22nd Feb 2017, 3:49 pm | #1401 |
Nonode
Join Date: Aug 2010
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Re: AVO Multimeter survey
I've now a small collection of AVO EA113 multimeters:
494.1069 s/n 388 816.270 s/n 697 5.642.1175 s/n 5471 I started out wanting just one......
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4th Mar 2017, 10:01 pm | #1402 |
Dekatron
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Re: AVO Multimeter survey
I have been given a nice Model 8 Mk III which, for a change, is in full working order: serial number 10827-265.
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Phil Optimist [n]: One who is not in possession of the full facts |
11th Mar 2017, 1:18 pm | #1403 |
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Re: AVO Multimeter survey
...I was given an 8/III a few months ago with s/n 12777/365, which with reference to Phil's s/n indicates an impressive production rate..
The dials are a bit sloppy but it all works. I think the key to longevity is to resist the temptation to whizz the dials round to 12 o'clock every time you put it away- i now adjust the dials before use not after. Moving parts are a killer as always! |
16th Mar 2017, 1:24 pm | #1404 |
Pentode
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Re: AVO Multimeter survey
Do you mean the range selector knobs?
Mike |
16th Mar 2017, 6:38 pm | #1405 |
Dekatron
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Re: AVO Multimeter survey
Yep, range selectors. Usually when i take the back off one of the meters i see a small amount of grease on the rotary contacts and the cam rotors, but they inevitably do lose a bit of precision in their action with extended use. Have had one or two jam solid at a certain point, when the rotary spade clouts a certain fixed contact, instead of sliding between. Tweaking required, access permitting.
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1st May 2017, 1:27 pm | #1406 |
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Re: AVO Multimeter survey
My first EA113 has joined the collection, and has now been repaired and is working nicely. The only serial number I can find on it is stamped into the rear case, no. 1377.
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Phil Optimist [n]: One who is not in possession of the full facts |
7th May 2017, 8:18 pm | #1407 |
Retired Dormant Member
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Re: AVO Multimeter survey
Hi all,I have a few AVO's
Model 7 7740 4351 7545 22153 758 1616 37896 A1252 7mk11 58426 A855 73883 A 1157 89114 A 1061 Model8 mk11 572131 c 257 165162 c 1163 8mk111 4422 c 1064 8mk1V unable to find number 8mk5 0527048 8V Test set multi no1 high sensitivity 10397 1270 That is all. Pelham 18 |
20th May 2017, 12:32 pm | #1408 |
Octode
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Re: AVO Multimeter survey
Hi to everybody in the Forum,
My humble collection of AVO Meters consists of the following: Model 8 Mk II 48549.C.656 (Very Early MkII I think. Back Plate says Model 8 only.) Model 8 Mk V 02154 8V/4/79 (Actually an MMR 14C front Panel ex Post Office) Model 8 Mk VII 8060 1003 1193 (Bar Code Label, I assume this is the Serial No?) Model 9sx 6305-15-863 (Test Set MultiRange No1 High Sensitivity) Can anybody point me in the direction of a Service Manual for the 8 Mk VII ? I need to sort out a sticky Meter Movement. My favourite by far is my 9sx. What a difference in quality between it and the Model 8 Mk V onwards! Ian |
24th May 2017, 9:44 pm | #1409 |
Triode
Join Date: May 2017
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Re: AVO Multimeter survey
Hi
I wonder if this thread is still being followed? Anyway as long time lurker I thought I ought to join. My AVO is a Model 8 and it has serial 143233-C-762 Cheers Neil |
27th May 2017, 11:59 am | #1410 |
Retired Dormant Member
Join Date: May 2017
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Re: AVO Multimeter survey
Hello there,
If anyone is still interested. A new AVO addict here, (actually I've been a fan of AVOs for decades) I Recently obtained a Test Set No.1 serial number 4304-468. I also have: a Model 7 (Mk. I) No. 71047-A40672 a Model 8 Mk. II No. 82286-C-1158 a Model 8 Mk. III No. 17473-665 It has a blown resistor, which from perusing the forums, appears to be |
6th Jun 2017, 5:48 pm | #1411 |
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Re: AVO Multimeter survey
Yes chaps this thread is most definitely still current! It is an ongoing thing.
