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Old 24th Apr 2022, 11:43 am   #2898
The Philpott
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Join Date: Aug 2016
Location: Colchester, Essex, UK.
Posts: 4,076
Default Re: AVO Multimeter survey

Post 2897:- Fair comment. The quiescent 'bleed' from the D cell to the VC1 box is only a few uA, meaning a matter of years for a healthy cell to be depleted...but as we know some alkalines (particularly Duracell) have a habit of premature leakage, and the electrolyte is much more venomous than that of a Zinc Chloride.

The VC1 is rated for 15v @ 90uA maximum, but in practice the high resistance range uses much less. It is sized for the Model 8/IV onwards i think, slightly overlength for an 8/III but can be inserted if the grub screws are removed from the output contacts. The composite copper/plastic sheet conductor for powering the VC1 is the weak point; when i get round to installing one i won't be using it...too fiddly.

I am now relying on BLR 121's restuffed with (five) Lithium Metal CR1025 and taped back together. (I covered the mod. elsewhere, the diameter is too small meaning they had to be put in a plastic tube first)
I quite like this particular mod. as once you've selected the spring/spacer/tube the procedure is repeatable so long as CR1025 is still an available size.

A quick health check is of course to set the Avo to it's resistance ranges and see what voltage is available across the terminals. (Not foolproof though)

Dave
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