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Old 12th Jun 2015, 10:38 am   #1261
Pmark34
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Default Re: AVO Multimeter survey

Hi.

first time posting on a forum so hope it works OK. I've been colecting AVOs for few years and have been reading other posts on here with great interest. Ive got about 10 AVOs a model 40 from Feb 1944 in a box with the shunts & voltage multiplier, 3 or 4 model 7s, an AVO test bridge meter (sadly not working damaged in the post) an DC AVO Minor, a universal AVO Minor (with box & leads), A number 1 high sensitivity meter, a Multiminor mk5 (in great condition with leeds case & instructions.

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.

Will try & put a full list of meters and serial numbers together and post it. Have attached some pics (hope it works).
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Old 15th Jun 2015, 7:22 pm   #1262
mark pirate
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Default Re: AVO Multimeter survey

I have just added another Avo to my collection, this is a model 9 mk4.
It is mint and boxed, complete with instruction book and accessories.
Serial No 2669-1V-170.

Mark
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Old 16th Jun 2015, 11:51 pm   #1263
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Default Re: AVO Multimeter survey

Just been given an 8 Mk:III by a former TV repairman who used it in his employ for a well-known but long-departed Workington TV dealer and repair business.

Serial No: 43288-666

A go-er and accurate, but needed balanced, and the pointer flies hard over -VE when Ohms or Ohms / 100 are selected at the same time as 50uA!
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Old 18th Jun 2015, 11:18 pm   #1264
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!

Phil
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Last edited by Phil G4SPZ; 18th Jun 2015 at 11:30 pm. Reason: Forgot attachment
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Old 18th Jun 2015, 11:28 pm   #1265
Phil G4SPZ
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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...

Phil
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Old 20th Jun 2015, 10:02 pm   #1266
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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   #1267
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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   #1268
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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   #1269
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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.
Joe
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Old 30th Jun 2015, 9:22 pm   #1270
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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.

regards
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Old 11th Jul 2015, 4:04 pm   #1271
pthomas
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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   #1272
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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   #1273
morrisvan
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Default Re: AVO Multimeter survey

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   #1274
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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   #1275
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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   #1276
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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   #1277
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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   #1278
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Default Re: AVO Multimeter survey

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   #1279
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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   #1280
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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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