I encountered an odd Admiralty meter a little while ago, and am putting brief details of it here for reference. The scale plate is '47A' type, and the identity circle on the front is also 'Model 47A'. However, above the identity circle is painted a letter 'S', which has then been been overcoated with varnish or shellac, to protect it from erasure/abrasion. The instruction plate on the rear is a standard Model 40 item, and the meter has all the internal extras associated with a Model 40. Someone (forgotten who, but thankyou!) has provided the attached typed document which looks to me like an old Admiralty repair guide/summary dedicated to RN Avometers.. If you look at the bottom of the page marked as No.67 it transpires that some Model 40's were supplied to the admiralty as 47A lookalikes, but painted with 'S' to identify them. I may have been premature in calling these meters Model 47AS, as it seems they are just a 40 with a few cosmetic changes! I would be interested to know how many are extant, but i don't imagine they are very rare. Mine has had a very hard life and took some bringing back. It's identification number is 17543-1144R. |
7th Jun 2017, 4:16 pm | #1412 |
Octode
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Re: AVO Multimeter survey
Dave,
That is an very interesting article for a number of reasons. Thanks for posting it. It has the characteristics of having been written by someone who had a good understanding of electrical instruments but no access to either ACWEECO or Admiralty technical information. They quality of writing shows a good general education, very likely someone who had been educated to at least HNC level, so probably a senior NCO or junior officer. There are a number of terms which are technically sound but different to those used by the manufacturer; for example "Overload relay" instead of "Cut-out". The writer seems concerned to pass on the information to others who needed to repair Avometers and the assumption that these would be Admiralty issue meters is implied. My understanding is that ship's personnel would have been directed to return faulty instruments to an official repair depot, but this would not have been easy for a ship's company on the other side of the world in wartime. The article would have taken many long and patient hours of research and drawing. The drawings are to a very high standard suggesting that the author had drawing office training, also indicated by the standard of hand lettering in the titles. In fact the drawings are to a much higher standard than contemporary ACWEECO drawings. The typescript is a bit rough, possibly having been written on a well-worn typewriter and one with a ribbon which was past its best. That would probably rule out the services of an official typist, unless Admiralty standards were below normal at the time. Note 6 is about the matter we were discussing, the supply of an 'S' variant of the 47A. The statement about these having been supplied instead of standard 47As implies that the writer knew what was being supplied to the Admiralty, more likely for a dockyard NCO or officer than someone in a ship. However someone shore based would probably have had access to official manuals. I don't know what manuals were ever available for these meters but it's highly unlikely that any Admiralty contract would not have required user and service manuals to be provided. (The 1940s Navy equivalent of the Air Ministry "APs"). It would be very interesting to know the source of this article. If the writer had produced over sixty pages to a similar standard before getting to the 47As, he (I assume it was a "he" given the culture of the times) had quite a passion for technical writing and a lot of time to devote to it. We have to wonder where, and in what circumstances it was written. PMM |
7th Jun 2017, 11:59 pm | #1413 |
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Re: AVO Multimeter survey
The writer's description of the acceleration trip mechanism was also worthy of praise.
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Phil Optimist [n]: One who is not in possession of the full facts |
8th Jun 2017, 9:09 am | #1414 |
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Re: AVO Multimeter survey
Special thanks Dave,
The above posts have certainly livened up the thread and have proven exceedingly interesting. The author of the instructions shows truly admiral talent and it forms a worthwhile addition to factory information which I for one will retain on file. Particularly worthy is the layout of the circuitry. Trevor. |
8th Jun 2017, 10:47 am | #1415 | |
Heptode
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Re: AVO Multimeter survey
Quote:
James |
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8th Jun 2017, 6:40 pm | #1416 |
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Re: AVO Multimeter survey
Thanks chaps, just tracked where the pdf doc. came from, Richard A kindly supplied it when i queried this particular version of meter. He said that it dates from 1945, but i don't have any other info. at this time.
17543-1144R was the meter on which i learnt how to re-balance movements, as they were corroded away completely, leaving only a bit of white powder. There is an overheated voltage winding on the top board, which was overloaded to the point where the board itself has swelled up. (Yes, it stinks!) I do wonder if the smoke from this event precipitated inside the meter and caused the corrosion between the dissimilar metals involved. |
11th Jun 2017, 3:06 pm | #1417 |
Pentode
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Re: AVO Multimeter survey
http://www.rnmuseumradarandcommunica...tion%20six.pdf
This is where the piece about the model 47/40 came from, maybe there might be other interesting things to be found there?
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12th Jun 2017, 1:05 pm | #1418 |
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Re: AVO Multimeter survey
Another to add to the list.
Avo Model 8 Mk III # 49298.1066 Not Harold's or William's ! In goodish order but the divide by 100 Ohms range reads the same as the Ohms range and the corresponding adjuster does nothing. Any ideas? Sam. Last edited by Boater Sam; 12th Jun 2017 at 1:07 pm. Reason: Grocers apostrophes. |
12th Jun 2017, 3:06 pm | #1419 |
Dekatron
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Re: AVO Multimeter survey
Sam, in my experience that will be caused by one of the leaf switch contacts not making properly. Behind the AC switch there are cams and contacts, once pair closes only on the ohms/100 range and puts a shunt across the movement. I think the contacts are "h" & "j" on the circuit.
I clean these contacts with a bent pipe cleaner moistened with Servisol. Check also that the mechanical actuation pins are in the correct positions. Leaf switch contacts are responsible for a lot of faults on the Model 8.
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Phil Optimist [n]: One who is not in possession of the full facts Last edited by Phil G4SPZ; 12th Jun 2017 at 3:08 pm. Reason: Afterthought |
12th Jun 2017, 6:03 pm | #1420 |
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Re: AVO Multimeter survey
Thanks Phil, looks very probable, I noticed on the circuit that there is only one pair of contacts that change from Ohms to divide by 100 Ohms, that's another job for later in the year.
Sam. |