Seiko 7S26 amplitude

[jackie01]

Hello,

I recently serviced Seiko 7009 with 7S26 movement. Watch was general in poor condition, movement was dirty and there was no oil on jewels. Timegrapher had dificculty to read the amplitude and beat error but visually amplitude was very low. I took it on my bench, cleaned and oiled with Novostar B oil. After that amplitude wasn't satisfactory circa 200deg. I read on net that this movement has generaly problem with amplitude. Besides it get quite good accuracy I could leave it but... I took a look of the balance hairspring - little bented and I think there could be problem. I don't have too much experience and skills with work on the hairspring but I tried to get it better shape. It took me almost 2 hours and I had to take off the hairspring few times. It's not perfect shaped hairspring now but it's better then it was. After that I put the movement on the time machine, look guys what I managed to achieve.

Glass up

 

Glass down

 

I think it's quite good right now. I decided to leave it at this moment. What do You think? Is the Novostar B is right oil for this caliber for everywhere use? Should  pallet fork jewels be lubricated or only the pallets? I'm looking forward Your opinion cause I am a beginner and aprecciate good advices. Thanks

 

[jdm]

There are very many threads which report this problem, it is common with old 7S26. I recommend that you heavily use the search function, to find about that and more  e.g.. that you never oil the escape wheel pivots, that you need (at very least) two types of lubricant, etc.

About your specific problem you will read even after my posting here about the usual suspects, some a

• imperfect dirty or magnetized HS (in reality magnetized HS doesn't cause poor amplitude, but there is always someone that will suggest that anyway)
• dirty balance jewels
• bent balance pivots
• too tight balance handshake
• weak mainspring

You may also read that the fault is because of something you do wrong, and these Seiko can be made oscillate 300°. I disagree with both points.

I can instead ensure you that there is a very high possibility that you go over these points for many hours without applicabile improvement. Replacing balance complete may give you better chances, but that is (relatively) expensive if bought new and original compared to a new mov"t with hack and manual winding for little more.

Finally, PC timegrapher is great but if you show waveform only one can't see the overall pattern, that is the screws with two lines which should be close, continuous and horizontal, so you need to post these.

Nitpick, the horizontal main positions are called dial up (DU) and dial down (DD). The others are relative to crown (sometime 12h ) position, like crown up, etc. You need to always test at least crown down.