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Seiko 7A38 Repairer ?


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Yes, by all means do. You have a 15 minute window to edit / delete it, once you've posted.

However, before I commit to having a look at it, would you mind posting a photo of it please ?

I'd like to see a good clear in focus photo of the dial, especially ....

That should give me an indication of the general condition of the movement.

If the lume pips or hands are significantly discoloured, or there is staining around the sub-dials,

it usually means previous battery leakage or water ingress.

the time and day date work fine but the stop watch functions dont.

Either of which, with your watch's symptoms might indicate the need for a replacement circuit board.

Which I have - but not 'spare' for use on other people's 7A38's.

I was thinking of this previous thread, worth your reading: Seiko 7A38-7280 Looking Sorry For Itself.

Edited by SEIKO7A38
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Yes, by all means do. You have a 15 minute window to edit / delete it, once you've posted.

However, before I commit to having a look at it, would you mind posting a photo of it please ?

I'd like to see a good clear in focus photo of the dial, especially ....

That should give me an indication of the general condition of the movement.

If the lume pips or hands are significantly discoloured, or there is staining around the sub-dials,

it usually means previous battery leakage or water ingress.

the time and day date work fine but the stop watch functions dont.

Either of which, with your watch's symptoms might indicate the need for a replacement circuit board.

Which I have - but not 'spare' for use on other people's 7A38's.

I was thinking of this previous thread, worth your reading: Seiko 7A38-7280 Looking Sorry For Itself.

Mine looks better than that one. Tried including a photo but got error message saying I could not use that 'extension' If you email me I will reply with photo attachment ss1_1aa@hotmail.co.uk

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However, before I commit to having a look at it, would you mind posting a photo of it please ?

I'd like to see a good clear in focus photo of the dial, especially ....

That should give me an indication of the general condition of the movement.

If the lume pips or hands are significantly discoloured, or there is staining around the sub-dials,

it usually means previous battery leakage or water ingress.

As requested, Bruce kindly emailed me a photo of his 7A38-7280 this morning ....

It's actually a two-tone version, as opposed to the stainless white-faced version:

Seiko_7A38_close_up.jpg

The dial / sub-dials / lume look nice and clean, so that's a good start. :thumbsup:

Before we go any further, though, could we try a little 'self-help' tutorial first ? :smartass:

.... the time and day date work fine but the stop watch functions dont.

The reason I'd like to go through the following steps is that ....

in my experience, it's very unusual for ALL a 7A38's chronograph functions to be totally dead (and the watch still be working).

First, please check if the crown is pushed fully home. It's pretty obvious thing to do, but ....

Comparing yours with my own identical 7A38-7280 in my hand, your crown seems to be sticking out just a little bit more.

Next step. Pull the crown out to the second click, and push it back (fully) home again. Did any of the chrono' hands move ?

The ones you're looking for (any sign of) movement (even 'trembling', but not advancing) are the central sweep second hand,

and the sub-dial hands on the 9 o'clock (30 minute) and 3 o'clock (1/10 second) registers.

Taking it one step further ....

With the crown pushed fully home, depress the pusher button at 4 o'clock, and hold it there for two or three seconds.

This is the 7Axx's in-built chrono' function self-test. The three hands I mentioned above should complete one revolution.

I'll wait to hear back from you, before we go any further. :wink2:

Edited by SEIKO7A38
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Comparing yours with my own identical 7A38-7280 in my hand ....

Which I don't think I've ever previously taken / posted any photos of before. :blush: So to quickly remedy that situation ....

a couple of very Q&D photos I rattled off this afternoon. :photo: They don't really do the watch justice. It's as good as mint:

7A38-7280-StainlessGold-SilverGreyFace-Mine-P1070007-Resized.jpg

7A38-7280-StainlessGold-SilverGreyFace-Mine-P1070008-Resized.jpg

The painted sub-dial rings haven't faded (in the lower photo), they're just more difficult to capture in bright sunlight. :wink2:

Edited by SEIKO7A38
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After trading a couple of emails, Bruce posted me his sickly 7A38-7280 yesterday. It arrived safely, late this morning.

