AVO Multimeter survey

[AndyGilham]

Hello forum members, I hope you are all keeping well during this crisis.

I have received a new meter, a Universal Avometer Model 5 (36-range). The serial number is 36-5108 (March 1936) and its in reasonable condition.
It looks to have never been opened, so I intend to leave it that way.
The dial markings needs re-painting and I need to 3D print some replacement terminals.
Not a bad buy, just £32 from Ebay (No-one else bid!!)

Andy

[The Philpott]

-You'll have to open it up if you want to tackle the flaking scale plate!.. I managed to stabilise one in similar condition with the acrylic lacquer from a (clear over base) stone chip touch-up. The whole meter was so battered that i opted for conservation rather than outsourcing a scan and reprint.

A couple of your flakes there have lifted to the point where they're angled away from the plate- so i think they will just snap off and fly away.

Dave

[AndyGilham]

Yes the flaking paint is a problem, but i am reluctant to open it. I had a go yesterday, and the rubber is perished and will become scrap. However, if I can get it, i’ll Give it a go. You just sprayed the lacquer straight over the top?
Andy

[The Philpott]

Touch up pen with it's own brush- i did consider spray, but settled for localised dabbing. It dried too quickly for comfort, but it might just have been 'cos it was old stock.

I think the main reason i didn't want to spray was it would have involved more dismantling, and i wasn't too sure how glossy the finish would end up.

Dave

[Superscope]

Hi Andy,

Is this Meter for your own collection, or for the Museam?

I would be tempted to at least Scan the Scaleplate Carefully for posterity,
Maybe even place a printed copy back inside when any work is finished for
the next Enthusiast in 50 years time who is trying to work out the serial Number and Date information
which for sure will have flaked off..

I have another Model 5 sitting on the “To Do Shelf” and this is what I plan to do.
The Scaleplate is complete, reasonably flat but clearly starting to delaminate, although not as bad as my last Model 5 restoration.
Like yours, the Scaleplate is worth saving rather than replacing with a Scan, an option I didn’t really have last time round.

Unfortunately the scale plate will probably continue to degrade even if it is temporarily stabilized.

The Model 5's seem particularly prone to this De-lamination disease!

Anyway, great to see the Thread spring back into life and I hope everybody is Ok in these Crazy Times.



Ian

[The Philpott]

The paint certainly didn't bond well to the plating they used- the same as on my Model 4. Problem solved later by having a cut-out in the scale plate and a separate mirror finished plate sitting behind.

For appearances sake (ie to conserve the look of a Model 4 or 5-which i believe are similar) A single scan might be printed several times..But to have a better chance of alignment/accuracy/coherence between the entire needle sweep and the scale markings, every scan would have to be based on the original article (if of course there is enough of it to work with!)

Dave

[AndyGilham]

Right now the instruments I have collected (yes this Model 5 is for the museum) are locked away in a windowless room. So I guess further deterioration is unlikely for now.
Any suggestion on opening the instrument, without causing too my much damage to the seal?

The site developments have been put on hold, due to the current situation, so could be some time before we back to normal. But Megger are a key company, so work continues in manufacturing new instrumentation

Andy

[The Philpott]

I have just had a new look at my lacquer bodge under x10 magnification. It still looks stable, but some tiny cracks are evident in the lacquer, which are not related to any cracks in the paint. Not an ideal 'repair', just a salvage operation really.

Edit: You mean the rubber seal round the case? If it wants to fall apart when you open the meter up, there's nothing you can do- the same thing happened to my vintage meter, and newer (used) spare i had to hand was too thick. I just shrugged, and reassembled it without a seal to avoid strain on the screws. My philosophy was that dust won't really get in as it's not subject to a harsh working environment any more.
Dave

[Superscope]

The Later Rubber Seals (From around the late 70's) seem to have been made from a type of Plastic rather than Rubber.
I think these might be slightly thicker than the original style Rubber ones and
don't give as much, so they could cause some problems I guess.

Not really had a problem fitting any Rubber ones (NOS or S/H), but I've only
had to do this if the Seal was missing in the first place.
Not had a Seal fail on me and need replacing yet! (oop's, maybe shouldn't have said that!)

I have also made my own using Nitrile Rubber Cord.
Indistinguishable from the Real Deal when fitted and very supple.

If you do have an issue Andy, I'm happy to make you a replacement.
I'm sure I have Cord left, just need to dig it out.
Assuming of course it is the Rubber Dust Seal you are talking about.

Ian

[Chrispy57]

Hi - this is my first post after having benefitted from the wisdom of several members regarding the repair of one of my Avo 7s, thanks to pmmunro and PhilG4SPZ in particular.

I am pleased to be able to add my two serial numbers to the database; Model 7, 7743-10387 and Model 7X 3006-A-267.

The latter meter had been owned by the Australian Navy and is a Panclimatic version, acquired with an Accessories Kit containing shunts and transformers for "Big Jobs", which were still wrapped in their original waxed brown paper! It only required the addition of a PP3 battery case and a wipe over.

The other Model 7 had several burned out resistors and also needed battery holders fitting and a good clean up - a very satisfying few hours pottering.

