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My new multimeter

(*steve*)

¡sǝpodᴉʇuɐ ǝɥʇ ɹɐǝɥd
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Jan 21, 2010
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Hi everyone, I just got myself a new multimeter!

IMG_20200302_175211_compress33.jpg

Isn't it a beauty!

When I got it, the needle was sticking a little, so I took the cover off and "adjusted" it. It appears the needle was actually bent, so a little, careful, tweak was all it needed to be as good as new.

It's an Aussie made piece of equipment!

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This unit is almost 100% bakelite construction, and is without any breaks or modes replacements.

The rear looks like this:

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It's hard to see, but there's something scratched into the bakelite.

A C Wilsher
Blomfield Av
Bega 7C
NSW

And inside, in ink in the bakelite (just as hard to read) is:

F C Wilsher
Bega

So... I got hold of the person I bought it from and asked if that name rang any bells. I got this response:

Oh wow, you have made us so happy. My Grandfather was an engineer and worked most of his life at the Bega County Council. Whilst we recall visiting him in his big office there when we visited on school holidays we found an old photograph of him climbing an electricity pole the other day.

We are more than happy to share information and have you share it in any forms.

His name was Frank Charmbury Wilsher. Frank and our beautiful grandmother; Dorothy, left Bega around 1980 to retire on the NSW Central Coast. They had been heavily involved in the art society and Masonic Lodge.

It's great to have some history about these pieces of equipment. It makes an item such as this just that but more special.

Back to the repairs... I noticed that the voltage range seemed ok, but the ohms range was very touchy, with the adjust pot being quite intermittent, and the needle unable to be set to 0.

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Here are the innards. The owners name is ink on the tag strip. Under it are the switches and pot.

Do I see a battery there?

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How old is it? How much has it leaked?

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Removing a couple of screws reveals the D cell. Can't see any leakage

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Well there's the reason! It has a miracle seal! So how old is that battery? Radio shack (trading as Tandy in Australia) opened in 1973, was acquired by another company in 2001 and finally closed in 2011. The battery is at least 10 years old, but I suspect it's much older. So while it's not really old, it's not new either!

I'm going to replace it with this

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Dick Smith was an Australian Company that was also bought by the same company and run into the ground. As they went out of business I purchased a number of these very good cells for almost nothing (under $US1 each).

So let's uncover that pot. First we remove the tag strip revealing some interesting resistors

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Anyone want to guess at the age of this meter?

Under it is the pot, partially obscured by a resistor of some sort (I think)

IMG_20200302_180022_compress72.jpg

And there it is. Can anyone tell me the value of that pot? And why?

Anyway, a replacement was sourced and fitted

IMG_20200302_181640_compress78.jpg

Note the difference in size. I hope there isn't a problem with power dissipation.

IMG_20200302_182042_compress8.jpg

Fits nicely, but it's upsidedown

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Old, and...

IIMG_20200302_181939_compress46.jpg

New. Pity it's not brass, but nobody will see it.

Ok, now, in the ohms range with the input shorted and the control all the way to the left:

IMG_20200302_182634_compress85.jpg

And all the way to the right. The intermittent problem is gone!

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But nowhere near zero :-(

However in the x3000 range with an external 45V power supply, the meter zeros.

I'm thinking that it's either very sensitive to voltage or some of the resistors have gone high. I'll have to get a non-rechargeable D cell to check that out.

While I had the 45V power supply (5 x 9V batteries) I compared the meter to one of my digital meters. It seems pretty close on the 50V range.

IMG_20200302_183442_compress32.jpg

And on the 10V range (with a single 9V battery) it's also close.

IMG_20200302_183531_compress7.jpg

So there's a bit more to do, but getting it going shouldn't be a huge problem.

I need to check the current ranges and the AC voltage ranges. But not today.
 

(*steve*)

¡sǝpodᴉʇuɐ ǝɥʇ ɹɐǝɥd
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And I've given it a bit of a clean. Mostly wiping of some dust and grime. It looks a bit better.

IMG_20200302_211659_compress8.jpg
 

BobK

Jan 5, 2010
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I hope you have a good supply of 45V batteries for those high resistance readings!

Bob
 
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