Hello all, Bought this beauty (3520.53.00) recently, mint, papers box, the whole deal. I am delighted to be a fan of the brand now. It is not only my first Omega but also my first automatic chronograph. Being a watch enthusiast I put it in my timegrapher (see data in image attached) and, besides being a little fast, the amplitude looks decent, here is my question how much the amplitude should drop with the chronograph ON?
Hello and welcome - I'm assuming these numbers are taken at full wind - if not then let me know. First comment is that the lift angle is 50 degrees for the Cal. 1151, not 49. The specs you list for the 7751 in terms of Delta, etc. are not necessarily applicable to the Cal. 1151. For example you have the Delta number expressed as +/- 15 seconds, where the Delta tolerance at full wind is just 15 seconds total. The tolerance for average daily rate for the Omega version is from -1 to +11 seconds per day, and the Delta increases from 15 to 20 seconds at 24 hours after full wind, so the isochronism tolerance is different than what you have listed, Regarding amplitudes, companies don't often give minimum amplitudes at full wind. They usually give a maximum that is related to the risk of rebanking. So for looking at an amplitude tolerance, this is typically given at 24 hours after full wind, and as you have listed that is 200 degrees - this is measured with the chronograph off by the way. The amplitude drop should be no more than 30 degrees when the chronograph is engaged according to Omega specs, and you have 40, so it's out of spec. This could be related to movement condition (needing service) or it could be that the engagement between the oscillating pinion and chronograph runner needs adjusting. If you don't know the date of the last service, you should consider getting a service done on the watch. Hope this helps. Cheers, Al
Archer, thanks so much, I set the correct lift angle and got the data just now (24hrs after winding it) and got slightly better results. Amplitude drops on average 35 degrees when the chrono is on. Looks like is slightly off specs so will take it to my watchmaker to have it checked out.
I was able to find the cal. 1151 technical guide, and it states that max loss witch chrono on is 40 degrees. So looks like my watch is just fine and perhaps just needs a regulation. I found a couple of revisions to this technical guide but there are no changes in the amplitude, mostly updated lubricants info and graphics of the movement.
That's an older guide - the technical guides no longer list such information. That is found in Work Instruction 28, which is where the specs I quoted you are from. By current Omega standards, the drop should be no more than 30 degrees. Cheers, Al
Archer, this is so interesting, the updated tighter specs are probably due to better lubricants, right?