko
Caliber Number7X52, 7X52A
Movement TypeQuartz, Solar Powered
Jewels10
Crystal Oscillator Frequency
32,768 Hz (cycles per second)
Driving System
Step motor
Capacitor
CLB2016 (3.7V)
FunctionsAutomatic GPS time setting, date, dual-time, in-flight mode
Country of ManufactureJapan
Known ModelsSAST005, SAST007, SAST015

The Seiko caliber 7x52A is found in the first generation of Astron watches. It is a 10 jewels, solar-powered quartz movement. Made in Japan.

Detailed Features:

  • GPS controlled time and time zone adjustment
  • Perpetual calendar correct to February 2100
  • Signal reception result indication
  • World time function (39 Time Zones)
  • Daylight Saving Time function
  • Power save function

Accuracy:

Seiko claim the accuracy of the 7X52 in normal conditions is +/- 15 seconds per month.

Charging Time:

The Seiko caliber 7X52 requires more energy than other solar watches because of the GPS signal reception. The charging time depends on the light source and how how much light is emitted, measured in LUX. The higher the LUX the faster the charge. For example, charging in the sunlight will be faster than using a standard light bulb.

  • 3,000 LUX florescent bulb takes ~530 hours to fully charge
  • Daylight on a cloudy day takes ~135 hours to fully charge
  • Sunlight on a sunny day takes ~65 hours to fully charge

Power Reserve:

It literally takes days to charge the Astron, however, when fully charged the caliber 7X52A has a power reserve of about 6 months.

Note: when charging your watch in the sunlight, make sure that the temperature is not too hot or it can damage the dial, solar cell, or other parts of the watch. Always keep the watch temp below 60 C.

Can you wear it while charging?

You can wear your watch while it has low power or while it is charging, however, it may slow down the charging time if your watch is under your sleeve or not in direct light.

Can you overcharge it?

The Seiko caliber 7X52 has an overcharge prevention function to make sure your watch will not be over charged.

Low Power Indicator:

The Seiko 7X52 has several series of low power warnings:

  • Second hand ticks every 2 seconds: The watch will still tell the time, but the GPS automatic time setting will not work until it is charged.
  • Second hand ticks every 5 seconds: The watch will stop telling the time and the GPS will not function until it is charged.

From Seiko:

“While the watch is being charged, the second hand moves at “ 5-second Intervals.” During the “5-second Interval Movement,” neither the buttons nor the crown can be operated.”

2 Power Save functions:

The second hand has stopped at the 15 seconds mark: Power Save 1 function has been activated. The time display will stop and the time cannot be set until the watch is charged. This Power Save setting can be initiated with as little as 72 hours without a sufficient light source.

The second hand is pointing to the 45 seconds mark: Power Save 2 has been activated. The time will stop and the date will display 1. The time cannot be set until the watch is charged. This Power Save setting is initiated when the watch is in storage or without a light source for a long period of time.

Rechargeable Capacitor:

The capacitor (secondary battery) that is installed from the factory is a 3.7V rechargeable cell. The number is CLB2016. Also stamped on the cell is 12 and 63M. This oem part is manufactured by Maxwell in Japan and appears to only be available to manufacturers and not to the consumer market. Even if you are able to locate a CLB2016 cell (from here for example), it likely won’t have the correct tabs to hold it in the movement.

If you take your watch to a watchmaker or jewelry store for battery replacement, they will most likely tell you the watch it not repairable or the cell is not made anymore. The CLB2016 is still made, but not sold by the standard watch parts suppliers.

If your 7X52 powered Astron is not functioning due to the CLB2016 not holding power, you will want to plan on sending your watch to Seiko for service. At the time of this post, the cost for Seiko to service a 7X52 watch is $332.00 USD.

Do not try to fit a standard battery!

Seiko Caliber 7x52 Clb2016 Capacitor

Replacing the Capacitor:

Watch capacitors/rechargeable batteries do not last forever. Sometimes they will need changed, or sometimes you pull the battery to get a photo of the movement. According to the notice on the battery cover, when replacing the cell you must “short AC and + of the battery”.

Seiko Caliber 7x52a Battery

From Seiko:

“The battery used in this watch is a special secondary battery, which is different from ordinary batteries. Unlike an ordinary silver oxide battery, the secondary battery does not require periodic replacement. The capacity or charging efficiency may gradually lower due to long-term use or operating environment. In addition, long-term use may shorten the charge duration due to wear, contamination, lubricant deterioration of mechanical parts, etc. Request repair when the performance lowers.”

Examples of watches with this movement:

Seiko Astron Sast007 7x52Seiko Astron Sse060 7x52Seiko Astron Sast009 7x52

Additional Resources:

 


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Ted
Ted
7 years ago

Hi guys, I’m confused by this one. Is it quartz or solar powered? Love the site by the way!

Ken
Ken
5 years ago

Where can I find a battery for this model?

Ken
Ken
5 years ago
Reply to  Caliber Corner

Yes , I’ve tried leaving it on the window ledge but it does fully charge. From what I found,the battery can not be bought, you have to send it in for have it changed. Not very practical. Thanks for your help.

PD Mathur
PD Mathur
2 years ago
Reply to  Ken

I was able to get an LIR2016 to work in place of the original battery (able to get from Amazon for $7/2 pcs). I have posted instructions on watchuseek.com. Still on full charge after 5 days. I am waiting to see how long it takes to discharge to normal and recharge again. Will post results.

