[volt-nuts] Junior Member Lost Shirt on 720a KVM Purchase

[Stan Katz]

Hi Dallas and Frank,

Dallas, the diameter of the switch you pointed me to is indeed too large.
It's only available at Digikey for a very affordable $92.00USD. The shaft
is also not compatible with the 720a construction.

Frank, I called up Fluke for a quote on the switch. Delivery in one week
for only $1060.00USD!!!! I'm still waiting for a quote from IET.  The ELNA
04 doesn't look like a candidate, but I have requested a quote anyway.

Shame on Fluke for using an outside supplier for that faulty switch. This
costly, and impractical to repair 720a has taken away all of the thrill of
classical analog metrology for me.

I think that I should consider a used Fluke 5440b and give up on lash ups
needing the 720a.

Stan



On Wed, Mar 25, 2015 at 11:37 AM, Dallas Smith <dosmith at outlook.com> wrote:

>
> Hi Stan,
>
> You might try this switch:
>
> Mouser: http://www.mouser.com/ProductDetail/NKK-Switches/
> PS4N-RO/?qs=%2fha2pyFadug%2fwBhWOsUs7NW51XexCQfYKxMRl5YO
> sfFFMCVUiewJdw%3d%3d <cid:part1.09050105.05060705 at outlook.com>
>
> It's a 30 amp (for low contact resistance) silver plated 12 positions,
> four decks. It may have a diameter that is too large. You will solder the
> wires to the switch, remove screws.
> I used it in my metrology switching center posted on:
>
> http://ko4bb.com/manuals/download.php?file=Fluke/Fluke_
> 720a_Switching_Center.zip
>
> Its is currently listed on mouser as Obsolete, I purchased these about two
> years ago.
>
> Dallas
>
>
>
> On 3/25/2015 7:38 AM, frank.stellmach at freenet.de wrote:
>
>> Hi Stan,
>>   The Deck A switch is a 3 layer, 1 to 12 type.
>>   I assume that one of the (ceramic?) layers is broken.
>>   You may desolder and disassemble the switch, to find out.
>>   Maybe it's repairable ( i doubt that).
>>   So you may get a spare part from Fluke, as I think, they still
>> manufacture these instruments.
>>   Or you may get such a switch from IET Labs, as they also actually
>> produce a clone of this.
>>   You may also order a custom made replacement from ELMA.
>> They offer a modular precision switch, gold plated contacts, Type 04
>> The isolation resistance is high enough, only the contact resistance is
>> not so well specified, and may degrade the performance of the 720A.
>>   http://www.elma.com/en-eu/products/rotary-switches/
>> rotary-switching-products/product-pages/type-04-detail/
>>   Frank
>>
>>
>> ---
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