UK Vintage Radio Repair and Restoration Powered By Google Custom Search Vintage Radio and TV Service Data

Go Back   UK Vintage Radio Repair and Restoration Discussion Forum > Specific Vintage Equipment > Vintage Test Gear and Workshop Equipment

Notices

Vintage Test Gear and Workshop Equipment For discussions about vintage test gear and workshop equipment such as coil winders.

Reply
 
Thread Tools
Old 12th Jun 2011, 4:02 pm   #661
Paul Adams
Retired Dormant Member
 
Join Date: Apr 2011
Location: Wolverhampton, West Midlands, UK.
Posts: 253
Default Re: AVO Multimeter survey

Hello,

Thanks for that info, I took a look inside and couldn't see any 'glass cylinder'
only the high stability resistors, as shown in photo 2.

Another interesting thing that I noticed was the lack of the 'Q' potentiometer
that has a knob that seems to be part of the moulded front, as the rear of it lacks the variable resistor (photo 1).

I have now taken the wooden battery compartment out which needs cleaning, also I intend to repaint the aluminium case with spray hamerite, as during it's life someone has repainted it with grotty blackboard paint, only thing is what colour would it have been?

I have a couple of model 7's and they appear to be a silver hamerite finish.

Also and finally do you know as to where I can obtain a circiut diagram for the model 'D'

T.I.A

Paul.
Attached Thumbnails
Click image for larger version

Name:	Photo 1.jpg
Views:	267
Size:	104.0 KB
ID:	52349   Click image for larger version

Name:	Photo 2.jpg
Views:	288
Size:	106.5 KB
ID:	52350  
Paul Adams is offline   Reply With Quote
Old 13th Jun 2011, 8:30 pm   #662
new2brian
Retired Dormant Member
 
Join Date: Oct 2010
Location: Bradford, West Yorkshire, UK.
Posts: 4
Default Re: AVO Multimeter survey

Quote:
Originally Posted by Alistair D View Post
Andrew

I have a scrap 8 mk2 here. You are welcome to any of the battery box components for the cost of p&p. Let me know exactly what you need.

Al
Hi Alistair I have a 8 mk2 and missing metal cover over 1.5volt battery. Also the Battery case cover is missing. The meter works great though.
Any parts you can spare gratefully appreciated. new2brian
new2brian is offline   Reply With Quote
Old 13th Jun 2011, 9:13 pm   #663
Alistair D
Nonode
 
Alistair D's Avatar
 
Join Date: Jan 2010
Location: Edinburgh, UK.
Posts: 2,008
Default Re: AVO Multimeter survey

Hi there

Unfortunately the battery case cover was missing on the scrap one when I bought it.

Not quite sure what you mean by 'metal cover over 1.5volt battery'. Neither of the AVOs I own have any kind of cover over the 1.5volt battery. Do you mean the battery contact brackets?

Al
__________________
I won't tell you how I discovered that.
Alistair D is offline   Reply With Quote
Old 13th Jun 2011, 11:46 pm   #664
pmmunro
Octode
 
Join Date: Jul 2004
Location: Dundee, UK.
Posts: 1,793
Default Re: AVO Multimeter survey

Paul,

The high voltage multipliers in your Type 'D' are the four bobbins mounted on the bottom resistance board. This is the third variation, which I'm not sure if I've seen in a 'D' before.

The correct paint for an aluminium cased Avometer is crackle finish black. (e.g. http://www.frost.co.uk/automotive-pa...t-aerosol.html) I have successfully used aerosol paint for this in the past but it is temperature critical and needs a minimum of 22 deg. C to give the right effect and this is not a normal climatic temperature on any but a few days each year in this part of the world, (but then we don't have many floods, earthquakes or volcanic eruptions either). Some day the paint oven project will make it to the top of the list.

You should find Type 'D' circuit information which I drew some years ago within a previous thread on the forum. If not, send me a private message with an email address.

There is no 'Q' pot on the Type 'D'.

