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Old 18th Jun 2015, 11:18 pm   #1261
Phil G4SPZ
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Default Re: AVO Multimeter survey

Quote:
Originally Posted by Pmark34 View Post
My latest buy was a 13 range model no 2 which seems to work but the needle on it does not return properly. On looking inside, it looks like the hair spring is damaged. Meter no.3759. Would greatly value any help or info on the meter or how to fix the spring.
That's a nice early DC-only Avometer! See below extract from Avo's Servicing Information which describes how to untangle hairsprings. If the hairspring is actually broken rather than tangled, the situation becomes more difficult. Movements can be repaired, but only with great care, and using a bright light and magnifier. Good luck!

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Old 18th Jun 2015, 11:28 pm   #1262
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Default Re: AVO Multimeter survey

Model D, serial number D 2104-541. This is a real oddball, being a Model D but based on a Model 7 panel rather than the usual Model 40, and having a 1mA movement! I am just embarking on a detailed investigation. I can only assume that demand from the Air Ministry in 1941 was so great that Avo were forced to use whatever panels and movements were available. This instrument shows signs of previous repairs...

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Old 20th Jun 2015, 10:02 pm   #1263
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Default Re: AVO Multimeter survey

Thanks Phil for the extract from the Avo's Servicing Information, will give that a try. below is list of the Avos I have
1-DC Avometer 13 range, model 2. No. 3759 (some where between 1927 & 33 I think) as mentioned in last post.
2-Universal Avo Minor No. 61469-1143 not working, possible hair spring damage.
3-Universal Avometer Admiralty Pattern 48A, with box shunts & voltage multiplier No. 13810-244, Fully working & in good condition.
4-Avo Minor No. 81783-646 fully working with leads & instructions.
5-Universal Avo Minor No. 101817-347 fully working with leads & instructions.
6-Avo Test Bridge No. 6504-647 (damaged in post, needs new valve & has case damage)
7-Universal Avometer Model 7 No. 229-A1061F some ranges not working.
8-Universal Avometer Model 7 No. 7141-4862 some ranges not working.
9-No1 High Sensitivity No. 5358 169 fully working with leads & case
10-Universal Avometer Model 7 No. unknown, has had replacement movement fitted working.
11-Multiminor mk5 No. 37418 fully working with leads instructions & case.

I also have 6 or 7 Evershed & Vignoles meters does any one know if there is a thread for them. or any dating info for them.
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Old 20th Jun 2015, 11:19 pm   #1264
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Default Re: AVO Multimeter survey

There isn't a collective thread for Evershed & Vignoles instruments, but if you type Evershed into the search box above you will find several individual threads. You may start a new thread if you so wish.
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Old 29th Jun 2015, 6:00 pm   #1265
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Default Re: AVO Multimeter survey

Multiminor Mk 5 27048
Travelled all around the World and still does.
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Old 29th Jun 2015, 11:59 pm   #1266
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Default Re: AVO Multimeter survey

Everyday meter!! Model 8 MKII
Serial number 166161-C-1163.
Not the engraving on the left,
SMA ( Snowy Mountains Authority)
E&M ( Electrical and Mechanical division)
and their plant number 324096.
I would be lost without this!!.
I do have a multitude of others, including digital,
NOTHING beats the ease of the Avo.
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Old 30th Jun 2015, 9:22 pm   #1267
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Default Re: AVO Multimeter survey

hi all.

I have two avo's a model 7 mk 2 well used metal cased example serial xxx88-A-456 working but under reads a bit i paid £10 from a junk shop. and a model 8 mk 5 very good order,plastic case though only three ranges printed on the scale serial number xxx67 8V/5/77 i paid £15 from the same junk shop.

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Old 11th Jul 2015, 4:04 pm   #1268
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Default Re: AVO Multimeter survey

Russell WB,
I think the main switch contacts are misaligned. You could loosen the screw central screw on the offending switch a little and push the moving contact with a flat bladed screw driver to get better alignment with the fixed contacts. look carefully to see whether or not the rotor aligns with the static contacts at the detent positions other wise you get strange effects as you described. Plan B is to check the leaf spring contacts which is best done by careful comparison with a known good meter to see if they lift and close in the right way. Adjustment is then a matter of cocktail sticks and long nosed pliers. I have sucessfully restored a number of Avos but they require extreme attention to detail!
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Old 12th Jul 2015, 7:07 pm   #1269
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Default Re: AVO Multimeter survey

