• Upcoming updates
    Over the next couple of weeks we will be performing software updates on the forum. These will be completed in small steps as we upgrade individual software addons. You might occasionally see a maintenance message that will last a few minutes at most.

    If we anticipate an update will take more than a few minutes, we'll put up a notice with estimated time.

    Thank you!

Early Quartz Testing

Garfield

Registered User
Dec 29, 2021
117
31
28
62
Country
I have a mid 80's Seiko 7A38A movement currently in pieces waiting on spare parts from Japan (was dropped from height - a pinion is broken off a rotor, crystal shattered, pusher damaged and there is also corrosion damage). I have sourced all the parts so they are not the problem.

Reading Seiko's data / manual they say to check accuracy using the '10 second gate' presumably on a Seiko tester, there is an adjuster present. I don't have a Seiko tester but I do have a very high spec Tektronix oscilloscope. At some point I am going to need to set the time / rate on this watch so I need to know what the '10 second gate' is / was / does so that I can replicate - would this be some sort of pulse count through an induction loop with the 10 second gate providing the scale ?.

Or is the Seiko tool going to be the only option - these are harder to find than spares for the 80's watches.
 

Chris Radek

NAWCC Member
Apr 13, 2014
1,248
709
113
Lincoln, NE, USA
timeguy.com
Country
The "gate" just means to count the rate over that time period. A longer gate gives you a better reading. Many quartz testers will reliably show the rate to 0.01 seconds/day (once calibrated) because they have crystal ovens etc. I would be surprised if you could calibrate to even 1 sec/day with a scope.

If you don't have a special machine, no problem, just let it run 24 hours and note the offset. If you can't tell for sure if it's fast or slow after a day, it's fine!
 
  • Like
Reactions: John Runciman

Garfield

Registered User
Dec 29, 2021
117
31
28
62
Country
I shall do that, may need to do more than 24 hours though there are only 6 poositions for the adjuster, each position is plus or minus .26 sec per day.

The trimmer presumably acts on the divider that generates the 1 sec pulses - they do say this shouldn't be done under a light but it is pretty hard not to since the case has to be open to adjust it - your periodic method will work for that too.
 

John Runciman

NAWCC Fellow
NAWCC Member
Aug 13, 2003
651
161
43
Seattle, WA
Country
Region
Unless you really obsessed with super accuracy it basically just doesn't matter. As because even a quartz watch when it's in a accurate is so much more accurate than most things we have. For instance if you look at all timing machine like witschi the use it have a setting four seconds per month.

The trimmer
If you read the wording of the Seiko tech sheet it has a switch it doesn't have a trimmer. It's probably using some form of logic regulation and that's why it's specifying a much longer gate times and usual.

Seiko quartz regulation.JPG
 

Garfield

Registered User
Dec 29, 2021
117
31
28
62
Country
As I mentioned only 6 positions - all the 7A38 I've seen they're in the middle, the one I have no different, ignore the condition of the plates - there is quite a bit of water damage in the battery area, I am not sure of the circuits integrity but only when I get it back together will I know. I'm waiting on some parts from Japan.

IMG_1607.jpg
 

praezis

Registered User
Feb 11, 2008
601
89
28
Germany
Country
Region
Hello,
according above data table, adjusting is useful only if the error is more than 0.13 s/d.
So you will have to wait for 1 week at least: if your watch deviates more than 1 sec then, you may adjust (1s/7 days = 0.14 s/d).

Frank
 

Forum statistics

Threads
179,141
Messages
1,571,334
Members
54,077
Latest member
ACBurke
Encyclopedia Pages
909
Total wiki contributions
3,088
Last edit
Swiss Fake by Kent