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Old 3rd Aug 2018, 11:20 pm   #1721
Sinewave
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Default Re: AVO Multimeter survey

November 2002 maybe?

My other later models, the last four digits are what appear to make the date up, so I wonder if that "1122" is November 2002?
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Old 7th Sep 2018, 8:51 am   #1722
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Default Re: AVO Multimeter survey

I picked up a very Late Model 7 Mk II recently in fabulous condition, like new.
Only defect is a missing Dust Cap on one of the PF Sockets.

Since there hasn't been a Serial Number given for a while, I thought I would take the opportunity of entering this one.

15687 7/10/76

What did grab my attention though, is that this Model 7 is about 4 Years later than
the Model 8's move to a Plastic Case and Strap, but it still has a Bakelite Case and Leather Strap.

It would seem AVO were still making very High Quality Meters well into the 70's.

Not sure when the last Model 7 rolled off the production line, we have a couple logged
from 1977 and a Model 40 logged as 1978.



Ian
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Old 7th Sep 2018, 4:14 pm   #1723
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Default Re: AVO Multimeter survey

Nice find! I think I have a 1970s Model 7 too.
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Old 8th Sep 2018, 9:20 pm   #1724
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Default Re: AVO Multimeter survey

Nice instruments the 7 mk2 is. I've got quite a few of them, dating between 50s to the 70s. What I do note is that some of the early 7 Mk2's with the later terminal types have a metal rear casing, then the bakelite made a return on the last models.
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Old 9th Sep 2018, 11:42 am   #1725
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Default Re: AVO Multimeter survey

...If the paint has started flaking and the aluminium box is in contact with the strap, the natural moisture content of the leather sets up deterioration in both materials. Shed and barn finds should be checked for this as the ally rots through and the leather goes super hard and brittle. A sudden loss of altitude and crash landing can ensue.

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Old 9th Sep 2018, 12:03 pm   #1726
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Default Re: AVO Multimeter survey

I wonder what's sparked off the latest trend in Avo Model 12's going for near £100?
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Old 9th Sep 2018, 11:10 pm   #1727
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Default Re: AVO Multimeter survey

When I saw the condition and late Production Date, I decided I had to have it.
Really is a stunning example, which is lucky as it didn't come in a case.

Anyway, this has encouraged me to get back into AVO's a bit and to pull my finger out and carry on with correlating the Multimeter Survey Data.

To that end, I have now completed the first part and attached it here.
Only includes Model 7's at the moment, no particular reason for that, it's just way it panned out.

I hope somebody out there will find this useful or Interesting.
It would be a real shame to let the Data obtained in this Thread go to waste.

I'm happy to maintain the Database if people still want to post their Serial Numbers.

Would be interesting also, to hear from anybody actually using this Data.


Regards

Ian
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File Type: pdf Multimeter Survey Report Issue 1.pdf (28.8 KB, 120 views)
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Old 25th Sep 2018, 12:24 pm   #1728
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Default Re: AVO Multimeter survey

I have just acquired a couple of AVOs
AVO 9 mkII seirial number on the scaleplate is: 9 II 1674-266
AVO 8mk IV 45359 84/5/71. The instruction plate on the back has:-
Meter multi Range 14C
PO AVO 71/3
Model 8 MkIV GPO.
The model 8 is in a leather GPO case.
Both in good condition but the Model 8 has suffered a battery leak, although it does not appear to have suffered any serious damage apart from white powder and corroded aluminium backplate.
I have another which I have had for 40 years is:-
AVO 9 mkII Serial number on the scaleplate is: 6374-866.
I shall be looking out for a set of leads and a case for the mk9
Don m5aky
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Old 25th Sep 2018, 10:41 pm   #1729
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Default Re: AVO Multimeter survey

Hi Don,

Thanks for the Serial Numbers. We haven't had many recently.

Any chance you could post some Photo's of the Mk IV ?
I assume this is the Grey/Green colour Case and
the Serial is on a Label on the Right side rather than printed on the Scaleplate?
A photo of the Front and Back would be interesting.


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Old 27th Sep 2018, 10:11 am   #1730
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Default Re: AVO Multimeter survey

That multirange 14/C sounds like it'll be a post office meter. The post office ones are nice to collect.
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Old 27th Sep 2018, 7:52 pm   #1731
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Default Re: AVO Multimeter survey

Don (vosperd) has said the Mk IV is a GPO meter.

I for one would be very interested in seeing some Photo's of a
Post Office 14C version of an AVO 8 Mk IV.

The MkV's seem fairly common, but I've not seen a Mk IV yet.



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Old 27th Sep 2018, 8:12 pm   #1732
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Default Re: AVO Multimeter survey

Ah so he did.

Yes the 8/V has plenty in Post Office guise. I've also managed to find an 8/6 in British Telecom dress.

I do have also a post office model 40 Mk1.

I know GPO 8/3's also exist but don't own one myself.
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Old 29th Sep 2018, 10:28 pm   #1733
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Default Re: AVO Multimeter survey

Avometer Model 4, serial 2152, date code missing.

Reaching the stage where i can actually say this beaten up meter is doing some of the things that it was designed to. Limited production, so i'm told, from Dec 1933 to June 1934. I think the fuse should be 4 ohms but if anyone can confirm it would be appreciated.

