Should I be worried about my A7750 GMT

[Drulee]

So I had a movement swapped from one case to another, but now it is running 2 minutes every 24hrs. Before it kept near perfect time, and nothing seemed to go wrong during the swap. Does it just need regulating, or is it a sign of impending doom :shock:

It's an A7750 GMT movement. What do you think? And if it just needs adjusting, how can I go about doing this?

Thanks

 

[d4m.test]

2 minutes per 24 is too much... BUT, check it over several days and see if it continues at 2 min per 24 or if it becomes erratic.
If it continues at a constant +2 min, then it is possible that the adjustment got bumped while doing the transplant. Ive done that myself a couple times!
If it is not consistent then there is most likely a more serious problem.
If that is the case, check the tutorial and video for adjusting the timing and beat on your 7750. It will tell you exactly how to do it. There is even a video floating around.
It takes some patience, and a really steady hand... But its can be done at home.
Good luck!
T

 

[daytona4me]

I have had movement/case screws cause a movement to stop running (sounds crazy huh!). I have had identical handsets cause the watch to run slow 10 minutes in 24 hours.
I've had a crown stem that was cut to short cause a lot of strain on a movement.. there are a lot of things that can affect your watch, question is,, is it consistent in loosing 2 minutes in 24 hours? If so, you are fine,, if it goes from 2 to 3 and 4 and keeps going south,,, well... I think it's obvious you have a problem.

 

[daytona4me]

lol, looks like cbr is faster on the trigger than I am.

:lol:

 

[d4m.test]

D4M, your a good man!!!! I dont care what LOS says!

 

[Drulee]

lol, looks like cbr is faster on the trigger than I am.

:lol:

I'd say you where both pretty quick

Thanks for responding so fast guys. First off, it's running fast, not slow, so I thought this would eliminate the possibility of gears grinding , screw mucking it up, stem putting strain, or anything that may cause the works to move slower. It has gained almost exactly 2 mins every 12 hrs (not 24 as I thought).

Next, which tutorial. I'll do a search for "regulating 7750", would that bring it up? Or is it not 7750 specific?

Any I'll start looking now.

EDIT: Ok, I found a couple on the 21J, nothing 7750 specific (well one I think, but it just had a pic a screwdriver being stuck in the works :shock: ), and not video. So I just have to move the needle in the negative (-) direction, and just a very tiny bit - in which I should only see it move when using some magnification to look at it. Sound right?

 

[d4m.test]

Here ya go...


viewtopic.php?f=54&t=52513&p=464980&hilit=adjusting+timing#p464980

 

[Drulee]

Here ya go...


http://forum.replica-watch.info/phpBB3/vi ... ng#p464980

Ah, that's better Shows just what my movement looks like, so that'll be a big help. Thanks CBR. Given that it gains 2 mins exactly (nearly) every 12 hrs. would it be safe to say that an adjustment of the timing would fix it? As any friction would cause a loss and not a gain? Anyway, I guess I'll find out in 48 hours

 

[Drulee]

Actually after reading that, it looks like I should see some movement of the needle without a loupe, as I'm adjusting for 4 mins per 24 hrs. Wow 4 mins that doesn't sound good.

 

[d4m.test]

Yes, you are correct... I think that it is entirely possible that the adjustment lever was hit during the transplant.
Here is what I do... so as not to need to wait 12,24 or 48 hours... Especially when off by this much.
Follow the instructions and make the adjustment... make it very small. less than 1mm and MAKE SURE you are adjusting the right lever.
Set the watch with the National Atomic clock. Mark the time on a sheet of paper. In 4 or 6 hours see where you are at and multiply the error by the correct number to get a 24 hour period. If its still fast, adjust again... and again... and again... Until you are within a second for the 4 or 6 hour period (which will be either 4-6 seconds off per 24 hours).
This way you can regulate it much quicker.
Also, dont bother tightening the case all the way... put the watch face up while in test mode...
Let me know how it works out for you!!!


YES, you will need to see the lever move about 1mm for a full 4 minute adjustment. That is pretty far off.
This method was used on the a7750 in my 196 and it has now run +1 second over a week... I got lucky, and the movement is in great shape. but you should be able to get it within a few seconds per 24 hours.

