Electric WW Trimmer for Bulova Quartz

[whizzer]

I would like to replace the trimmer on a couple of Bulova 242 series circuits but can see nothing on the existing trimmers to indicate value, make, model, etc.
The circuits run and the accuset function works but the circuits lose 20 + seconds a day. The trimmers show signs of very rough treatment (distorted screw slots) and were probably damaged by such.
Watches these circuits were in run within specs with another circuit so it's not the motor or mechanical parts.
How do I find the proper trimmers ?
Thanks for any guidance.

 

[Skutt50]

Do you know if it is a resistance or capacitor trimmer?

If it is a resistor type the resistance would be easy to measure on one of the working parts..... You do however need a multimeter.

 

[whizzer]

Since there is no continuity across the leads of a good one I assume it's a capacity trimmer.

 

[Skutt50]

If it is a capacitor it will be a bit more tricky to measure it but if you can find someone with a capacitor tester they should be able to help out!

I have an old (Japanese) multimeter from the 70-ies which measures capacitance (if I only could find a proper 10v battery......) so they do exist even if not just any multimeter will do the trick......

 

[flynwill]

You will have a hard time measuring the existing with any accuracy. These trimmers are typically in the 20-60 pF (that's pico-Farads) range. I don't know if you can get suitable trimmers from the electronics distributors like Digikey, but that's where I would probably start. Look for something that will mechanically fit and buy several different ranges and give them a try.

 

[dAz57]

these capacitors have ceramic plates, very light pressure is used when adjusting them, any heavy handed treatment will result in cracking the ceramic plate and making it useless.

 

[whizzer]

Thanks for the information.
What I learned in the Army Communication School in 1952 is a bit outdated.
The trimmers in question seem to be of different types. One has thicker plates that look ceramic and the other has copper plates. I'll have to remove a circuit from an assembled watch to see which should be correct.
When time permits I'll check with a local electronic repair company as a possible source.

 

[Electro]

If your losing 20+ seconds a day, unfortunately you have a more serious problem. The trimmer pots only adjust for -+8 seconds a day. You can download the service manual here http://www.phfactor.net/wtf/Bulova and Caravelle/242.pdf