One minute on a Seiko QM-20 Marine Quartz Chronometer

Seiko QM-20. A gorgeous semi-vintage quartz marine chronometer.
For demonstration of the beeping when checking battery status.

This video is made for use on a watch/clock forum and thus is not very interesting on it's own. However please feel free to ask questions etc.

For those interested in pictures of the inside of the QM-20 (and QM-11) here's the thread on WatchUSeek:
http://forums.watchuseek.com/f9/show-us-your-quartz-marine-chronometer-movt-5...
The link starts halfway down on page 2 where info about this QM-20 begins. Please also check out the rest of the thread.

A little info on the Seiko QM-20:

According to the book "The Ship's Chronometer" by Marvin E. Whitney with preface written April 1985 - the QM-20 was "introduced just recently" which I on first thought interpreted as around 1985 but can be earlier as I'm a bit mystified by the IC manufacturing dates - and they or the board has not been replaced.

Electrically it's almost identical to the well known almost iconic Seiko QM-10. The QM-20 is the luxury version but technically and performance wise (very?) identical to it's cheaper sister. Back then when such chronometers where used on ships they where tools and as such it's really no surprise why the majority chose the QM-10 the result being that the QM-20 is now quite rare.
The QM-20 is long out of production as is the QM-10. However the QM-10 has been replaced by the QM-11 which is by upload of this video still available. The QM-11 has updated electronics - most likely because the old oscillator is out of production and/or the older QM-10 used through hole components where as the QM-11 is modern SMD - but other that that only minor changes to the mechanical part of the movement and exterior color scheme. Performance wise the QM-11 is for all practical purposes identical to the older QM-10 despite oscillator technology is vastly different.

There you'll also find a bit of information about the internal backup battery which keeps the chronometer running during battery change.
And more importantly - why it's a good idea to either just remove it or replace it if you absolutely want it to have a backup battery once it has reached 10-15 years of age. IMHO backup is not really necessary in a collectors possession. Old NiCd/NiMH cells _will_ leak with time and if left unattended the extremely corrosive electrolyte will ruin the electronics - and before you now it to the point of unrepairable. Even if you're not using the clock they'll leak although leaking is more pronounced when in use because of higher internal pressure in the cells. Think of it as your car. You (or your mechanic) also change the toothed belt before it fails. Because if it fails your engine is instantly wrecked.

If anyone has a (scan of the) manual for the QM-20 I'd be very happy.

Yes my floor is a bit uneven ;)

Category:

Science & Technology

Tags:

• Seiko
• QM-20
• marine
• chronometer
• quartz
• crystal
• clock
• vintage

[HifiCentret]

@djpeebs If you like please join us over at WatchUSeek and the HAQ forum. I and I presume many others are eager to see pictures of the inside of yours too. It just struck me. The lower battery life of your QM-10 could also be because of leaked backup batteries. They was leaked in mine but I repaired that. Now running without but plans to put in a super cap. instead.

Enjoy your chronometers. Such great quality clocks are no longer made. Only some that resembles (like QM-11 etc.)

[HifiCentret]

@djpeebs I did write the styling is different but I made that more clear. What's as good as identical is the electronics inside. Take a look at WatchUSeek in their High Accuracy Quartz forum where I have pictures of the inside of this one and others have of their QM-10. Maybe you have a particular early version of QM-10 ? Runtime should also be identical - again unless you have a less comon QM-10.

[djpeebs]

I own one too as well as a QM-10. The comment above about being "almost identical" is false as they both have radiclly different styling. The QM-10 has a distinctly '70's feel to it, particularly in the style of the numerals. The QM-20 has a much simpler and cleaner and look and feel. It's detailing is much more luxuriously appointed than it's older sibling. Finally, if you put three brand new D batteries into each chronometer at the same time, the QM-20 will run significantly longer.