[wilderbeest]

I've taken apart my HMT Sona and taken some photos - if you are interested.

Review: HMT Sona | Watch Guy

For the money it costs, a great watch!

 

[fatehbajwa]

The movement in the Sona is common to most if not all hand wound HMT'S . I find them to be very robust and see lots of watches which have not been used for ages, spring to life with a simple cleaning/service.

Thanks for the tear down. The close up pictures are awesome.


Sent from my iPad using Tapatalk

 

[TGE]

Very interesting, thank you.

And I agree, cool close-ups. That one focused on the pinion on the escapement wheel is great.

 

[skywatch]

Great photos! Too bad about the barrel screw. Whit a nice little movement that is inside. It gives me a new appreciation of my little Janata (thanks to Fateh, in fact!)

 

[ALAMO]

The movement in the Sona is common to most if not all hand wound HMT'S . I find them to be very robust and see lots of watches which have not been used for ages, spring to life with a simple cleaning/service.
Thanks for the tear down. The close up pictures are awesome.

Sent from my iPad using Tapatalk

Well, HMT is producing only one hand winded men's calibre as far as I now. It is a licensed Citizen, and is very robust and reliable as its ancestor. Good that in XXI century one can catch such a beauties on ebay any time !
wilderbeest - try to use the screw from Seiko 7009 if you have one, it will fit as far as I remember

 

[kramer5150]

awesome!! very informative.
These watches are too well made for me to ignore.... I see one in my near future.

thanks fo sharing

 

[fatehbajwa]

I've taken apart my HMT Sona and taken some photos - if you are interested.

Review: HMT Sona | Watch Guy

For the money it costs, a great watch!

If you could post a picture of the part you need, I can send it across... gratis.

 

[Sodiac]

Nice pics and story! Just a tip: if your camera has a manual white balance preset (most do), put it in the custom preset and snap a photo of a white piece of paper under the same lighting. It will adjust the white balance correctly so you don't get the yellow overcast. This is easy to do and removes the color cast from lighting.

 

[wilderbeest]

If you could post a picture of the part you need, I can send it across... gratis.

That is a very generous offer of you - I've attached a photo of the part. You won't have the click spring by any chance as well - I got a bit negligent after the screw of the main spring winder broke ;-)

 

[fatehbajwa]

PM me a picture of the click spring that you need.

 

[wilderbeest]

If you could post a picture of the part you need, I can send it across... gratis.

So kind of you - PM sent

 

[wilderbeest]

Nice pics and story! Just a tip: if your camera has a manual white balance preset (most do), put it in the custom preset and snap a photo of a white piece of paper under the same lighting. It will adjust the white balance correctly so you don't get the yellow overcast. This is easy to do and removes the color cast from lighting.

I'll try that next time, thanks for the hint

 

[wilderbeest]

It's been some time, but I finally managed to find an "organ donor" for my HMT Sona, so I've put it back together.

http://watchguy.co.uk/reassembly-hmt-sona/

For the money these watches cost, they are a bargain. Solid, well made movement, in a good looking case. What's not to like for £20?

 

[tony1951]

Ouuch!!!

After taking my new pilot watch apart to clean it (I found debris in it coming from the stem tube where there seemed to be some filler) I STUPIDLY managed to drop the movement about 30 cm onto my desk while the stem was fitted........ I was adjusting the hour hand to stop it touching the lume dots and it just slipped.

The stem hit the desk first and snapped off inside the watch.

I have removed the stub, but now have to track down a stem that will fit.

I should have left it alone.

Does anyone have a spare from a scrap watch?

 

[wilderbeest]

Ouuch!!!

After taking my new pilot watch apart to clean it (I found debris in it coming from the stem tube where there seemed to be some filler) I STUPIDLY managed to drop the movement about 30 cm onto my desk while the stem was fitted........ I was adjusting the hour hand to stop it touching the lume dots and it just slipped.

The stem hit the desk first and snapped off inside the watch.

I have removed the stub, but now have to track down a stem that will fit.

I should have left it alone.

Does anyone have a spare from a scrap watch?

Not to worry, I got a winding stem from an HMT Janata - that will probably fit.

Shall I just ship it with the bumper when I do the hands?

Christian

 

[tony1951]

Not to worry, I got a winding stem from an HMT Janata - that will probably fit.

Shall I just ship it with the bumper when I do the hands?

Christian

GREAT!!!

THanks Christian.

I just typed you an email while you were sending that and relayed the whole sorry story again. I am intending to post the bumper back to you tomorrow.

I can't tell you how much I appreciate your offer, both to do the hands and to supply the stem. This sorry tale shows why YOU should fit the hands to the bumper and not me. It isn't that I can't do it, it is what else I might do while trying to.