PMM
pmmunro is online now   Reply With Quote
Old 14th Jun 2011, 9:45 pm   #665
new2brian
Retired Dormant Member
 
Join Date: Oct 2010
Location: Bradford, West Yorkshire, UK.
Posts: 4
Default Re: AVO Multimeter survey

Quote:
Originally Posted by Alistair D View Post
Hi there

Unfortunately the battery case cover was missing on the scrap one when I bought it.

Not quite sure what you mean by 'metal cover over 1.5volt battery'. Neither of the AVOs I own have any kind of cover over the 1.5volt battery. Do you mean the battery contact brackets?

Al
Not the contact bracket but a flat metal sort off springy metal lipped at one end piece that stops the battery popping out of its contacts. It fits only on top of the U2 battery.
My other Avo 8 has one. I could post a photo! Brian
new2brian is offline   Reply With Quote
Old 14th Jun 2011, 10:00 pm   #666
Alistair D
Nonode
 
Alistair D's Avatar
 
Join Date: Jan 2010
Location: Edinburgh, UK.
Posts: 2,008
Default Re: AVO Multimeter survey

I remember seeing that. Both of my working AVOs have a foam pad glued to the underside of the battery case cover. It sound like the clip was dropped on the '8 mk3. Sorry. I cant help.

Al
__________________
I won't tell you how I discovered that.
Alistair D is offline   Reply With Quote
Old 14th Jun 2011, 10:45 pm   #667
new2brian
Retired Dormant Member
 
Join Date: Oct 2010
Location: Bradford, West Yorkshire, UK.
Posts: 4
Default Re: AVO Multimeter survey

Just had a look , yes your right Mk3 battery + terminal is different from my other Avo 8. The other one has a turned over lip at the top of + term and the metal cover clips over it and under top right of case.
My MK3 is missing the top case cover so of course didn't realise it had foam to hold battery partially in place.
Thanks for info . Brian.
new2brian is offline   Reply With Quote
Old 19th Jun 2011, 1:43 pm   #668
ENGLISH VICTOR
Hexode
 
Join Date: Feb 2008
Location: Sydney, Australia
Posts: 356
Default Re: AVO Multimeter survey

I posses one only Avo 8 serial number 45554-C-356 It is complete with leads and leather case and fully functional.
Victor.
ENGLISH VICTOR is offline   Reply With Quote
Old 19th Jun 2011, 7:37 pm   #669
Andrewausfa
Octode
 
Andrewausfa's Avatar
 
Join Date: Dec 2010
Location: St Ives, Cambridgeshire, UK.
Posts: 1,177
Default Re: AVO Multimeter survey

I've recently purchased two AVO 8 Mark IIs, both seem to have been well cared for, with leather cases and are in GWO though with temperamental Zero x 100 adjusters

1: 85473-C-159
2: 71118-C-258

Thanks to Alistair for his help with a battery compartment bits for Mark I

Andrew
__________________
Invisible airwaves crackle with life. Or they should do.
BVWS Member
Andrewausfa is offline   Reply With Quote
Old 22nd Jun 2011, 3:43 pm   #670
Paul Adams
Retired Dormant Member
 
Join Date: Apr 2011
Location: Wolverhampton, West Midlands, UK.
Posts: 253
Default Re: AVO Multimeter survey

Quote:
Originally Posted by pmmunro View Post
Paul,

The high voltage multipliers in your Type 'D' are the four bobbins mounted on the bottom resistance board. This is the third variation, which I'm not sure if I've seen in a 'D' before.

The correct paint for an aluminium cased Avometer is crackle finish black. (e.g. http://www.frost.co.uk/automotive-pa...t-aerosol.html) I have successfully used aerosol paint for this in the past but it is temperature critical and needs a minimum of 22 deg. C to give the right effect and this is not a normal climatic temperature on any but a few days each year in this part of the world, (but then we don't have many floods, earthquakes or volcanic eruptions either). Some day the paint oven project will make it to the top of the list.

You should find Type 'D' circuit information which I drew some years ago within a previous thread on the forum. If not, send me a private message with an email address.

There is no 'Q' pot on the Type 'D'.