Gabriel Lantos
Gabriel Lantos
2 years ago
Reply to  PD Mathur

Gabriel

Gabriel Lantos
Gabriel Lantos
2 years ago
Reply to  Gabriel Lantos

Hello Mr. PD Mathur with I could not find your instruction posted on watchuseek.com to change the batteries(capacitor) on the SEIKO ASTRON GPS SOLAR watch. Would you kindly provide me with your instruction how do it!
Thank you in advance
Regards

PD Mathur
PD Mathur
2 years ago
Reply to  Gabriel Lantos

This website appears to be buggy. I posted a response; it showed posted and now it is gone.

PD Mathur
PD Mathur
2 years ago
Reply to  PD Mathur

Looks like links are not allowed here. I used a pair of forceps to peel off stickers gently, a pair of scissors taped open to unscrew the back (open with firm pressure so you don’t slip and scratch the back), and the smallest flat head screw driver from a set of jeweler’s screw drivers to open the two tiny screws inside the watch and to put the flat head between the clip and the battery… Read more »

trackback
Seiko Caliber 8B43 Watch Movement | CaliberCorner.com
3 years ago

[…] The Seiko Astron models feature similar functionality, check out the caliber 7X52 here. […]

Benny D
Benny D
2 years ago

I have an Astron that I bought when it first came out but it has been in my drawer for the past 8 months and lost all power. It would not move at all until I put it on the window for a week. Does anyone know of a faster way to charge these?

Benjamin
Benjamin
2 years ago
Reply to  Benny D

Sun during day, led lamp at night

Graham
Graham
2 years ago
Reply to  Benjamin

The LED lamp I used barely has an effect. Do you know if some LED work better than others?

Ben
Ben
2 years ago
Reply to  Graham

I used the led lamp of my aquarium. It’s perfect because it’s powerful (1000lx measured with free apps on my phone) , cold and flat so I could place it half an inch from the watch 24/7 without the watch getting even warm. Took 2 weeks from E to F

Ben
Ben
2 years ago
Reply to  Ben

Edit, measurement was 10,000 lx

PD Mathur
PD Mathur
2 years ago
Reply to  Ben

I had the same issue and Google searches returned nothing useful. As of tonight, here is what I have done. – Bought a couple of LIR2016 rechargeable batteries from Amazon. https://www.amazon.com/gp/product/B078Z9M3SQ/ref=ppx_yo_dt_b_asin_title_o00_s00?ie=UTF8&psc=1 – Opened the watch. Using a small flat head screw driver, removed the plate that holds the battery down. Gently peeled off the white sticker (need later). – Using the head of the small screw driver and applying counter pressure from the other side… Read more »

PDMathur
PDMathur
1 year ago
Reply to  PD Mathur

Update: It took a few more days than I thought for the needle to return to the middle. Happened on July 16 after I initiated the full GPS synch. I have not taken any special measures to charge it back. Will leave by a window for a few days and see what happens.

Eddie M.
Eddie M.
1 year ago
Reply to  PDMathur

These Astrons take about a month to properly charge. It’s way too long imho, but it will last forever on a full charge. I just wish they would make the capacitor available for the general public.

PD Matbur
PD Matbur
1 year ago
Reply to  PDMathur

Some sad news about my experiment folks: the replacement battery does not appear to be charging unless the watch ia exposed to very bright light. At that level it is taking a lot longer than the manual suggests, but it does eventually charge from E to middle with 14 days under a lamp (like the old battery did). I believe this is indicating a solar cell or chargin circuit issue (as another poster on another… Read more »

Gerry
Gerry
5 months ago

I own a astron sast003 gps watch. It is seven years old and no longer takes a full charge. It would not stay at half charge. So I took the battery out, put it on 4.5volt charger for an hour until it got hot. afterwards when reinstalled it read full charge for several days. Now it always stays at half charge. This proves I need a new battery. However nobody will sell me a new… Read more »

Fred Dreger
Fred Dreger
5 months ago
Reply to  Gerry

Mine was doing the same thing. They said they had to order the rechargeable battery. $60.00. Keeping my fingers crossed that it works after I get it back.

Gerry
Gerry
5 months ago
Reply to  Fred Dreger

I would like to know where to order the battery. Thanks for the info.

Fred Dreger
Fred Dreger
5 months ago
Reply to  Gerry

The watch is at the jewelers now. When I pick it up I’ll ask them. They acted like it was no big deal to get it working properly. I bought it in 2013 and then bought another one in 2016. The 2013 sat closed up in its box for 3 years. Like you, when I tried to charge it, it only went to half, then went back to E overnight. Left it out on sunny… Read more »

Daniel
Daniel
5 months ago
Reply to  Fred Dreger

Interesting conversation. Indeed, own a 7×52 seiko since 2014, and it exhibits the same behavior. Would be interested for the outcome.

Fred Dreger
Fred Dreger
3 months ago
Reply to  Daniel

Well, bad news. 2 watchmakers are telling me the watch is toast. The battery is shot and no longer made. I now have an $1,800 watch that is only 7.5 years old and completely useless. To say that I’m totally disgusted with Seiko would be an understatement. I’ve been wearing Seiko’s all my life because I perceived them as being excellent quality. Boy was I wrong.

Fred Dreger
Fred Dreger
3 months ago
Reply to  Caliber Corner

I appreciate the heads up, I’ll look into it. Thanks!

Bob Parker
Bob Parker
3 months ago

Energy has been my game since 1974. Before Google, before Energizer there was Overture and Eveready Union Carbide and I was there and am still here helping people find the power they need for timepieces and every other portable electronic device.

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