Regulation of 70's Quartz 1345 movement

Hi,
I am new to the Omega watch world having recently bought a 1345 movement 1976 watch. It was sold as an 1342, but has day/date so I believe it is a 1345? I am an electronics engineer by trade and was drawn to this particular watch as it is a genuine Omega designed quartz movement complete with 7 jewels. It is a beautiful mechanical/electronic thing.

I am now trying to regulate it. It is losing around 2 seconds a day. I have tried various positions of the trimmer capacitor and that affects the regulation, but only changing it between losing 3.5 seconds per day or 2 seconds. There are no markings as to which position is slowest or fastest. Any thoughts on that?

In any case I need to adjust by more that this amount so was considering changing what appears to be a fixed capacitor connected across the trimmer. Any ideas what value this is? Is it a capacitor? In the absence of any info, I will remove it and try various small values starting with 10pF. Does that right? Any help greatly appreciated.

Thanks

Mike

Hi Mike! Welcome to the forum!

You can download a parts list for the 1345 (and 1342) here: https://watchguy.co.uk/cgi-bin/files?subdir=Omega&dir=Technical Manuals&action=documents

Info on the recommended device to use while setting the trimmer: https://www.watchrepairtalk.com/topic/6905-omega-1342-trimmer/


I'm curious to hear what you discover.

Best wishes!

Thanks all for your prompt responses! The 1310 pdf is great but the 1345 is quite different to the 1310 movement. A similar PDF for the 1345/1342 would be fantastic. The parts lists don't seem to include individual components on the circuit PCB. I was just looking at the tracks on the 1345 PCB and the small component beside the trimmer looking like a small surface mount capacitor is connected across the trimmer capacitor. So my guess would be this fixed capacitor is chosen in the factory to provide the coarse adjustment to the crystal frequency and then the trimmer is used for fine adjustment and to compensate for ageing. After 45 years the watch is now outside that range of adjustment. This is all conjecture on my part, so advice from anyone who has serviced this age of watch would be great.

From what I've read, if the PCB goes bad, past options have been to send the watch back to the mother ship to have the board remanufactured, or to source a spare, usually from a donor watch. If you can service this PCB yourself, a lot of people might be excited, because it might mean hope for another route to repairing these.

You might also find it helpful to read through the thread I quoted above. Those contributing might be your best resources in your effort:
https://omegaforums.net/threads/my-omega-quartz-delay.127859/