AVO Multimeter survey

[Phil G4SPZ]

Ian, many thanks to you for all the dedicated effort and obvious passion you have devoted to this excellent piece of work. The descriptive notes are easy to read and very informative. The outcome is one of which SPCh would have been proud! Superb, well done and thanks again,

73 de Phil

[AndyGilham]

Fantastic work Ian..... really informative. And i’m Shocked I am top contributor.....! Looking forward to the next release. Still a lot of meters out there to be collected!
Andy

Originally Posted by Superscope

Wishing everybody on the Forum a very Merry Christmas
and a Happy New Year.

Please find attached the Multimeter Survey 4th Edition.

Special thanks to PMM for proof reading my Draft and offering a few comments
and corrections.

Hope you find this interesting and informative.
A lot has been added since the last Edition.

Once again, comments and suggestions, good or bad are welcome.


Ian

Thanks very much!!!

[mick-allen]

Hello,

My first post ...

My little AVO collection consists of (in order of acquisition)

Model 8 mk iv ser no: 67013 8X/4/72 (1972) my first AVO bought new with carrying case. I think I paid £45 for it.

Model 8 mk v ser no: 01562 8V/1/79 (2014 or 15) rescued from where I worked when they had a "clear-out" just before I retired. A lot of other stuff went as well - one of the guys in production had a signal generator and an oscilloscope! Came with carrying case, 2 test leads (both red!), 2 clips and one mk2 long reach clip.

Precision AVOmeter ser no: 273-566 (2016) My son paid half the price as a birthday present (thanks Chris!). The rubber covered leads are in a poor state (especially the red ones) so could well be the originals. Is there any way to repair them?

Model 8 mk ii ser no: 72426-C-358 (probably 2017) no test-leads or carrying case.

Model 8 mk iii ser no: 74616 268 (probably 2017) no carrying case. Test leads converted from modern ones (the shroud on the 4mm plug had been cut off. Got my son to get a case off eBay (it was printed with 'PLESSEY INST DIVISION BEESTON' and the AVO logo).

Model 7 mk ii ser no: 82723-A-1159 (June 2014) no test-leads or carrying case. I paid £15 for it from an 'emporium' only 1/4 mile from home! Got my son to get a case off eBay.

Model 9 mk ii ser no: 17406 369 (June 2018) (my son bought this for my 70th birthday but I had to collect it myself from a little village near Biggleswade!) Came with a set of AVO leads rubber plug on, two clips, one (black) probe & instruction book. Still had the factory seal but the mirror was loose (was held by what looked like masking tape) so I had to break the seal to get inside to do a repair.

Model 40 mk ii ser no: 27169-B-266 (Oct 2019) Came with carrying case, 3 croc clips and TWO SETS of AVO leads! (one pair rubber plug on and one pair PVC hook ended) but no probes.

Model 8 mk ? ser no: 52284-C-1056 (Oct 2019) This one was in a very poor state it looked like it had been used as a soldering iron stand. There were several 'blisters' in the top surface near the high voltage terminals and the 2500v DC- terminal cover was partly melted on one side. The 8k ohm resistor (between the 250uA & 50uA ranges was open circuit) as was the 980 ohm resistor for the 10v AC range and the 62 ohm resistor for the 2.5v AC range was too high (from a previous repair). These faults were corrected and it now works fine
The meter has 4mm sockets in the terminals but no 500v DC range so it looks like it's an early mk ii not a mk i that I thought it was. Damn! that means I will have to get a mk i for the collection!

Model 8 mk i ser no: 39937-C-1056 (Nov 2019) no test-leads or carrying case. Screw down terminals (so it's definitely a mk i). Factory seal still intact.

All the meters now work, and as far as I can tell, they're all accurate. All now have genuine AVO test leads but I need to get some more croc clips and mk2 long reach clips - the earlier long reach clips (for the mk i) don't seem to come up on their own.

Regards
Mick Allen

[Sinewave]

Welcome Mick. Nice collection there.

[The Philpott]

Hi Mick.
The rubber test leads (especially the red ones) are mostly rotten to some extent by now as you know- no way of repairing or consolidating! One annoying side effect is that they give off enough sulphurous fume over the years to blacken the silver switch contacts inside the AVO that they are boxed in with.
The Precision Avometers are beautifully made, the fact that they are huge bothers me not one iota, since they can be acquired quite cheaply.

The Avo 9 MkII has a trick that the 8 MkIII cannot do- it has a very low AC current range- i noticed this when i was playing with some neons.

I can't encourage collecting too much.. since it takes over the house, but an Avominor or two to keep in the car does no harm- and certain variants cope with being kept in such an environment better than a modern budget DMM!

Dave

[wpmills]

I have a Model 40 MkII. Serial number 02722. Dated 07/77.

I got this from a family friend who died. He worked for the New Zealand Electricity Department for many years. This particular meter was used in the testing and commissioning of the New Plymouth electrical power plant that has just recently been decommissioned and torn down.

