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 Post subject: Warped Scale on Simpson Model 9 DC Multimeter.
PostPosted: Mar Sun 20, 2016 6:46 pm 
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Joined: Sep Thu 23, 2010 6:37 am
Posts: 9423
Location: Powell River BC Canada
The fiber scale on my Simpson Model 9 has warped to the extent that is
causes a rub and stiction at a certain point on the scale.

This meter was bought on E-Bay, because I have a few other Simpsons
of that ilk with various ranges.

It is otherwise in mint condition, and I am sure the seller broke the seal
on the corner bolt to look inside. Shipping by mail might have involved
extreme STP conditions.

Will the scale un warp, if I put it in a warmed box for a period of time?
What is the scale fiber made of? Did it absorb water?

I could remove the scale/mirror plate and try to re glue the scale down.

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 Post subject: Re: Warped Scale on Simpson Model 9 DC Multimeter.
PostPosted: Mar Mon 21, 2016 1:11 am 
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Joined: May Sat 25, 2013 11:15 pm
Posts: 1423
Location: Central Iowa, USA
It will not unwarp. Consider contact cement to re-attach it. It will hold down a warp, but you only get one shot at getting it on straight.


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 Post subject: Re: Warped Scale on Simpson Model 9 DC Multimeter.
PostPosted: Mar Mon 21, 2016 2:16 am 
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Joined: Sep Thu 23, 2010 6:37 am
Posts: 9423
Location: Powell River BC Canada
too-bamp wrote:
It will not unwarp. Consider contact cement to re-attach it. It will hold down a warp, but you only get one shot at getting it on straight.


I'll remember that, when (if) , I take the meter out of the display case . :D

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 Post subject: Re: Warped Scale on Simpson Model 9 DC Multimeter.
PostPosted: Mar Mon 21, 2016 1:21 pm 
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Joined: May Sat 25, 2013 11:15 pm
Posts: 1423
Location: Central Iowa, USA
Hint: Put wax paper between the two, dried-until-tacky- cement coated surfaces, and slide the wax paper out enough to start one edge straight with light pressure, and once straight, slide the waxed paper out as you work the meter face down.

Can we get a picture of the meter? If it's worthy of a display case it would be a treat to see it.


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 Post subject: Re: Warped Scale on Simpson Model 9 DC Multimeter.
PostPosted: Mar Mon 21, 2016 2:08 pm 
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Joined: Sep Thu 23, 2010 6:37 am
Posts: 9423
Location: Powell River BC Canada
Model 9 is a generic form. There are many ranges available in this model group .

This particular meter has a sensitivity of precisely 1000 ohms per volt.
It would be very useful in verifying voltages on an old radio chassis that
used that kind of meter.

I wonder if the meter was made at 1000 ohms per volt, to fulfill roles in
calibration, set long ago?



Photo not too good.
Views of warps.

Attachment:
SIMPSON MODEL 9 WITH SCALE WARP VISIBLE ON RIGHT HAND  SIDE.jpg
SIMPSON MODEL 9 WITH SCALE WARP VISIBLE ON RIGHT HAND SIDE.jpg [ 75.98 KiB | Viewed 733 times ]


Attachments:
Simpson Model 9  15-150-300 VOLTS DC.jpg
Simpson Model 9 15-150-300 VOLTS DC.jpg [ 73.63 KiB | Viewed 733 times ]
Simpson Model 9 scale warp reflected in mirror.jpg
Simpson Model 9 scale warp reflected in mirror.jpg [ 64.39 KiB | Viewed 733 times ]

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 Post subject: Re: Warped Scale on Simpson Model 9 DC Multimeter.
PostPosted: Mar Fri 25, 2016 12:15 am 
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Joined: May Sat 25, 2013 11:15 pm
Posts: 1423
Location: Central Iowa, USA
That's cool old unit!
Thank for the pictures!


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 Post subject: Re: Warped Scale on Simpson Model 9 DC Multimeter.
PostPosted: Mar Sat 26, 2016 5:56 pm 
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Joined: Sep Thu 23, 2010 6:37 am
Posts: 9423
Location: Powell River BC Canada
I placed the meter across from a small portable fan heater operating
at about 600 watts with the limit set to 27 degrees C. After
about 9 hours of heat the scale warp reduced to where the pointer
did not stick.

The scale is not perfectly flat. The gluing is tight in certain places. But to
fix it properly, it would have to pulled off and the old glue scraped away.

Perhaps some old bits of that scale material could be looked at under
a microscope to find out what is the nature of the fiber.

I'm convinced it did suck up water. Some fiber sheets we used years ago
as solder shields on power switches, had to dipped in wax to make them
non hygroscopic to satisfy the approval agency the device was tested by.

Bach Simpson Canada manufacturing material spec sheets are not to
easy to find.

_________________
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VE7ASO VE7ZSO
Amateur Radio Literacy Club. May we help you read better.
Steve Dow
ve7aso@rac.ca


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 Post subject: Re: Warped Scale on Simpson Model 9 DC Multimeter.
PostPosted: Mar Sun 27, 2016 2:51 pm 
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Joined: Mar Wed 16, 2011 10:44 pm
Posts: 559
Location: Peekskill, NY
Good guess on moisture absorption.

You might consider including a small sealed silica gel unit inside the meter to
help dry out it out, long term.

Possibly this meter was stored in the past, in a damp area.


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 Post subject: Re: Warped Scale on Simpson Model 9 DC Multimeter.
PostPosted: Dec Fri 01, 2017 7:11 am 
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Joined: Dec Fri 01, 2017 5:35 am
Posts: 1
I have a model 9 ammeter, 2.5, 10 and 25A ranges. The scale label is wrinkly, the upper arc stops the needle at 20%, two further wrinkles are at 50%, lower arc, and 85%, upper arc. I'll try to bake out moisture. If the wrinkles reduce, a clothes iron or photo dry-mount press might make the glue reside sticky enough to hold... Meanwhile, a photocopy on heavy stock, with a plausible backing, will work as a substitute.

Bill


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 Post subject: Re: Warped Scale on Simpson Model 9 DC Multimeter.
PostPosted: Dec Sun 03, 2017 10:12 am 
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Joined: Sep Thu 23, 2010 6:37 am
Posts: 9423
Location: Powell River BC Canada
If you bake the meter, you bake every thing in it. Who knew when the meter was
made, with all the wonderful new insulators of the era, what they would do in 70 years ?

_________________
de
VE7ASO VE7ZSO
Amateur Radio Literacy Club. May we help you read better.
Steve Dow
ve7aso@rac.ca


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