Seiko 7548-7000 and an Horotec Flashtest
Been tinkering with this bit of kit for a little white and so I'll provide some info.
Here is a picture of the Flashtest.
https://i.imgur.com/NL4Yr05h.jpg
The toy has some nice features; the ability to detect an impulse and set rate, check the power consumption of the circuit and movement, check battery voltage and also check resistance of the coil.
I first started cleaning the movement up and I must say that the cleaning fluids are much more effective. The mainplate here looking nice and clean.
https://i.imgur.com/zRThJ33h.jpg
Swapped over after installing the crown setting mechanism and ready to install the centre wheel and bridge.
https://i.imgur.com/oiHvrfEh.jpg
Train wheels installed along with reset lever.
https://i.imgur.com/LyaHThGh.jpg
Bridge installed and so now is the time to check the coil.
https://i.imgur.com/iAEWy2ah.jpg
As you might be able to see from this image there was a sign that someone had slipped and hit the coil with a driver most likely and therfore I was worried the resistance would be impacted.
https://i.imgur.com/ZZ5eICMh.jpg
https://i.imgur.com/Pr4l767h.jpg
We would need to see a resistance that's between the min and max values as per the movement, which would be between 2 and 4 kilohms.
https://i.imgur.com/vuZuAMxh.jpg
A coil that shows damage would end up causing us issues in that power consumption would rise or the rate of the watch would be compromised. If the resistance is just under 2kilohms, it might be feasible to allow it to stay in the watch and adjust the rate accordingly, but the movement would consume more power than necessary leading to a shorter battery life. Of course if the coil's connectors had separated then we would see infinite resistance and the watch wouldn't run.
As can be seen from this picture we are right in the middle of spec for the coil's resistance at 2.91 kilohms.
https://i.imgur.com/eXMVEnph.jpg
The Flashtest is becoming a favourite!
Next up I'll install the circuit and switch over to get on with the calender side.
https://i.imgur.com/QYvkFOAh.jpg
https://i.imgur.com/esiYQE2h.jpg
Which, again, is looking spotless thanks to the new cleaners. They might be overkill if you can mix your own chemicals up, but I can tell new that I could not do without the L&R111, and the rinses seem to do an excellent job at... rinsing, but also drying quickly without leaving any residue.
Once the calender side is installed it was time to check the movement's power consumption. I haven't the results of the test with crown out, but they were in spec, and so with crown in and the movement's total power consumption to be measured what we want to see is a draw no higher than 2.4 microamps crown in, and 0.9 microamps with the crown out. The circuit is still being powered with crown out as the quartz oscillator is still running, meaning the movement quickly jumps into action as soon as the crown is pushed back to the 0 position, but it is significantly less consumption than when crown is in and the movement is ticking.
https://i.imgur.com/wI3T5RUh.jpg
With the negative contact held with rodico I could take a picture of the readout! :)
https://i.imgur.com/bFCgAPgh.jpg
https://i.imgur.com/3LB5BQjh.jpg
Great news! Next I want to install the dial and hands and get it ready to be cased up, I'd already cleaned and installed the crystal etc, but just a few snaps taken and I'll post those pictures below, but before that and whilst it's outside of the case I wanted to measure the rate and adjust accordingly. The stronger the pulse signal detected by the Flashtest the more accurate the rate displayed will be. A new battery was installed before installing the dial and hands and the battery was just checked quickly to show we are getting 1.5V out of it. It's a brand new battery, so I don't need to worry about how much life is left in it, aslong as it wasn't a dud straight away!
https://i.imgur.com/5OqbATlh.jpg
https://i.imgur.com/PIM0krjh.jpg
The Flashtest counts down from 60 seconds and then displays the results after a further 3 second wait.
https://i.imgur.com/HYPTwZPh.jpg
Pretty good! But I wanted to do a little better, bear in mind that these movements are affected by temperature, so what we might see here may not equate to a real world accuracy test, but let's at least see how much better it can be. Adjusting the trimmer on these is almost more delicate than a balance regulator!
https://i.imgur.com/EOY1Ceyh.jpg
Too far!
https://i.imgur.com/MGP6J8Dh.jpg
Pleased with that!
https://i.imgur.com/LsOmCACh.jpg
https://i.imgur.com/YLesDjvh.jpg
Chapter ring and gasket ring installed, you can see the lip on the inside edge the gasket sits against.
https://i.imgur.com/kv7cOh5h.jpg
Retaining ring pressed home.
https://i.imgur.com/3l8J0Fih.jpg
https://i.imgur.com/ALNBXPph.jpg
A lovely, and very accurate, 7548-7000!
I hope my understanding is accurate here, but if there are any electronics gurus that want to correct my understanding of say the coil and what happens with an out of spec measurement that would be very interesting.
Thanks, TZ!
