Omega 550 Series - Automatic Assembly Messing Up Timing + Amplitude

Finished up a watch, timing was +2 / 220 / 0.3

Installed the auto bridge, timing became something like +400 / 140 / 2

Removed the auto bridge, back to awesome rates

Demagnetised the watch, but both the watch and the auto assembly didn't register magnetism to start with on the Lepsi app - however such a drastic change could only be magnetism I think. The reverser wheel is also failing, but not failed yet

Any ideas before I test illogical things?

I guess my approaches are:
- swap auto bridges with a healthy watch and time both watches
- individually demagnetise the auto bridge

Looking back I think I experienced this before too, get an unexpected rate after assembly, going forward I'm definitely going to time before/after the auto bridge as a controlled experiment, I do wonder whether it's the reverser wheel somehow affecting things - is it possible, maybe not the +400 - but reducing amplitude and causing waves in timing

Never thought of that, but I've tried another auto bridge and timing was good - right now the only logical explanation I have is that the balance assembly and the auto bridge are in love, and when they get together, there's this phenomenon, a spark, that dissipates and normalises over time - you can observe the reducing rate here:



It eventually got down to +40 / 180

I've demagnetised the auto bridge individually a couple of times, and the entire watch together a couple of times, I think it's persistent weak magnetism and my cheap demagnetiser is just not taking it away effectively

Lifting the auto bridge slightly gets the rate in line, so you're right, thank you for the suggestion!

Time to dive into yet another world of hurt

The issue was reducing the amplitude as well - my temporary solution was to just replace the automatic assembly for the time being, others don't seem to cause the issue and I can't see anything apparently wrong with this one yet - after spacing myself a bit from the issue, maybe something was causing this specific bridge to be seated slightly off angle - I've deferred the issue though

Thank you for the suggestion about testing different positions as well, makes sense

220 is what I strive for, I don't replace or service the mainspring and only open up watches if there's a major issue, in this case it was a heavily oiled watch with wrong screws inside, wonky armor ring risking the dial, considering the treatment it got before I'm very happy with 220

Living in Turkey it's pretty challenging surviving inside a self embargoed country, I couldn't find the right sized mainspring tool from Aliexpress (privileged company, only place that can bypass the customs wall) and it just seemed not worth the extra risk to import the right sized Bergeon winder

I really hoped one of the many popular movement winders would be compatible with the 550 barrel, but at one point I checked the sizes and as far as I recall none of them seemed to be