PMM
Hi again,
Thanks for that info and yes i did find the circuit for the model 'D', I aquired another AVO, this time a model 47A the serial number is: 1137-99 (see pics) which is in a bit of a state i am afraid as some previous owner has at some time had the movement out, as the needle is bent, with wires off inside.

Does anyone have any suggestions where i can get a circuit for the 47A or what it comes close too, please.

TIA

Paul.
Attached Thumbnails
Click image for larger version

Name:	47A Front.JPG
Views:	218
Size:	195.2 KB
ID:	52829   Click image for larger version

Name:	47A Back.JPG
Views:	204
Size:	165.6 KB
ID:	52830   Click image for larger version

Name:	47A Scaleplate.JPG
Views:	204
Size:	189.3 KB
ID:	52831   Click image for larger version

Name:	Serial 47A.JPG
Views:	204
Size:	162.2 KB
ID:	52832  
Paul Adams is offline   Reply With Quote
Old 22nd Jun 2011, 9:09 pm   #671
pmmunro
Octode
 
Join Date: Jul 2004
Location: Dundee, UK.
Posts: 1,793
Default Re: AVO Multimeter survey

Paul,

The Admiralty PATTERN 47A is basically a Model in Naval uniform so if you have the circuit diagram for a Model 40, it will be very close.

The movement of your meter is certainly going to need some work if only to straighten the bent pointer which in turn calls for rebalancing of the movement.

At the very least you would be best to have the Model 40 service manual and depending on your experience other guidance too.

Let me know what you think you need.

PMM.
pmmunro is online now   Reply With Quote
Old 24th Jun 2011, 9:57 pm   #672
Paul Adams
Retired Dormant Member
 
Join Date: Apr 2011
Location: Wolverhampton, West Midlands, UK.
Posts: 253
Default Re: AVO Multimeter survey

Hello again,

I think i may have bitten off a bit more than i can chew with this one, as a closer inspection has revealed some of the resistors on the bakerlite strips have burnt out (the wirewound types wound around the bakerlite) plus i don't have any service info for it, i have looked on the internet for some info but not had any luck so far.

I have managed to repair all of my other AVO's previously but this one has to be the worst find yet !

I will probably have a good go at it on a 'rainy day' and there's plenty of those at the moment.

If you have any suggestions, i would be only too happy to hear them.

Best Wishes

Paul.

Last edited by Dave Moll; 24th Jun 2011 at 10:25 pm. Reason: unnecessary full quote of preceding post removed
Paul Adams is offline   Reply With Quote
Old 2nd Jul 2011, 5:48 pm   #673
Paul Adams
Retired Dormant Member
 
Join Date: Apr 2011
Location: Wolverhampton, West Midlands, UK.
Posts: 253
Default Re: AVO Multimeter survey

Another Serial Number for the collection, picked an AVO 8 mk3 from a local car boot today a bargain at 4 quid, anyway S/N: 68894 1267

What's more it all works.

Paul.
Paul Adams is offline   Reply With Quote
Old 7th Jul 2011, 12:19 pm   #674
noble kiwi
Pentode
 
Join Date: Jan 2011
Location: Auckland New Zealand
Posts: 175
Default Re: AVO Multimeter survey

I hope that I have not become addicted, but have just acquired still another Avometer, this one being rather unusual. Some details indicate that is surely part of a limited production run. It is ex New Zealand Government Railways and is heavily engraved NZR No. 212. Sadly the moving coil is open circuit.

This Avo appears to be based on the high resistance model, with modifications probably to order and has a front Panel intended for a Universal Avometer. A two colour dial face has hand done calibration figures and is marked, “Type HRM, No. 693 - 848, Part No. 10945-36.” The movement frame is metal punch stamped, “10 May 1961.”*

The rear mounted instruction panel, has a small section blanked out during manufacture and is headed, “Universal Avometer” together with the old title, “The Electrical Equipment Co. Ltd, Winder House, Douglas St, London.”

The dial face shows current scales for volts, 0 - 100 and 0 - 25, both in black numerals, then in red numerals, Volts AC 1 - 10. Two scales are provided for resistance. One in black reading 0 - 50K, anticlockwise, and another in red reading 0 - 50 ohms clockwise.

