The watch is a Bell & Ross BR03-92, it has a "calibre BR-CAL.302" inside, which is really a Sellita SW300, which is a clone of the ETA 2892, a proven and reliable movement.
This watch was introduced at Baselworld 2019 and the serial number is very high, it was right at the end of the production run so age shouldn't be a problem, it won't have been sitting lost and unloved for a significant period of time and was bought brand new from an AD.
Timekeeping then, over the first 2.5-ish days, the watch lost an average of 22.9 s/d, not acceptable. The calibre specs aren't easily found so I emailed B&R to find out what the timekeeping specs should be, they were very cagey about this, it took me several attempts to get them to commit to an answer but they finally told me 0 to +10 s/d. Obviously -22.9 is quite a way outside this.
I reset the time and started again, the watch lost 25.3 seconds over the next day and I decided to just send it back. Timekeeping was consistently bad in all positions, no matter how I placed the watch it didn't vary significantly.
I packed the watch up, ready to drop it like hot sh*t and let the power reserve die. Next day, I hadn't been able to get to the post office so I started the watch up again and the damned thing kept perfect time over the next 48hrs!
Cool, problem solved, perhaps a small knock in transit gave it a little wobble, it seems to have solved itself...
Until last night when it started losing time again, we're now at 8 seconds lost since last night, back again to a rate of around -24 s/d.
What's going on? Have I got a Friday afternoon lemon?
I'm no expert on movements but that doesn't sound right at all so definitely send it back to be looked at. My IWC Mark18 has the same movement and is +/-0 when on wrist at high wind. Timekeeping tapers off at lower wind but only to -2 secs per day maximum. I realise that IWC may do something to the movement but this is what it's capable of and yours really shouldn't be off as much as it is.
Have you checked if it’s magnetised ?
Sorry if stupid question, but try holding a simple compass near it for a reaction.
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That doesn’t work in a case, you have to take the movement out. It’s under warranty, so just send it back and save worrying about the why. Unless you are capable of disassembling it, don’t worry about it.
You don't need to remove from the case to use a demagnitiser.Originally Posted by me32dc
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Err.. you sure. I’ve never done that.
Yeah, I've had a few with the same movement inside and none have ever had timekeeping as odd as this.
I've been in touch with the AD, it is going back to them tomorrow, I'll decide between now and then whether I want to get it repaired or refunded.
Yes, you need to know if the critical parts are magnetic mainly the escapement and hairspring. Knowing one small part of the case is magnetic may have no effect on the watch at all.
As for de magnetising in a case, all service centres demagnetise the movement outside the case. Before regulating and putting in beat.
The case is ceramic.
Still you are doing the right thing sending it back and not trying to diagnose yourself.
Demagnetising on the cheap coil demagnetisers is not easy and you can destroy a hairspring.
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