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Old 16th Feb 2006, 10:09 pm   #1
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Default DAC90A Wavechange Switch indexing.

The Wave Change Switch of the DAC90A I'm currently working on has no indexing or endstops ie it moves freely, but does not click into place on either LW or MW.

On the inboard end of the shaft are two rather bent brass tabs with holes in them. Am I right in thinking that a ball bearing fits in the hole in one tab and the other tab applies spring pressure to the ball?
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Old 16th Feb 2006, 10:51 pm   #2
Sean Williams
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Default Re: DAC90A Wavechange Switch indexing.

Hi Graham,

Yep, it has lost its balls!

Probably a result of being turned while the balls were corroded/stuck to the track.

Need to cannibalise a suitable yaxley switch......

Simple fix anyway

Cheers
Sean
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Old 16th Feb 2006, 10:56 pm   #3
mickjjo
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Default Re: DAC90A Wavechange Switch indexing.

Hi Graham, It sounds like the ball bearing has fallen out, I had this happen once, while demonstrating a set I had repaired, I had to take the whole thing to bits again.... . If the switch is not too worn you may have to try to put a bit more tension in the spring, not easy due to poor access. A drop of grease on the ball and surrounding area helps. Good luck with it!

Regards, Mick.
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Old 18th Feb 2006, 9:14 pm   #4
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Default Re: DAC90A Wavechange Switch indexing.

I managed to dimantle the switch without damaging anything except my hands. The stiff "circlip" on the shaft is a pig to remove as I know from past experience when rebuilding Type AB switches. Doing it without removing the wiring from the switch is even harder.

The springy brass ball carriers were bent to bry, but I've tweaked them back into something like the right shape.

I have a couple of questions which perhaps someone with a working switch can answer:-

1. Do the ball carriers both sit on one side of the ball, or does the ball sit between them?

2. What is the corect shape for the ball carriers when viewed from the side ie when looking at the long thin edge? Should they be straight or is there a kink in the middle so that they resemble a letter "V" with unequal legs, the longer leg being nearest the ball?

Thanks
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Old 18th Feb 2006, 10:59 pm   #5
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Default Re: DAC90A Wavechange Switch indexing.

Hi Graham, Yes both spring blades sit on top of the ball. I've drawn a picture to give the general idea of the shape the springs should be, Hope it helps Good luck! .

Regards, Mick.
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Old 19th Feb 2006, 7:27 pm   #6
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Default Re: DAC90A Wavechange Switch indexing.

I have a related problem. The diameter of my hole is badly warn. As a consequence I have not been able to find a ball bearing that would either (a) not drop right through or (b) get in the way of things (because of selecting an over-sized on). Methinks that's a bit of a problem. I've tried pretty much all metric and imperial sizes - all to no avail. Mmmmmmm....

Best of luck with yours - I hope you haven't got the same problem.

Regards,


Andy
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Old 19th Feb 2006, 9:12 pm   #7
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Default Re: DAC90A Wavechange Switch indexing.

Job Done! A sketch is worth a thousand words. Thanks mickjjo.


Andy.

In the flat state the ball would easily drop through the holes in the brass tabs. When I bent them to the "V" shape shown in mickjjo's sketch the ball stayed in place. If the holes are really worn you could try soldering a thin bent brass washer to the lower tab. Tin both surfaces first and sweat them together.
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