 

[Drulee]

That's what I'd planned to do. I've been measuring it against my computer clock (synched to the atomic clock), or my iPod Touch (synched to the computer) when away from the computer. The lever must have been hit during the swap. Can't do anything now, as I don't have a case back opener handy, but I'll update tomorrow. Thanks again for the help.

Wow, I just had a look at my 192 (Seagull manual wind), which I set and have kept wound since getting it last week, it is spot on +/- 0sec At least something's going right.

 

[sconehead]

Whoa guys, slow down. Could just be a gummed up/tangled hairspring. Dru, try this,remove the caseback and with the watch running aim a couple of puffs at the balance assembly with your dust blower. If the spring is tangled it should free it or dislodge any small debris. Fast running can also be caused by the movement being magnetized as well as the levers being inadvertantly moved.
Try the easy fixes first and then progress... :wink:

edit: Hi Greg , you back on the scene or still busy?

 

[Drulee]

Whoa guys, slow down. Could just be a gummed up/tangled hairspring. Dru, try this,remove the caseback and with the watch running aim a couple of puffs at the balance assembly with your dust blower. If the spring is tangled it should free it or dislodge any small debris. Fast running can also be caused by the movement being magnetized as well as the levers being inadvertantly moved.
Try the easy fixes first and then progress... :wink:

edit: Hi Greg , you back on the scene or still busy?

Good thing I checked in before proceeding with the adjusting I'll give your suggestions a shot later this aft, and let you know. Thx

 

[Drulee]

Sconehead, come to think of it, after the swap was done, it took more than just the usual "tap" to get the movement started again. Had to tap it three or four times, with a bit of a "heavier hand" to get it running again. So it sounds like perhaps something (big dust particle?) may have jammed the hairspring. I'll do the air blowing, and let you know the results.

As far as the magnetizing, I have an old tape deck head de-magnetizer at home - would a few passes of that do the trick?

EDIT: One thing I just realized, that may have an affect on the timing. I've had the watch on its side, with the crown up, when testing the timing. How much would this have made a difference? I'll be keeping it on its back once I've adjusted/air blasted it.

 

[Drulee]

Alright perhaps it has something to do with the mainspring/w

UPDATE

Well, I took sconehead's advice and took the case back off and used a camera lens dust blower to give the wheel/mainspring a couple of blasts of air. I then re-assembled and started it again. Everything was going fine, gaining about a 80 seconds in 12 hours, then about half an hour ago it just stopped. I opened it up again, used the blower to blast a little air at the spring/wheel a few times when the wheel suddenly kicked into action again, and its been running fine since.

What do you think? Is there some particle stuck in there somewhere?

 

[sconehead]

Sounds like the hairspring was gummed up or tangled, remember these watches aren't assembled in exactly 'clean' enviroments like the gen factories, more likely in someones back kitchen. Dru, if it's running ok after a few more days, I'd leave well alone, it was probably just the hairspring tangled up after you were working on the watch...keep us posted... :wink:

 

[Drulee]

Sounds like the hairspring was gummed up or tangled, remember these watches aren't assembled in exactly 'clean' enviroments like the gen factories, more likely in someones back kitchen. Dru, if it's running ok after a few more days, I'd leave well alone, it was probably just the hairspring tangled up after you were working on the watch...keep us posted... :wink:

Actually I chose not to work on this one myself, and I had someone more experienced with DSN stuff and A7750's in general to do it, as I didn't want to screw anything up

Well twelve more hours have passed, and it is still running (phew). It's still a minute or so fast, but I haven't tried adjusting the timing yet, so that's next. I will keep you updated.

What really gets me though, is that the movement that was swapped out - the one that minute and hour hand would stop advancing at between 5 and 7, but the GMT hand would keep correct time after they stopped - has been running strong ever since being put in the other watch. Three days, no hand stoppage, no big time variance (+/- 3 secs), no problem what so ever - go figure.

 

[sconehead]

Could be the handset you've swapped out causing the problem, maybe rubbing against each other, didn't D4M mention something about this?

 

[Drulee]

Could be the handset you've swapped out causing the problem, maybe rubbing against each other, didn't D4M mention something about this?

Wouldn't the rubbing of the hands cause it to lose time, not gain it?

 

[sconehead]

Sorry crossed lines there Dru, I meant on the watch they were originally on. Has the watch you've been having the current problems with calmed down yet?