You'll have to excuse the quality of some of the following photos, the available natural light was at best 'variable' today.

7A38-7280-P1070150-Resized.jpg

First off came the obligatory watch-case / bracelet strip and clean.

At first glance it looked clean-ish, but there was years of hidden muck.

Sorry, Bruce, but you could have probably grown something in the lug box. :yucky:

7A38-7280-P1070151-Resized.jpg

The case back was loose, only on finger tight, and showed prior evidence of regular battery changes:

7A38-7280-P1070154-Resized.jpg

First (dull and grainy, due to poor light) photo of the movement looked promising (lug box muck now mostly scraped out !)

7A38-7280-P1070152-Resized.jpg

Here's another taken by flash:

7A38-7280-P1070153-Resized.jpg

There was little or no visible evidence of past battery leakage nor moisture ingress. :thumbsup:

However, there is a sign of the primary cause of one of the chrono's problems, right in the middle of that photo. :thumbsdown:

Could be a thicker crown, the underside is about 10 thou. off the case.

Something else visible in that photo, is what made the crown appear to be sticking out more, in Bruce's original photo ....

The crown post (not the stem) is slightly bent. :( I didn't think it worth fitting a replacement NOS crown at this stage. :thumbsdown:

Edited by SEIKO7A38
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.... the time and day date work fine but the stop watch functions dont.

One of the reasons for the lack of chrono' functions was the sheer amount of muck compacted behind the pushers. :yucky:

Before it went anywhere near my ultra-sonic tank, I scraped out the worst with a cocktail stick. This is just one pusher:

7A38-7280-P1070155-Resized.jpg

The watch-case was then stripped and cleaned (I fitted a new crystal, gratis at the same time) ....

Once it was all dried, I greased and re-fitted the pushers - but I haven't replaced any of the seals.

I then turned my attention to the movement. As I wrote in my email, someone has had a go at this before me ....

and they don't appear to have been exactly gentle ! Look at the second photo of the movement again ....

and you'll see that the the end of the finger tension spring is dimpled. It should actually be dead flat.

At some time in the past, someone, for whatever reason, has pulled the main hands on this watch ....

7A38-7280-P1070156-Resized.jpg

.... and been rather heavy-handed in replacing them - hence the very deep dimple in the finger tension spring. :hammer:

7A38-7280-P1070157-Resized.jpg

Edited by SEIKO7A38
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While I had the movement out of the case, I nudged the chrono' hands around gently with a cocktail stick.

When you do this, you can feel some feed-back from the gear-train, and the residual magnetism in the rotor stator.

Or at least I could with the 1/10s and 30 minute sub-dial register hands on your watch ....

Unfortunately the chrono' sweep second hand had no feedback whatsoever, and felt very limp.

Movement reassembled back into the case after lunch and Hey Presto ....

Both the 1/10s and 30 minute registers now work (both in chrono' mode and self-test):

7A38-7280-P1070158-Resized.jpg

7A38-7280-P1070159-Resized.jpg

So after a self-congratulatory ciggie and a cup of coffee :smoke:, I set about finding the other problem.

As you can see from this photo, the pusher actuator levers which you suspected were all quite clean:

7A38-7280-P1070160-Resized.jpg

Note that I hadn't bothered to replace the finger tension spring. Next, removing the centre chrono' seconds bridge:

7A38-7280-P1070161-Resized.jpg

Nothing immediately obvious, apart from possibly some wear to the central jewel (although the gears were meshed).

There was some light scoring on the shaft of the chrono' seconds wheel:

7A38-7280-P1070162-Resized.jpg

Edited by SEIKO7A38
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Eagerly waiting for the next update....

There may not be one. :(

To quote Harry Callahan:

I've only ever dismantled the main train wheel bridge once. It's an absolute b*st*rd of a thing to get back together.

Fourteen pivots to line up (at once). Not the sort of task I relish myself - especially on someone else's 7A38.

