7Axx movement rotary step switch adjustment function

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jamesam
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7Axx movement rotary step switch adjustment function

Post by jamesam »

Off-topic posts moved to start new thread. (Originally posted in Heads Up on yet another 7A38 Franken(s) - Part 3 !!)

Can you educate me on how the missing rotary step switch will manifest itself to someone who casually picks up the watch to see how it works? Thanks in advance.

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Seiko7A38
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Re: 7Axx movement rotary step switch adjustment function

Post by Seiko7A38 »

Where may I ask is the rotary step switch missing in either of the movement photos in my two previous posts ? :?
Oh, but wait, you must be referring to my post of 21st June.
Seiko7A38 wrote: Mon Jun 21, 2021 9:49 am
rsz_7a38-704a-darkgrey-franken-7a38-601ldial-ebay-june2021-10.jpg
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Note the rotary step switch is missing. :roll:
jamesam wrote: Wed Aug 18, 2021 6:20 pmCan you educate me on how the missing rotary step switch ....
Go ahead, be my guest, fill your boots and educate yourself ! :ugeek:

https://www.watchuseek.com/threads/rate ... ph.282347/

7Axx-RateAdjustment-SCWF-WatchUseek-dwjquest-Post.png
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jamesam
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Re: 7Axx movement rotary step switch adjustment function

Post by jamesam »

That was quite a detailed technical explanation....that I tried to read and comprehend. But that was a lot more than my non-technical mind can grasp.

So it was a relief to get to the final sentence that says simply:
“the Seiko 7A chrono series is equipped with a rotary multi stage switch, allowing to adjust between -2 and +3 steps (or -6 and +9ppm), which should be enough to compensate for many years worth of aging”

So I think the answer to my original question is: it won't manifest itself to someone who picks up the watch - a buyer of that watch with the missing rotary switch isn't going to notice anything “not working” when they receive the watch.

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Re: 7Axx movement rotary step switch adjustment function

Post by Seiko7A38 »

Jim. The simple answer is that you probably won't notice anything untoward on receipt, because the watch will still run without it. It's not until the watch later possibly starts gaining or losing time that it has any detrimental effect. If the rotary step switch is missing, you'll discover that you have no facility to correctly adjust the timekeeping accuracy. :(

Losing the tiny gold-plated rotor during disassembly of the movement is a relatively common mistake made by novices and seasoned watch-botchers alike. You will find instances of it cited in a number of forum threads, for example here:
Seiko7A38 wrote: Wed Mar 24, 2021 12:39 pmNote that once again this incompetent botcher claims the watch has been serviced (per his unsold stainless 7A38-7140). This time it's not the rotary step switch that's missing, but the centre seconds finger tension spring ! :lol:
It's just an indicator of general carelessness and clumsiness and another good reason why you should avoid these sellers.

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Re: 7Axx movement rotary step switch adjustment function

Post by Seiko7A38 »

Seiko7A38 wrote: Wed Aug 18, 2021 7:21 pm.... and educate yourself ! https://www.watchuseek.com/threads/rate ... ph.282347/
Unfortunately, since the old archived Network54 SCWF was migrated to Tapatalk, the embedded link to Michael Rothe's erudite post, dating from 2007, in David Johnson's (dwjquest) Watchuseek thread no longer works. I remember it was quite a long thread. Took me a while to find it again, but worth the effort: Seiko 7A38-7000 Trimmer Adjustment.

Michael Rothe's post #17 originally included a number photos, illustrating the switch function in considerable detail, but sadly they've long since disappeared into the ether, along with all the photos from that thread. Here's one such I saved from it, back in the day. I'm not entirely sure where they all fit in relation, but this image likely goes with the caption:
Here is an overlay picture of the adjustment markings and the contact pattern on the circuit block:
7A28_StepSwitchOperation.jpg
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Or it could possibly be an edited version of the same image from Michael's post #20:
I tried to make a see-through picture with the markings, the contact pattern and the rotor.
It didn't come out very pretty (I'm an engineer, not a graphics designer!), but one can see how it works:
Not sure who posted this sequence of settings, or if it came from the same thread, but it's certainly worthy of inclusion:

7A38-RateAdjustmentSteps.jpg
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Edit: Judging by his statement: 'I've adjusted one of my 7A's to +5 secs/month', I suspect it's from Hung Pham's post #2.

I'm absolutely certain where this next one fitted in though (from the embedded link, confirming the thread title) ....

7A38-7000-Gold-TrimmerAdjustment-Network54-SCWF-Post.jpg
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Re: 7Axx movement rotary step switch adjustment function

Post by Seiko7A38 »

That all said, Jim ....
Despite the wealth of information presented to you, not just here incidentally, bothering to take the trouble to read it properly (and sometimes, by your own admission, actually comprehending it) doesn't appear to be your strong suit. :|
jamesam wrote: Thu Aug 19, 2021 4:02 amThat was quite a detailed technical explanation....that I tried to read and comprehend. But that was a lot more than my non-technical mind can grasp.
So if in doubt, the simple answer is to try reading the manual sometime (from top of the 7A28A Tech Manual, page 11):

7A28A-TechnicalManual-Page11-RotaryStepSwitchAdjustment.png
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Re: 7Axx movement rotary step switch adjustment function

Post by Seiko7A38 »

In an effort to collate all available information into this new thread, I also referred back to the old archived website's extremely useful Other Links section, where amongst the interesting attachments and links, I found this small section:

7Axx-RateAdjustment-OtherLinks-Archive.png
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We've already re-discovered the first two, but like the old Network54 SCWF thread (from 2007), the link to that later SCWF post didn't work any more either. :( Ownership of the SCWF was taken over by VerticalScope in February 2013 and was subsequently migrated onto the latest version of their platform in March 2020, at which point everything got re-indexed. So it's extremely unlikely that any of the links I posted to the SCWF on the old forum will still work. :roll:

Fortunately there is a separate SCWF forum section, entitled The Tokunaga Archives, where I found it again, here. :)

7Axx-RateAdjustment-SCWF-Tokunaga-Post.png
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How would 'Master Engineer' Tokunaga finish his reply ? By quoting the manual - just as I had, in my previous post. 8-)

I also found this other SCWF thread dating from January 2016: Adjusting Seiko's 7A38 / 7A28, some help needed.

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