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Home > Archive > Electronics repair > April 2005 > Old Avo 8
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| Ron(UK) 2005-04-16, 3:16 pm |
| Hi folks
I have an old but much loved AVO Model 8 which was my fathers before he
passed on. It has little monetary worth, but great sentimental value. We
both used this meter for years in our business.
Sometimes the needle only reads about half the deflection it should for
a given input, a tap on the case usually puts it right temporarily, but
I`ve spent hours searching for a dry joint or bad connection. Typically
the fault never occurs with the meter out of it`s case.
I wonder if anyone has experience of this problem? could it be the
movement itself? any clues?
Regards
Ron(UK)
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| Wayne Tiffany 2005-04-16, 3:16 pm |
| Could it be a static charge on the cover? I have seen this to be an issue
on some meters, especially if someone wipes dust off the surface.
WT
"Ron(UK)" <ron@lunevalleyaudio.com> wrote in message
news:d3du8o$cbm$1@hercules.btinternet.com...
quote:
> Hi folks
>
> I have an old but much loved AVO Model 8 which was my fathers before he
> passed on. It has little monetary worth, but great sentimental value. We
> both used this meter for years in our business.
>
> Sometimes the needle only reads about half the deflection it should for a
> given input, a tap on the case usually puts it right temporarily, but I`ve
> spent hours searching for a dry joint or bad connection. Typically the
> fault never occurs with the meter out of it`s case.
>
> I wonder if anyone has experience of this problem? could it be the
> movement itself? any clues?
>
> Regards
> Ron(UK)
| |
| Ron(UK) 2005-04-16, 3:16 pm |
| Wayne Tiffany wrote:
quote:
> Could it be a static charge on the cover? I have seen this to be an issue
> on some meters, especially if someone wipes dust off the surface.
>
> WT
>
> "Ron(UK)" <ron@lunevalleyaudio.com> wrote in message
> news:d3du8o$cbm$1@hercules.btinternet.com...
>
>
>
>
Yeah I have a Phillips analogue meter that does that a lot, rub the
plastic "lens" over the movement and the needle rises, to settle again
some time later.
My problem is definitely electro/mechanical in nature.
Cheers
Ron(UK)
| |
| Sam Goldwasser 2005-04-16, 3:16 pm |
| "Ron(UK)" <ron@lunevalleyaudio.com> writes:
quote:
> Wayne Tiffany wrote:
>
> Yeah I have a Phillips analogue meter that does that a lot, rub the
> plastic "lens" over the movement and the needle rises, to settle again
> some time later.
>
> My problem is definitely electro/mechanical in nature.
Is it in the meter movement itself? Sometimes, stuff flakes off of the
metal yoke and is attracted ib between the moving coil and the surrounding
piece to produce intermittent sticking.
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| |
| Ron(UK) 2005-04-16, 3:16 pm |
| Sam Goldwasser wrote:
quote:
> "Ron(UK)" <ron@lunevalleyaudio.com> writes:
quote:
>
>
> Is it in the meter movement itself? Sometimes, stuff flakes off of the
> metal yoke and is attracted ib between the moving coil and the surrounding
> piece to produce intermittent sticking.
>
I cant see anything, the needle doesn`t jam or stop suddenly. It`s as
tho there`s some kind of increased electrical resistance in movement
somewhere, and a gentle tap gets it right again for a while, I thought
maybe it was one of those common things that everyone knows about but me...
Ron
| |
| Adrian Brentnall 2005-04-16, 3:16 pm |
| Hi Ron
On Mon, 11 Apr 2005 14:43:12 +0000 (UTC), "Ron(UK)"
<ron@lunevalleyaudio.com> wrote:
quote:
>Sam Goldwasser wrote:
>
>I cant see anything, the needle doesn`t jam or stop suddenly. It`s as
>tho there`s some kind of increased electrical resistance in movement
>somewhere, and a gentle tap gets it right again for a while, I thought
>maybe it was one of those common things that everyone knows about but me...
>
>Ron
ISTR that some AVOs had a 'divide scale reading by 2' button - could
that be faulty / intermittent. Or maybe my memory's faulty ????!
Regards
Adrian
Suffolk UK
======return email munged=================
take out the papers and the trash to reply
| |
| Barry Lennox 2005-04-16, 3:16 pm |
| On Mon, 11 Apr 2005 13:32:08 +0000 (UTC), "Ron(UK)"
<ron@lunevalleyaudio.com> wrote:
quote:
>Hi folks
>
>I have an old but much loved AVO Model 8 which was my fathers before he
>passed on. It has little monetary worth, but great sentimental value. We
>both used this meter for years in our business.
