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Sets, Parts and Service Information Wanted (private buyers only, no swaps) If you need help obtaining components, sets or equipment, post a message here. Private buyers only - no traders. No swaps.

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Old 21st May 2019, 10:40 am   #21
Pamphonica
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Default Re: 4PDT switch on-on-on format

Sorry if the description was misleading but unfortunately that is the standard way of describing such a switch.
It has to fit inside a small case so a larger substitute just won’t work.
As for the fault, the switch is switching very small currents, and I am getting intermittent operation on 2 of the 4 poles. Repeated operation did not clear the fault. I suspect some contact tarnish from prolonged storage, based on the badly corroded rechargeable batteries in it, although the switch is not corroded in any way.
Yes, I had spotted the Mouser part. It is the correct item, but unfortunately exceeds the purchase price of the whole unit by a factor of about 5x by the time vat and small-order postage is taken into account! I’ll go on looking for a more reasonable source, and perhaps dismantle the switch and attempt cleaning.
Thanks for all the inputs and glad to have got a few more grey-cells involved in the detective work.
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Old 21st May 2019, 1:01 pm   #22
Pamphonica
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Default Re: 4PDT switch on-on-on format

Problem(s) solved, for now at least...

I tried my best to force small quantities of DeOxit into the original swich, via the bush, and a small crack between metal bracket and plastic body, amd left it for half an hour, with regular operation of the switch.

I also remembered an old trick and re-installed the original switch, but upside-down, so a slightly different set of contacts were in play (one C/O set was not used before). It seems to work properly now, and after some fiddling around to remove the last traces of corrosion from the battery holders, which was producing odd results from high-resistance contacts, I now have a reliable voltage source, and the zeroing that was driving me crazy with the intermittent switch now works fine.

So that's it for now, although I think I will still keep an eye out for a replacement switch just in case.

The original equipment manufacturer replied that they could indeed supply a replacement switch, at 45 plus VAT plus carriage. Erm, no thanks, but a kind offer!

By the way, I dont NEED yet another precision voltage source (1uV to 1V DC) but for a few I couldn't resist. The model if you are interested is the Time Electronics 404N, which also gives a very nice potentiometer null function if you need to check high impedance standards like the Weston Cell.
The more recent version of this device (the Model 1007) costs approximately 200x what I paid for my device at Dunstable on Sunday.

Thanks all!
-Jeremy
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