The left hand selector knob has the figures for two ohms ranges obliterated and a button marked press, replacing the potentiometer normally fitted in the panel, selects the low ohms range. The small right hand knob and pot. facilitates overall ohms zero adjustment.

The position normally occupied by the upper zero ohms adjustment potentiometer, has a small matching knob operating a rather make shift friction drive. This moves the meters mechanical zero adjust and the usual position for a screw has not been drilled out and is blank.
The right hand selector knob provides for DC volts, 0 - 2.5, 10, 25, 100, 250, 1000 and AC volts, 0 - 10, 25, 100, 250, 1000. Terminals are provided for 2,500 volts, AC and DC.

Terminals do not provide for plug connection and the test probes are fitted with spade connectors. The bakelite battery lid incorporates a means of retaining the probes, a feature not found on my other Avo’s which have a simple metal plate. The carrying case is of synthetic leather and similar to the one I have with a Model 8, Mk V.

I would certainly like to find out more about this particular Avometer and hope that knowledgeable members will find it of interest and worthy of comment.

Trevor.
noble kiwi is offline   Reply With Quote
Old 7th Jul 2011, 7:11 pm   #675
M6ESR Tony
Diode
 
Join Date: Dec 2009
Location: Swindon Wiltshire
Posts: 3
Default Re: AVO Multimeter survey

Here are three Avo 8 serial numbers :-
Avo 8 Mk3 s/no 70624-1167.(This one I have owned and used since 1968).
Avo 8 Mk2 s/no 164745-C-1063.
Avo 8 Mk2 s/no xxxxxx-C-1163. (s/no obliterated).
Avo Muliminor No 5 s/no 93788.
Hope this is of some use.
M6ESR Tony is offline   Reply With Quote
Old 7th Jul 2011, 8:53 pm   #676
pmmunro
Octode
 
Join Date: Jul 2004
Location: Dundee, UK.
Posts: 1,793
Default Re: AVO Multimeter survey

Tony, Paul,

Thanks for the information, it's all useful and I hope to collate it whenever I get time.

Trevor,

Your experience is similar to mine - HRM series Avometers do seem tom suffer from o/c moving coils. As I have said before, this may be why the acceleration cut-out feature was deleted in the Model 8 leaving just the end stop action, but this is speculation.

As your meter was made in 1948, it seems likely that the movement was changed in May 1951, exactly when the Model 8 was introduced.

It's also interesting that this meter was bought by NZ Railways. Would you think it was for the Signals & telecomms section?

PMM.
pmmunro is online now   Reply With Quote
Old 8th Jul 2011, 1:43 am   #677
noble kiwi
Pentode
 
Join Date: Jan 2011
Location: Auckland New Zealand
Posts: 175
Question Re: AVO Multimeter survey

PMM,

Thanks for the info to date. I have no way of discovering from what section of the railways the meter originated. As available current ranges are limited, my thoughts suggested signals, which would also involve telecommunications.

What exactly defines an HRM series Avo? If the movement was changed as appears likely, this means that the "HRM" notation and the figures I have quoted, do not in fact apply to the original instrument.

I remain confused regarding a high resistance model fitted with universal model front panel as well as other modifications. Details involved in construction certainly indicate some form of non standard production series. The plot thickens.

Trevor.
noble kiwi is offline   Reply With Quote
Old 13th Jul 2011, 12:56 pm   #678
kelvinmunson
Pentode
 
kelvinmunson's Avatar
 
Join Date: Jul 2010
Location: Scunthorpe, Lincolnshire, UK.
Posts: 159
Default Re: AVO Multimeter survey

Hi, I have an AVO 8 MK III Ser No 12152 365

Regards

Kelvin
kelvinmunson is offline   Reply With Quote
Old 13th Jul 2011, 11:15 pm   #679
pmmunro
Octode
 
Join Date: Jul 2004
Location: Dundee, UK.
Posts: 1,793
Default Re: AVO Multimeter survey

Trevor,

Several people have suggested that the High Resistance Avometer series is something of an anomaly. The general appearance is similar to contemporary Avometers yet intriguingly different, as are some of the features and the interior construction.

