Reply With QuoteI've dug out an old but running ETA 2783. I know some parts are the same but many are not. Let me know if this might do the trick.
Long shot but I`ll give it a try:
I'm looking for an ETA 2784 movement to help with a repair job, the watch in question needs several parts. Thought these were easy to find but it appears not, ETA made 2 ranges of movements with 21600 and 28800 beat rates respectively, turns out all the parts I have are for the wrong one!
Anything considered, a non-runner will be fine but the balance must be good.
I've dug out an old but running ETA 2783. I know some parts are the same but many are not. Let me know if this might do the trick.
The 2783 runs at 21600bph, the 2784 runs at 28800, unfortunately the balance (which I need) isn’t interchangeable so it’s no use. Thanks for the offer.Originally Posted by SplitSecond
Every day's a school day!
My knowledge of the earlier ETA movements from the 70s is vague, there were lots of variants but the designs are very similar. The watch I received yesterday, a 70s Helvetia, is running a 2784 11.5 ligne movement and unfortunately it's in poor condition, the balance and balance cock appear to be from a later 2824 and the balance is running with excessive endshake because the later movement is fractionally shallower in that area. I knew I had parts from a similar movement but that turned out to be a 2783. When I started reading up (Ranftt pink pages) it becomes clear that the 2700 family had two major variants, some run at 21600 bph and others run at 28800. Interchangeability of parts becomes complex, get it wrong and a movement will give good figures on the timegrapher but run way too fast or slow, obviously the balance (which I need) isn`t interchangeable but I`m not sure about the mainspring barrel, parts numbers differ but that isn`t always definitive, measuring the two with a digital caliper and counting the teeth is the way to be sure.
Basically, the 2783 and 2784 have the same dimensions, but different beat rates (21600 and 28800 respectively). There's a whole list of variants but they fall into one of two categories.
Thankfully, from what I can tell, the later 2824 auto-winding parts will fit, the bridges seem interchangeable and so do all the parts including the rotor, I didn`t know this but it's useful to know.
Unfortunately parts for these movements are now getting scarce, they're either discontinued or (frustratingly) supply is restricted by Swatch Group. That's forcing second-hand prices up. These movements were used in huge numbers during the 70s, I assumed plenty of second hand stuff would be available easily, but that doesn`t seem to be the case.
The joys of fixing old watches! As for Swatch Group restrictions, who the hell do they supply ETA parts for a Helvetia to?
If anyone turns up an old ETA 2784, 2771,2774, 2780,2784 or 2790 I'm interested!
http://www.ranfft.de/cgi-bin/bidfun-...2uswk&ETA_2784
Last edited by walkerwek1958; 10th May 2023 at 11:46.
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