)

Actually, I just read the question there in your post. Could you send the stem (and crown) in the post before that? I want to get the Pilot back to health.

Be sure to add the item to my bill for the hands work.

Thanks

 

[Kevan]

My grandfather was an amateur watch-repairer, and I wish I had gotten into watches while he was still alive so I could fix my own stuff like you guys.

I recently got an HMT Jayanth (thanks Fateh!) that was working for 3 days until I tried to re-set the watch and pull the tiny crown. Long story short, my finger slipped and I think I pulled a little too rough, because now the dial moves when I turn the crown. And while the hands move, it feels like the crown loses traction at some point during a full rotation and spins freely for a few turns, before "grabbing on" again. The watch will run for about 20 seconds at a time before stopping. HMT is my first foray into mechanical watches so I don't know what's going on.

Trying to decide if this is worth servicing, since I have two sterling Janatas that work wonderfully and a Sona on the way.

 

[wilderbeest]

My grandfather was an amateur watch-repairer, and I wish I had gotten into watches while he was still alive so I could fix my own stuff like you guys.

I recently got an HMT Jayanth (thanks Fateh!) that was working for 3 days until I tried to re-set the watch and pull the tiny crown. Long story short, my finger slipped and I think I pulled a little too rough, because now the dial moves when I turn the crown. And while the hands move, it feels like the crown loses traction at some point during a full rotation and spins freely for a few turns, before "grabbing on" again. The watch will run for about 20 seconds at a time before stopping. HMT is my first foray into mechanical watches so I don't know what's going on.

Trying to decide if this is worth servicing, since I have two sterling Janatas that work wonderfully and a Sona on the way.

How about starting now? An ideal candidate for your first foray into watch repair!

Not really worth having it fixed as the bill will be higher than the value of the watch I'm afraid.

 

[tony1951]

Trying to decide if this is worth servicing, since I have two sterling Janatas that work wonderfully and a Sona on the way.

It is likely that there is nothing much wrong, I think. Perhaps you have dislodged the stem slightly. Does it come right out, or is it still fixed inside the watch?

If you remove the back of the watch, it will look like this.

Look at about the nine o'clock position on that white spacer ring that surrounds the watch. You can just see a silver button, or part of it, under the white spacer ring where my red arrow point is. It is mostly covered by the ring in the photo, but if you remove the ring - it should just pull out, you will see a tiny silver button with a depression in the centre of it. The button is spring loaded and the other side of the button works on a lever which locks the stem in place inside the watch. If you press on this button with a stiff pin ( any sharp pointed tool will do - just put it in the depression in the button and press a little) you will be able to either withdraw the stem from the watch, or push it back into place.

NB - when pressing down on the release pin with the watch movement in its case, place a firm pad under the watch glass so you don't scratch or crack it on a hard surface while pressing down on the button.

When you are pushing the winding stem back in, try twiddling (rotating) it slightly, and it should just click into place. I think the watch should then wind normally and set the pointers to time as you would expect.

If it doesn't wind, try applying a tiny amount of fine grade oil, applied with a pin, or pointed tool to the place where the teeth of the transmission wheel and the teeth from the tiny winding wheel on the stem (just follow the red arrow direction to where it meets the teeth on the transmission wheel).

The next photo shows you what is happening on the dial side of the watch. You probably won't want to go there yet, but you will understand how the winding works if you check this photo out.

Look at where the stem enters the watch and see how it engages with a small ratchet and a toothed wheel. The red arrow in the next picture points to the wheel.

That toothed wheel engages on the other side of the watch with the small transmission wheel I showed you in the last picture. The marked wheel above is driven (wound) by the tiny ratchet wheel via a square shaped part of the stem. The fault you have described is to do with the way these parts are working and is not likely to be terribly serious or hard to fix.

I would suggest you can probably sort it out without taking the watch out of its case by doing what I described. DON'T put loads of oil onto the wheels, if fiddling the stem in and out doesn't work, a tiny bit of oil on the stem and wheels as indicated should sort it out unless that part of the mechanism is clogged up with dried out grease.

Going further into the watch than I have suggested will need tools you probably don't have and risks making problems worse if you have never done this before.

How you remove the back of the watch depends what sort of case you have. That varies much more than the actual movements which are mostly the same. My watch has a press on back. It is a tight fit, but there is a little tang that you can get a sharp bladed knife under and twisting the knife, will force the back off.

PS -

I am a beginner as you can see by reading how I broke my stem the other day. Maybe some one better qualified will come along shortly and give better advice.

 

[1839cc]

It could also be a screw on back like this:

If that is the case, you can get a tool to grab it in those little detents around the edge and twist it off. The tool is not expensive, but if the back has not been screwed very tightly you might be able to turn it with a pin or even a fingernail.