The HR series was produced at a time of inevitable change in the aftermath of the Second World War and was never widely advertised despite being the first mainstream model from this manufacturer to offer 20000 ohms per volt. (There was an Avominor variant at this sensitivity in the late 1930s but this was not made in large numbers judging by its extreme rarity).

I was told by an engineer who worked on Radar development during the Second World War that he made up his own 20000 ohm per volt voltmeter using a 50 microamp panel meter and that this was the usual practice at the time. This would suggest either that production of the existing designs took priority in the circumstances, or that "The Ministry" did not appreciate the need.

As I have said before the lack of HR series advertising could have been because the largest part of the production was already assigned to a Government customer, or for export, or materials may have been in short supply. It was however produced in at least three variants; the two basic versions which had different resistance ranges and a screened, panclimatic version.

It may be that ACWEECO were "feeling" their way towards the model which would be the most important instrument in their meter range, but it lasted only three years in production before being replaced by the Model 8. The Model 8 is very much in line with the general development of Avometers, or seems so in hindsight.

It is possible that the HR range was a sub-contract design or an adaptation of someone else's design made to look like an Avometer.
There was some, largely involuntary, "technology transfer" to the UK after the war. One well known example being the BSA Bantam motor cycle. If ACWEECO were one of the recipients - and there is no evidence that they were, this could just possibly be where the design came from.

The "Universal" legend appeared on all Avometers from the 20-range Universal Avometer of 1933 up to the Model 8 Mark IV which was replaced in 1972. "Universal" in this sense meant that the meter was equally suited to measuring alternating and direct values, just as a universal motor is designed to run on AC or DC supplies. It also probably suited ACWEECO's advertising which sought to imply that the meters were suitable for any kind of electrical work.

It was also around 1948, when the HR series entered production, that ACWEECO began to use the block magnet movement, rather than the earlier horseshoe magnet type. Although this was in line with advances in magnet technology, it is possible, in default of any evidence, that the new movement design was adopted from an outside source. This is pure speculation and may have no basis whatsoever. However, there is clear evidence that, much later, it was essentially a Taylor patented design that was the basis of the centre pole movement that was used in the Model 8 Marks V to 7 - over the last 37 years of Model 8 production. That's longer than the block magnet Model 8 movement (1951 to 1972 - in four versions), or the horseshoe movement (1927 -1947, discounting the earliest Avometer whose movement may have been supplied by Elliot Brothers).

I have to apologise for my emphasis on the importance of noting that some of the above comments are entirely speculative, but this forum is indexed by the world wide web and some of my previous comments, regarding the Type 'D' Avometer, some years ago, have appeared as facts and without acknowledgment on a personal web site.

I have studied all sources of Avometer information which I know to exist but I am always interested to hear of any new, verifiable sources.

PMM.
pmmunro is online now   Reply With Quote
Old 13th Jul 2011, 11:29 pm   #680
pmmunro
Octode
 
Join Date: Jul 2004
Location: Dundee, UK.
Posts: 1,793
Default Re: AVO Multimeter survey

Kelvin,

Thanks for contributing your Model 8 Mark III serial number.

This ties in with other numbers from the spring of 1965 and suggests that production was running at around 2000 Model 8s per month - along with other models.

The then new Dover plant had been in operation for around a year and production in London may have still been ongoing simultaneously.

At the time I had a Multiminor on order ready to be paid for by my paper-round money, but the delivery time was so long (at least three months) that I was glad to get the chance to buy an almost unused Model 8 Mark I instead. Avos were in great demand at the time.

PMM.
pmmunro is online now   Reply With Quote
Reply

Thread Tools



All times are GMT +1. The time now is 8:25 pm.


All information and advice on this forum is subject to the WARNING AND DISCLAIMER located at https://www.vintage-radio.net/rules.html.
Failure to heed this warning may result in death or serious injury to yourself and/or others.


Powered by vBulletin®
Copyright ©2000 - 2024, vBulletin Solutions, Inc.
Copyright ©2002 - 2023, Paul Stenning.