Pthomas,

I did that shortly after I wrote that post! Sorted it now. When I looked at the service manual it showed where to set the cams and one of mine was out slightly, so I loosened the screw on the 'd.c. switch' and pushed it round a tad's nadger until the contacts raised fully. It now works perfectly.
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Old 14th Jul 2015, 11:51 am   #1270
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Re Avo Survey

Hi

This is my first post and my Avo collection is as follows
Mod 7 ser no 7xx5 20488 needs new movement
Mod 7 ser no 7x6x 30063 good working order
Mod 7 Mk 11 ser no 8xxx2 A 1258 good working order small chip on one side where it's been removed from case.
Mod 7 Mk 11 ser no 6xxxx8 A 1256 good working order
Mod 40 Mk 11 ser no 1xx0 8 467 m needs new movement
Mod 8 Mk 11 1xxxx1 c 962 working order but reads low on dc voltage (ex mod)
Mod 8 Mk 5 no ser no works ok had to repair pcb in a couple of places
Mod 8 Mk 5 ser no 0xxxx3 8v good working order
All bought second hand.
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Old 20th Aug 2015, 9:16 pm   #1271
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Default Re: AVO Multimeter survey

Several more avos have come my way:

model 2 ser no 3474 no terminal version aluminium case
model 2 ser no 6540 black terminal version aluminium case
model 47A ser no 8067-342 bakelite case model 40 panel moulding
model 40 ser no 40185-642 aluminium case
model 8 see no 45836-c-456 bakelite case


DC AVOminor ser no 77760-146 3/6mA version
DC AVOminor ser no 48083-48
Universal AVOminor ser no U22080-95

I tam gradually working through them, the two earliest now work, I have yet to seriously look at the rest.
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Old 20th Aug 2015, 10:28 pm   #1272
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Default Re: AVO Multimeter survey

An interesting sub-collectin Richard, especially to have "come your way" -.you must be very attractive to Avometers.

Could you give some more information on the DC models please? Is 3474 Rochester Row or Douglas Street production and could you post pictures of them please? I suspect that the second one, with the black terminals, has been modified; if not it could be quite a rare one.

PMM
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Old 20th Aug 2015, 10:42 pm   #1273
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They are douglas street and came as part of a collection of instruments that someone had amassed over many years.
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Old 20th Aug 2015, 10:49 pm   #1274
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I had to make a new scale for one as the paint had cracked. There were two open circuit resistors which are now fixed but otherwise both meters function but I won't vouch for accuracy.
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Old 21st Aug 2015, 11:47 am   #1275
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The D.C Avometer with the black terminals is in fact a rare model 6 as defined by PMMUNRO
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Old 21st Aug 2015, 12:49 pm   #1276
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Richard,

As Michael has told you, your second DC Avometer is the 22-range version which is one of the rarest of all Avometers.

Your luck was certainly in when that one found you!

PMM
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Old 22nd Aug 2015, 9:25 am   #1277
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Thank you both for identifying it and letting me know that I need to look after it! The instruction plate on the back( if I had looked) confirms that there are 22 ranges available. When received it had a Siemens size S battery which took a great deal of effort to remove and the terminals were absent. I replaced the latter with 4BA screws with heads removed and two terminals from a defunct Cambridge instrument.

I guess this one must date from about 1936/?
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Old 29th Aug 2015, 9:52 pm   #1278
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I have now looked at these two that I mentioned in a posting a few days ago:

model 47A ser no 8067-342 in bakelite case with model 40 panel moulding
model 40 ser no 40185-642 in aluminium case

From the serial numbers it would seem that these two were made just a few months apart and inside they appear much the same except that the model 47A has resistor wound on glass and the other has pink hi stab ones instead.

Does this mean that only 185 model 40s were made in the first 6 months of 1942?

The 47A has a bakelite casing with a model 47A instruction plate a battery box for 1.5 and two 4.5 volt batteries. the front panel has two sets of 6BA threaded holes one of which looks as if it would have suited an aluminium case. Perhaps it is a marriage as the following site indicates (if I read it correctly) that model 40s were supplied to the Admiralty but the serial number should have letter S above the number which this one does not.

Ignore the first couple of pages, there are diagrams and nice description here:

http://www.rnmuseumradarandcommunica...tion%20six.pdf
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Old 1st Sep 2015, 10:13 pm   #1279
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I picked up an Avo Minor MK1 AM the other day, dates from May 1943.
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Old 1st Sep 2015, 10:20 pm   #1280
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Default Re: AVO Multimeter survey

Richard (Barnmead) - you have a PM.
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