Taylor meter

[Riccampbell]

I have just been given a Taylor multi meter, it is a Windsor model 71. It has lived in his garden shed for a number of years and is in quite a pickle but fortunately the meter movement is in working order, although I have only tried it on low DC volts.

As usual there are a number of resistors of various types, some of these consisting of wire wound round a former. Here lies the problem, the damp has got in and corrosion has rotted some of these away.

Does anyone have a circuit diagram handy? It looks quite a nice bit of kit and the case, although damaged, is repairable. All contributions/advice gratefully received. Ric.

[Ed_Dinning]

Hi Ric, these were nice meters and on par with the AVO 8.
The main multiplier resistors will probably be black panclimatic types and probably have the value printed on them.
The wirewound types will either be low range multipliers or shunts for the current ranges. I have some resistance wire in small gauge sizes that you can have if yoyu wish to re-wind them. As long as you know the approx. value you can rewind and then calibrate against a known meter.

Ed

[Freya]

Hi Ric,

I have one of these testers in the museum collection, if you need anything measuring I should be able to help. Possibly the easiest way would be to take a picture of the inside of yours and mark which components you require measurements from.

[Riccampbell]

Thank you both for the prompt reply. I will attempt to post pictures in due course, although my I.T ineptness is legendary.

Is it in order to post my address on the site? I don't wish to fall foul of the rule book. Cheers, Ric.

[Freya]

Use the PM system for any personal
info

[AC/HL]

It's for your own protection against spam and other nasties prevalent in the wild.

[Riccampbell]

Here are a couple of pictures of the damaged resistances. I hope they are of some use.
Another thing I thought of is to measure the thickness of the damaged wire, count the turns and obtain suitable wire to wind a replacement, what are my chances of success?

[Freya]

Sadly there appear to be considerable differences between them, yours being much older. ( could you post a picture of the front of yours out of interest please)

Your idea is most likely the only option really, except you will have to remove the existing windings and ascertain their resistance, which could mean re joining at any breaks.

If it helps, the resistances from left to right on mine are:
450K
225K
60K
12K
DIODE
DIODE
BLANK
1.5 OHM WOUND
150 OHM
2.9K
BLANK
BLANK
BLANK
1 OHM WOUND
BLANK
64 OHM
14 OHM
1.4K

[Ed_Dinning]

Hi Ric, the higher value conventional type resistors may be OK, but check resistance is in tolerance against marked values if any.
The heavy resistance wire is likely to be OK. The finer stuff may be problematical, but if you mic its diameter I may have something close.
If you have a read up on multimeter theory you will see it is a pretty simple basic circuit and the values can be calculated from Ohms law. Using a second meter and a variable power supply they are easy to calibrate.
A resistance box can be used to set up the higher value multiplier resistors, the value read off and the nearest value found and soldered in.
For the low value shunts the wire tables are consulted and a suitable length of resistance wire found. Its length is adjusted until the meter reads correctly; the wire is then coiled up neatly onto its former.

Ed

[Riccampbell]

Sorry for the delay, here is the front of my Taylor meter, Thanks for the information, I will keep you posted. Cheers, Ric.

[Freya]

There is very slight external differences on the scale marking between them, other than that they are identical.
Have you made any further progress ?

[Riccampbell]

Sorry, I got side-tracked, I'm sure you know how it is. Anyway, I am now back on with the meter. There is a wide variety of resistance wire available on ebay, so I am pining my hopes on re-winding the various resistances, quite a fiddle to get to bits though, but very interesting, I will post progress. Cheers, Ric.

[Riccampbell]

My resistance wire turned up today, I bought two thicknesses, for experimental purposes. I had a think about it and came up with this; the wound resistances are on a former 50mm wide. If I remove a damaged section of wire and obtain its resistance at perhaps a 100 mm length I can easily work out the original value by counting the turns. If I now work out this value on my new resistance (Kanthal) wire all I need to do is insulate it with varnish and wind it round the former. I will need to take account of the current going through the resistances and use a suitable thickness.

As all the wound resistances are damaged in some way; some corroded through, some with the insulation flaking off, I can replace all of them using the above method. Also, have you any suggestions on restoring the markings on the selector? and does it pull off? I can't see anything else securing it. What do you think? I have a niggling feeling it can't be this easy!

Cheers, Ric.

[Freya]

I use ultra fine line paint pens, available in many colours. If it overfills the depressed lettering use a sharp blade carefully to remove the excess when dry. Polish any marks out.

[Riccampbell]

Just as I had it all worked out.............Unfortunately the resistance wire I obtained was not given to soldering, so plan B was to work out all the resistances as above and find a suitable website able to supply all the various resistors, I got 0.5w and 5% tolerance. I will now put it all back together and post if it works or not.

Cheers, Ric.

[Riccampbell]

A result! with all the new resistors in and the meter back together and cleaned up it works a treat, what a nice meter. Many thanks to all who left comments and advice.

Cheers, Ric.

[Freya]

Well done. A credit to you.