>
>Sometimes the needle only reads about half the deflection it should for
>a given input, a tap on the case usually puts it right temporarily, but
>I`ve spent hours searching for a dry joint or bad connection. Typically
>the fault never occurs with the meter out of it`s case.
>
>I wonder if anyone has experience of this problem? could it be the
>movement itself? any clues?
>
>Regards
>Ron(UK)
We had hundreds of them in the Air Force, and that was a known fault,
not common, but not rare either. Fixed by movement replacement, and
that was the major reason for getting rid of them, the spares became
outrageously expensive, ie you could purchase a lower-end Fluke for
less than an AVO movement.
Barry Lennox
| |
|
|
"Ron(UK)" <ron@lunevalleyaudio.com> wrote in message
news:d3e0e4$qvr$1@sparta.btinternet.com...
quote:
> Yeah I have a Phillips analogue meter that does that a lot, rub the
> plastic "lens" over the movement and the needle rises, to settle again
> some time later.
>
> My problem is definitely electro/mechanical in nature.
You can eliminate that by wiping the glass with a cloth damped with water
with a little dishwashing liquid. However IME it's dust or dirt in the
magnet gap. You may need to find a good meter repairman.
--
N
| |
| Dave Plowman (News) 2005-04-16, 3:16 pm |
| In article <ffkl51hejgoa6slabi37ec6qj9tvbaov35@4ax.com>,
Barry Lennox <rianz.15.barryl@neverbox.com> wrote:
quote:
> We had hundreds of them in the Air Force, and that was a known fault,
> not common, but not rare either. Fixed by movement replacement, and
> that was the major reason for getting rid of them, the spares became
> outrageously expensive, ie you could purchase a lower-end Fluke for
> less than an AVO movement.
;-)
You can still buy a new Model 8 Avo. About 600 gbp.
--
*The beatings will continue until morale improves *
Dave Plowman dave@davenoise.co.uk London SW
To e-mail, change noise into sound.
| |
|
|
"Dave Plowman (News)" <dave@davenoise.co.uk> wrote in message
news:4d5a1f4152dave@davenoise.co.uk...
quote:
> In article <ffkl51hejgoa6slabi37ec6qj9tvbaov35@4ax.com>,
> Barry Lennox <rianz.15.barryl@neverbox.com> wrote:
>
> ;-)
>
> You can still buy a new Model 8 Avo. About 600 gbp.
Holy crap in a bucket! I still have a Salford 50 Super Selectest which is
much nicer looking but it's movement sticks too now. However you can buy
those used for about US $50.
--
N
| |
| James Sweet 2005-04-16, 3:16 pm |
|
"Ron(UK)" <ron@lunevalleyaudio.com> wrote in message
news:d3du8o$cbm$1@hercules.btinternet.com...
quote:
> Hi folks
>
> I have an old but much loved AVO Model 8 which was my fathers before he
> passed on. It has little monetary worth, but great sentimental value. We
> both used this meter for years in our business.
>
> Sometimes the needle only reads about half the deflection it should for
> a given input, a tap on the case usually puts it right temporarily, but
> I`ve spent hours searching for a dry joint or bad connection. Typically
> the fault never occurs with the meter out of it`s case.
>
> I wonder if anyone has experience of this problem? could it be the
> movement itself? any clues?
>
> Regards
> Ron(UK)
Try gently tapping each component with a stick while watching the meter, you
may have a resistor with an internal break or an invisibly cracked solder
joint, happens sometimes.
| |
| Bram Stolk 2005-04-16, 3:17 pm |
| If it ain't static, it could be just friction in its pivots, normally
tapping with a pencil on its glass shall free the needle. If you are sure
the problem is not in the meter movement it must be one of these
series/shunt resistors which is common to all meter ranges. Is your problem
persistent on all ranges and functions/Ohm/VDC/VAC/Amp ? Is your problem
independent from needle deflection ? e.g at full scale/half scale/quarter
scale ?
Is your meter still properly balanced, i.e. reading does not change when
meter is rotated or tilted ?
"Ron(UK)" <ron@lunevalleyaudio.com> schreef in bericht
news:d3du8o$cbm$1@hercules.btinternet.com...
quote:
> Hi folks
>
> I have an old but much loved AVO Model 8 which was my fathers before he
> passed on. It has little monetary worth, but great sentimental value. We
> both used this meter for years in our business.
>
> Sometimes the needle only reads about half the deflection it should for a
> given input, a tap on the case usually puts it right temporarily, but I`ve
> spent hours searching for a dry joint or bad connection. Typically the
> fault never occurs with the meter out of it`s case.
>
> I wonder if anyone has experience of this problem? could it be the
> movement itself? any clues?
>
> Regards
> Ron(UK)
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