It's in really good condition. The original box has some labels on it, and some writing from when it was being used, and the black lead has been soldered at one end.
The original leather straps are I tact and the plastic straps to hold the meter in place are still all good.

Pretty happy with it.

[The Philpott]

The later Model 40's are very neat and workmanlike inside, if it's anything like mine it has a zinc alloy cutout mechanism. I think in general that the alloy used must have been quite a good one as there is no trace of zinc pest. The 480vAC range should be quite accurate (but obviously only on a pure sine wave)

I don't think it's a good idea to toggle between the 1200vAC and 480vAC range when reading mains voltage on these meters. I have seen one or two that have arced.

Dave

[Adriaan01]

Hello,
'New in town' and happy to have read a lot of threads I liked very much.
And my contribution to the serial number hunt:
I own a AVO 8MK5 with serial 88593 8V/11/75, recently bought. Only AC voltages do not work properly ( about 15% too high. Anyone?).
Another 8MK5 has number 15469 8V/6/74, which I bought brand new during my work for 28 years at the Dutch importer of AVO/MEGGER/SULLIVAN and EVERSHED & VIGNOLES. Shoud be in order.
I also own a Model 15 with number 1179-V-1267. I think the 3 Amp range is bad.
The EA113 has number 2267 1170. Presumably some semiconductors are defective.
My free obtained AVO Precision first generation has number P 71 864. Wonderful and precise instrument!
On my workbench I have the last mentioned instrument and an 8MK5.
I also own an Dutch army version model CT160. And I am very glad with the free B184 LCR instrument.
Somewhere there is a zener diode tester and as portable model I use a Multiminor nest to a digital Fluke.
And today I bought an 8MK6, which has not yet arrived. Missing knob of the cutout. Anyone? Would like to have the service manual too of this model. Anyone?
When I have time to get hold of the VCM, I will inform you about the serial number.

Adriaan (NL)

[Adriaan01]

The AVO 8MKVI in on transport to me, and happily the seller took a photograph of the serial number. Yhere are to series of numbers, I publish them both:
1: 1233 M 91949 and
2. M008 VI 10/87
So, an early 8MK6.

[The Philpott]

Thankyou for contributing Adriaan, and it's nice to hear that another precision Avometer has been saved!

Dave

[Superscope]

Hi Adriaan,

At a guess, I would say the second Number probably reads
MOD8 VI 10/87

This would be the normal labelling on a Meter of this age.
But please let us know if it really does say M008 though.
Never pays to assume anything in this AVO meter Game


That's a pretty good start to 2020 with regards to Serial Numbers!
Wasn't expecting that to be honest.
Welcome to the Survey Forum everybody.

Especially good to see AVO's alive and well in NZ,
and that Model 40 MkII is the first one logged in the Survey from 1977.



Ian

[AndyGilham]

Another new instrument on the list for 2020.
Just received a donated Universal Avominor No.U104378-248 (February 1948)
It seems to have been through a modification, since there is an additional screw in the front panel, just above the 'AC Volts' marker. I will have a look inside when I get the chance.

Andy

[The Philpott]

Andy, it's very likely the additional screw at that location is an alternative fixing for the magnet, the original tapping into the bakelite wasn't very generous in depth- and sometimes got overtightened. The user then drilled all the way through and used a longer screw and nut!

Dave

[Adriaan01]

@ Superscope,
Do not have yet instrument in possession, underway to me from UK.
Surely you will be right with MOD in stead of MOO. I just read it fom a photograph in low resolution. After arrival will contct you again.
Meanwhile still hoping the instrument will be in good order, since I payed only 31 GBP (incl. transport!), much lower than similar models on Ebay….

After digging out my workshop I will pass the serial number of the CT160, which once belonged to the Dutch Army. It is in full working condition.
Maybe also the Zener Diode Tester will then show up....

[AndyGilham]

Dave,
You are correct, that does seem to be the case...… it aligns with the Magnet support.

Brittle Bakelite.... Its why I only design with luxury polymers like PC/ABS..... moulded to last and cheap as chips!

Andy

[The Philpott]

This example has been carefully tapped through to allow an over-length screw (of the same thread as original) to be used. Rather neat..but the screw used was steel!

Dave

[AndyGilham]

Just recieved a Model 40 for the collection.
Serial number 4486-541 (May 1941)
The instrument is moulded with the unique 'Model 40' motif panel and 'had' never been opened/serviced, until I took a look inside.
It's all original and in great condition.

Andy

[Barnmead]

I have five meters from the 70 series AVO/Taylor designs, three of which have serial numbers and two have defective movements.
Is there any interest in collating these in a future edition of the survey?
Is there any way of dating this from the serial numbers or the part numbers on the scale plates?

[AndyGilham]

I guess eventually the survey will include all the Avometers, so yeah it would be good for o include the 70 series. I would like the Model 12 added as well.
The 70 series instruments I have all include a year after the serial number I believe.

Andy