Bulova: Cal.Val23 (Valjoux 23)
Symptoms: Poor accuracy
Repair contents: Overhaul, hairspring correction, case cleaning
Repair cost: 33,000 yen
This is an overhaul of a consignment item listed on our online shop. It is a Bulova chronograph that appears to be from the 1960s. The movement is a Valjoux 23, a hand-wound two-counter chronograph. The case is 18k gold and is compact in size.
This is the condition before the overhaul. Although it is not clear from the photo, the balance spring has become deformed and is touching the second wheel. This is causing the watch to advance abnormally.
Before the fix
After correction
Although there seems to be almost no difference when compared, the circumference, or rather the angle of wrapping, has been changed. First, the shape is adjusted to a certain extent, and then fine-tuned after assembly.
Older models often have deformed hairsprings, and it takes a long time to bring them back to a certain level of accuracy. The original accuracy is also different from that of current models, so the tolerance range is wider.
Disassembled
Assemble
Some movements from this era do not have a shock-resistant mechanism, so you need to be careful not to drop or subject the watch to shocks. This model also does not have a shock-resistant mechanism.
The chronograph mechanism was also installed.
Vintage models have various problems, so they require adjustments as they are assembled and run tests.
Balance screw adjustment
The accuracy and beat error are adjusted while correcting the hairspring. Once the shape is taken, the regulator is set to the center and the balance seat (the weight attached to the balance screw) is added or subtracted to change the weight and adjust the accuracy. This is a very delicate process and may take some time depending on the individual piece. This is an adjustment that is only made during assembly, and is then adjusted while the watch is running. For this reason, it takes longer to adjust vintage models than usual.
Finished
Online Shop Bulova https://matsunotokeiten.myshopify.com/products/bulova-valjoux-23-60-60%E5%B9%B4%E4%BB%A3%E8%A3%BD-buljoux-23 ...
It is neither shock-resistant nor waterproof, but that is the fun and character of vintage watches. Please check out our online store.
Currently, the overhaul will be completed in late January next year. Thank you for your understanding. We will also list the details of the repair. We hope that it will be helpful.