I'm going to try something else tomorrow. Failing that, it's over to Roy - or another proper watchmaker. :grin:

Edited by SEIKO7A38
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I do enjoy a tear down, especialy when it's not me doing the pivot alignment :hammer:

as it has 4 coils with two different part numbers (2 pairs?) does this mean that there is a seperate one just for the chronograph seconds? if it does have it's own coil is it worth swapping it with the other matching one to see if the main hands stop and the chrono seconds starts working.

please excuse me if I'm talking utter nonsense, it's late and I'm rather full of red wine :wine:

wookie

Edited by wookie
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as it has 4 coils with two different part numbers (2 pairs?) does this mean that there is a seperate one just for the chronograph seconds?

if it does have it's own coil is it worth swapping it with the other matching one to see if the main hands stop and the chrono seconds starts working.

Please excuse me if I'm talking utter nonsense ....

You're not, Wookie. In fact, I'm already one step ahead of you. :wink:

P1070161-ProblemAreas.jpg

Yesterday afternoon, I had already tried swapping the sweep second hand coil. It's the one with the red arrow.

I didn't swap it for one (the H.M.S.) off this movement, but another known 'good used' spare one from my bits box.

Sorry, I'd forgotten to mention that. :blush: Made no difference anyway. :sadwalk:

Just in case it was a fault on the PCB (which was spotless), I also swapped that for my 'gold' NOS one, too. :thumbsdown:

The actual components of the chrono' seconds gear train in the main bridge are minimal.

They're the 3 wheels within the yellow rectangle. Obviously the main wheel is removed.

Then you've got the intermediate seconds wheel and the (geared) rotor. That's it !

Problem is, to replace either of the latter, you've got to remove that bridge. :fear:

I'm going to strip off the PCB and '710' spacer again, and with the seconds bridge in place, try and see (with a loupe) :blind:

what is going underneath, as I move the sweep hand though one revolution.

Edited by SEIKO7A38
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as it has 4 coils with two different part numbers (2 pairs?) does this mean that there is a seperate one just for the chronograph seconds?

if it does have it's own coil is it worth swapping it with the other matching one to see if the main hands stop and the chrono seconds starts working.

Please excuse me if I'm talking utter nonsense ....

You're not, Wookie. In fact, I'm already one step ahead of you. :wink:

P1070161-ProblemAreas.jpg

Yesterday afternoon, I had already tried swapping the sweep second hand coil. It's the one with the red arrow.

I didn't swap it for one (the H.M.S.) off this movement, but another known 'good used' spare one from my bits box.

Sorry, I'd forgotten to mention that. :blush: Made no difference anyway. :sadwalk:

Just in case it was a fault on the PCB (which was spotless), I also swapped that for my 'gold' NOS one, too. :thumbsdown:

The actual components of the chrono' seconds gear train in the main bridge are minimal.

They're the 3 wheels within the yellow rectangle. Obviously the main wheel is removed.

Then you've got the intermediate seconds wheel and the (geared) rotor. That's it !

Problem is, to replace either of the latter, you've got to remove that bridge. :fear:

I'm going to strip off the PCB and '710' spacer again, and with the seconds bridge in place, try and see (with a loupe) :blind:

what is going underneath, as I move the sweep hand though one revolution.

I,m just going for a fag and a cup of tea while I wait for the next installment very interesting post. :notworthy:

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I,m just going for a fag and a cup of tea while I wait for the next installment very interesting post. :notworthy:

I've just had one :smoke: and a cup of coffee while waiting for the postman not to deliver my next incoming 7A38. :sadwalk:

So I guess it's back to the 'drawing board', and this particular errant 7A38. :hammer:

Edited by SEIKO7A38
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I'm going to strip off the PCB and '710' spacer again, and with the seconds bridge in place, try and see (with a loupe) :blind:

what is going underneath, as I move the sweep hand though one revolution.

I was of course talking complete and utter b*ll*cks, because even with a loupe :eek:, it's almost impossible to see:

7A38-7280BBP1070163-Resized.jpg

7A38-7280BBP1070164-Resized.jpg

But I did establish that the sweep hand was indeed turning the second wheel; second intermediate wheel and rotor. :)

Having re-assembled this for what must now be the fifth time, I now have the beginnings of a 'tremble' in the sweep hand.

