Moving a trimmer switch

[digibloke]

Hey all. I'm in the process of refitting a dead pulsar module with a national semiconductor module and have run into problems. As with many other modules the NS has the trimmer switch on the back and it protrudes too much to fit into the case once attached to the Pulsar 3013 base.

What I'm wondering is

A) Can I remove the trimmer from the circuit altogether (the quartz doesn't need trimming as it's keeping good time).

B) If I do this would I have to bridge the gap and what with (a capacitor perhaps?)

C) If I very carefully take the trimmer from the NS and move it onto the Pulsar base without turning it will it bugger things up?

Any advice would be greatly appreciated. DB.

[T-bird]

Hi DB.

My suggestion is to retain the trimmer. It is factory adjusted to optimize the QC frequency, and removing it may alter the accuracy of the watch.

Your last option seems a very good way to go. Just remove it and relocate it on the Pulsar plastic sleeve. I've done this once with a QC, I've added a small section of wire to relocate it, it works flawlessly. Another option is to perforate the plastic sleeve and make room for the trimmer. It is brutal, but if it won't interfere with batteries or anything else it is a quick fix. Check CompuChron's post on his Pulsar (Viva Italia). I had no choice there, since Hughes modules have a press-on QC. I perforated the sleeve - ugly, but working.

Don't forget to post the results.

Al. :D

[retroleds]

A) Can I remove the trimmer from the circuit altogether (the quartz doesn't need trimming as it's keeping good time).

The trimmer is probably set to it's midpoint(like most when leaving the factory)...it actually IS trimming the crystal,marginally. So same advice as T-bird - try to fit it in there.

[digibloke]

Thanks for the suggestions. I'm going to try to move the trimmer to the side of the NSC module (like the refit on Peter W's "Magic Digitals" http://www.digitalwatches.de/). I can't just make a hole for it on the pulsar base as it would be sticking out about 1mm in the negative battery recess right under the contact (far from ideal eh?)

I had no choice there, since Hughes modules have a press-on QC. I perforated the sleeve - ugly, but working.

Those Hughes QCs are a pain - on the smaller modules they sit separate from the main board attached by 3 almost invisible wires. I once had one come apart on me whilst removing it from a "liberace-esque" Accurist and it took me three evenings to re-attach it (it came very close to being scornfully tossed into the shoebox of LED doom).