I have attached photos in case the Accessories are of any interest.

Cheers
Chris

[AndyGilham]

Two nice looking Avometers. Thank you for the images. I am loving the 7x set, looks to be in perfect condition. I get a feeling there are a lot of military base's with untouched Avometers that have been sat in their stores for years!
Andy

[The Philpott]

Spectacular! You could re-do the white legends on the early Model 7 with off-white enamel paint or a stick of clock-makers engraving wax (The former is preferable but you have to be careful to keep it out of the crackle finish type surface on the meter facia, it can be a pain to remove.

Dave

[Chrispy57]

Hi Andy,
yes, I'm sure you're right about the forgotten stockpile of test equipment, let's hope it continues to be released from time to time. I have an Avo CT160 valve tester and a CT446 transistor tester which each bear the name of a UK military base on their cases, so I guess the trickle has continued for a number of years.

I was a little dubious about the Avo 7X and accessories arriving safely from Australia a few years ago, but happily they did. I will never use the 100A shunt of course, but they are a pleasure to look at from time to time.

Cheers
Chris

[Chrispy57]

Hi Dave,
thanks for the further advice about the restoration of the legends, I had been doing a bit of research on this via previous post on this site - I seem to remember your name coming up during my reading.

I don't recall seeing the engraver's wax idea before, but a quick look on EBay shows that there are two types; hard and soft, the hard version requiring heat and therefore only suitable for metal surfaces. Would you recommend the soft type for this application?

I imagine the paint option would require a fine point, steady hand, magnifying glass and lots of patience!

Cheers
Chris

[The Philpott]

The paint option is easier than it sounds, especially on an early model.

Just need enamel paint and the appropriate thinners!

You don't have to be precise with the paint, the trick is to overdab then wait till it's almost dry- the excess can then be rubbed away with kitchen roll or a cotton rag- a small amount of thinners on the rag makes it easier. Phil suggested this method and it works well.

I'll get a photo of one i prepared earlier..

The engraving wax i bought was brilliant white and looked too new for my liking (it was intended for use cold, much like a wax crayon)

Dave

[The Philpott]

..Revell enamel ('Matt 5'- an off-white.)

It looked OK on this Model 7 but on meters where the scale-plate is a dull ivory/parchment/yellowed colour such as a Model D i spike it with tiny amounts of yellow and grey to dull it down for a good match.

(Revell's range of colours is disappointingly limited- to get 'RAF fuselage interior green' for model aircraft i had to mix it myself and record the formula)

As far as old Avo's go, if the bakelite has tiny chips or is very worn, micro bits of paint may stay in the material here and there- but i tolerate that. The switch pictured has such imperfections but the overall look of it is fine.

Dave

[Chrispy57]

Hi Dave,
thanks for your time and trouble in providing that guidance - the result looks great, I will try to emulate your quality of finish, fingers crossed. Looks like a quick order to EBay is on the cards then.

Cheers
Chris

[Superscope]

I very much hope everybody is doing well considering the current situation.

If your pulling your Hair out at Home out of Boredom, and you happen
to have access to your neglected Avo Collection, maybe you could help
to update the Survey a bit.

Great excuse to get those wonderful Meters off the shelf or out of the Cupboard.

7 Range (Model 1) Owners:

Anybody still reading this Thread lucky enough to have a Model 1?
Does this Model have a Data Plate on the back?
I think it does, but I have never seen one so can't be sure.
Assuming it does, is the Address on the back always Victoria Street?

I am assuming no Model 1's were built at Rochester Row, but would be interesting to know if any surviving Models have the RR address.


13 Range (Model 2) Owners:

If at all possible, could you let me know if your Model 2 has a Rochester Row or Douglas Street Address on it's Data Plate?
This Data was not recorded previously.
This will help narrow down the Manufacture Date of the Meters we know about since the Model 2 doesn't display a Date Code.

36 Range (Model 5) Owners:

There are two different versions of the 36 Range.
The early Meters had exposed Screw Heads on the P and R Controls.
The later ones had Bakelit Control Knobs.

I believe that probably at the same Time the orientation of the Horseshoe Magnet was changed.

So could anybody with a 36 Range let me know the P & R Control style and
should you have had the meter open, what is the Magnet orientation.

All the above assumes the Serial Numbers are already recorded in the Survey,
any new Numbers even more welcome.


On an aside, I noticed that the Model 4 and Model 5 may share the same
Serial Number sequense!



Ian

[Sinewave]

Will check my Model 5's.

[Pamphonica]

Model 1: (Original): s/n 144187. Mine has no sign of a data plate on the back. There is some glue residue inside the battery compartment so there may have been a label there.

Model 2: s/n 1730 Rochester Row. s/n 2080 Rochester Row. s/n 4448 Douglas St. s/n 6052 Douglas St. No info on magnets.

Model 5 s/n 6283 bakelite P&R knobs. s/n 6384 bakelite P&R knobs.

Please note that Model 2: s/n 6052 is a serial number correction. Incorrectly reported as 6062 before.

Hope this helps.
Jeremy