It doesn't rock back and forward very far, but there is life, Jim - but not as we know it.

Not on any single occasion has it made it between two second markers without gentle assistance from a cocktail stick. :(

However, what worries me more, is that there is still zero (notchy) 'feel' as you nudge the sweep hand around the dial.

Worse still, when you do, there is very noticeable lateral play in the hour and minute hand posts. Not good. :thumbsdown:

This obviously has something to do with what Bruce wrote:

Pulled the crown out to 2nd stop and only the minute hand moved back slightly.

Tried again and not even the minute hand moved.

Hope this helps with the fault diagnoses.

Yet strangely, overnight, the watch has kept perfect time - almost to the second. Just shows you how tough 7Axx's are.

I suspect that there is some internal damage to the main gear train and base plate jewels which is allowing this lateral play.

Obviously not entirely un-connected with this:

At some time in the past, someone, for whatever reason, has pulled the main hands on this watch ....

.... and been rather heavy-handed in replacing them - hence the very deep dimple in the finger tension spring. :hammer:

Edited by SEIKO7A38
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O.K. This is where I'm going to admit defeat. :blush:

I tried to call someone I know who works at Seiko UK, for advice / confirmation, but no-one picked up the workshop phone.

So I called Steve Burrage at Ryte Time, and asked him for his opinion.

Steve hasn't done that many Seiko 7A38's, but has plenty of experience in re-building 7A28 RAF Gen. 1's.

I decribed the symptoms to him, and he said that if someone had been very heavy handed in re-fitting the main hands

.... it's possible that they have disclocated or cracked a jewel in the main plate - or at worst bent the plate. :hammer:

Because the main centre wheel and pinion are no longer properly located (hence the lateral slop in the hands) ....

It's more than likely that the Chrono' seconds wheel's shaft is binding on the inside of the tube which explains ....

Nothing immediately obvious, apart from possibly some wear to the central jewel (although the gears were meshed).

There was some light scoring on the shaft of the chrono' seconds wheel:

7A38-7280-P1070162-Resized.jpg

I'm not prepared to dismantle and (attempt to) re-build the main train wheel bridge (on someone else's 7A38). :fear: Sorry. :sorry:

Steve Burrage quoted (me) £75-80 for such a re-build. I'd suggest that given the value of the watch, it's probably not worth it.

Or of course, naturally ....

You could try Roy

Failing that, it's over to Roy - or another proper watchmaker. :grin:

Edited by SEIKO7A38
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.... I now have the beginnings of a 'tremble' in the sweep hand.

It doesn't rock back and forward very far, but there is life, Jim - but not as we know it.

Because the main centre wheel and pinion are no longer properly located (hence the lateral slop in the hands) ....

It's more than likely that the Chrono' seconds wheel's shaft is binding on the inside of the tube which explains ....

As a further sanity check to this sad conclusion ....

I've since tried operating the chrono' with the hour and minute hands in different positions ....

And in some positions - quel surprise not - there is absolutely NO movement, not even a tremble from the sweep hand.

So perhaps when I had earlier seen some slight sign of movement before (around lunchtime), that was just a lucky fluke.

Sorry to disappoint, Guys. :sorry:

Edited by SEIKO7A38
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.... I now have the beginnings of a 'tremble' in the sweep hand.

It doesn't rock back and forward very far, but there is life, Jim - but not as we know it.

Because the main centre wheel and pinion are no longer properly located (hence the lateral slop in the hands) ....

It's more than likely that the Chrono' seconds wheel's shaft is binding on the inside of the tube which explains ....

As a further sanity check to this sad conclusion ....

I've since tried operating the chrono' with the hour and minute hands in different positions ....

And in some positions - quel surprise not - there is absolutely NO movement, not even a tremble from the sweep hand.

So perhaps when I had earlier seen some slight sign of movement before (around lunchtime), that was just a lucky fluke.

Sorry to disappoint, Guys. :sorry:

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