Tail balance weight very underweight (corroded away) solder used as coarse weight, then trimmed up using paint touch-up pen. Side weight increased also.
Bent needle straightened, spalling scale plate stabilised using the lacquer touch-up pen from a 'clear over base' pair of pens. Bakelite terminals missing, nothing available in the right size so over-bored the brass terminal to accept reasonably appropriate Belling-Lee Terminals in black, Slow Araldite used to stabilise. Discarded lower part of Belling Lee terminals, as limited amount of thread on back. Looks suitable.
Note the brass is horrible to drill, whatever pitch or speed is used. Copious amounts of chips and filings had to be cleaned away.

Large amounts of ferrous swarf jamming movement at 3 or 4 points. Removed with blu-tak on the end of a piece of solder- (less likely to cause damage than a cocktail stick, and more flexible.) Fuse head damaged, not fixed yet. Bodged in 4 ohms worth of resistance. Knocked the dents out of the back-box and adapted battery box for a D cell. Rotary selector fell into 2 pieces at this point, along a badly glued old fault line. Redone with Fast Araldite. Front facia legends redone with Humbrol enamel, mixed to an ivory colour.

Leaf switches cleaned and tweaked as not opening and closing properly.

The only remaining anomaly is the 1,200v AC and 1,200v DC ranges are behaving oddly, and i cannot find out why. The FSD varies between 250v to 600v from minute to minute, and often the needle wavers while a reading is being taken. Taking the shunt out of circuit it has a stable resistance reading, and the fault is starting to annoy me so i have left it alone for now.

My eyes hurt! But table-lampers didn't get the meter, so it's all good.

More pics follow

Dave
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Old 29th Sep 2018, 10:40 pm   #1734
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Default Re: AVO Multimeter survey

Avometer model 4

Pictures show lacquered scale plate, cork end stops for the needle, rear of the case, and the internals (minus the board holding the high voltage shunts)

The detents for the rotary switches are internal, which is a nicer design than later ones insofar as they do not get clagged up with dust and debris. Overall access isn't too bad, but one of the leaf switch stacks is very difficult to get at.
The P and R pots work surprisingly well. (R needed cleaning first)
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Old 29th Sep 2018, 11:07 pm   #1735
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Default Re: AVO Multimeter survey

Blimey, Dave, what a job! It has all the makings of a Success Story, though...

Does that model have the big fat wire-wound multiplier for the 1,200 volt ranges? It sounds like it might have become intermittent. Try subsituting a modern resistor temporarily and see if it stabilises.
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Old 29th Sep 2018, 11:47 pm   #1736
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Default Re: AVO Multimeter survey

Thanks Phil, yes it has a pile wound shunt on the bottom board, so large it is divided into two sections, a 123kohm section, linked to a smaller one of around 57kohm. I took them out of circuit to avoid reading errors and frustratingly they both show a stable resistance.

When you put them back into circuit, and monitor the overall resistance across the main terminals @ 1,200vDC setting, it sometimes fluctuates as low as 36k, as high as 198k, and anywhere inbetween.

I thought the same as you, and substituted a component resistor using croc. clip leads, but the fault remained. If i had simply soldered a wire wrongly when replacing the main terminals, i would have thought the fault would be stable...but it isn't. Maybe I will try soldering in a resistor just in case the fly lead was not connecting well enough.

Dave
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Old 30th Sep 2018, 7:20 am   #1737
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Default Re: AVO Multimeter survey

Weird! If 1,200 volts is the only range exhibiting this fault, and you've ruled out the multiplier by substitution, the only things left are the range switches or, more likely, a soldered joint in the common circuit leading to the big wire-wound multiplier or between its two sections.
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Old 30th Sep 2018, 10:43 am   #1738
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Thanks for the Serial Number Dave,

I was watching that one, and couldn't get any Number from the Photo's.

Yes, I am a Sad individual who logs any Serial Numbers visible on Ebay
Photos for the Survey. (Would be shame to waste a valuable source of Records)
I've managed to pull more than 70 Serial Numbers so far.

Your a Brave Man for sure taking that one on, but Hats of to you for
saving it. I have no doubt you will get to the bottom of your Intermittent High Z problem.
I take your point regarding Lamp Specialists! I cringed as well.

Did you notice that there were no less than Three Models 4's on Ebay
that week? Your one, One incorrectly described as a 1949 Meter and another
nice example.

Ian
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Old 30th Sep 2018, 11:12 am   #1739
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Default Re: AVO Multimeter survey

I haven't forgotten about the photos of the PO meter. Just not had a chance to get round to it. Will do so later today.
Don
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Old 30th Sep 2018, 11:18 am   #1740
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Default Re: AVO Multimeter survey

Hi Ian! The partial serial no. was repeated in pencil on the rear of the scale plate, on the magnet, and also on the rear of the facia, so i couldn't miss it.

I did notice there were a couple of oldies for sale simultaneously but i thought on inspection that the one with a £40 reserve was a Model 5..

Of importance to me was that Barnmead(Richard) should get some images for his archive.. as he has been waiting for a Model 4 for some time. Sorted!

I will probably leave the aluminium back-box unrestored, as any attempt is going to make it look like a dog's dinner. At least it's fit for purpose, ditto the wooden battery box, which is jointed differently from the later ones.

(Poking around for dry joints is hindered a little by the way that adjacent wires stick to each other due to the gooey nature of the insulation.)

Dave

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