Vintage u4313 multimeter

[Dred007]

Hello,

I inherited my grandfather's multimeter.
It's a u4313 made in USSR, a beauty. He would have had it at the shipyard everyday with him. From what I understand it has been up in the house attic for 20 years. Amazingly the original Russian made dry battery (4.5v) holds a charge of 4.3v I tested it with a modern multimeter. How is that possible ?

So I'm not sure I am allowed to ask for help but here is what is happening when I test the vintage multimeter with a 9v battery. I turn the dial to 1.5v the hand on the scale goes right over, I turn the dial to 3v same, I turn the dial to 7 same but when I turn it to 15v nothing happens. In my world, it should go a little more than half way. There is also a nob which is the zeroing scale. So it says to put the dial to 600v (max measuring possible of the multimeter) or 1500 amps (also the max amps it can measure) and zero it in. Unfortunately the zeroing in does not work. Nothing happens when I turn the potentiometer (0 nob). I tested the potentiometer with a modern multimeter and it has resistance.

Anyway on the back of the vintage multimeter it says that if you cannot zero the hand of the scale when putting the dial to k omhs then the internal power unit must be replaced.
What I was hoping for was that a person here in the forum with some insight would be able to educate me and help me to get a little further than what I have been able to do on my own. I respect that this should be sent to a professional to be fixed but I would really like to give it a shot myself before sending it in some parcel where I am not sure it'll ever make it or get broken even more. It's the only thing I have of my grandfather and I loved him very much.

Thank you very much for taking the time to read this and I hope you are able to understand what I wrote, kind regards, Peter Knox.

[Dred007]

Here are some pictures of the multimeter

****************/heZtvd
****************/ijbTTy
****************/bExrgJ
****************/gONfad

[Paul_RK]

Hello and welcome Peter,

I don't know the U4313, but from available photos it looks to be a not too distant relative of my U4341. To start the conversation by answering a few points:

It's not that unusual for a dry battery still to show something close to its original voltage after a decade or two when measured with a sensitive meter. Always, though, the internal resistance of the battery will have risen, so the voltage will fall heavily if much current is taken, and it generally won't be able usefully to power a radio, say, never mind a higher current item such as a torch.

When measuring a voltage, it's always better to start on a range higher than what you think the voltage will be - a 9 volt battery connected to the meter on its 1.5 volt range brings a real risk of damaging the meter movement. Best, then, to leave ranges below 15V well alone until you've a lower voltage to test them with. But at least you know they're responding, and for some reason the 15 volt range isn't... possibly a switch contact issue, more likely I would think to be an internal resistor gone open circuit, but I expect someone here with experience of faulty multimeters will have a better guess than mine.

I'm a bit puzzled by your references to zeroing the meter. There is a small adjustment screw just below the meter movement, which zeros the movement itself - turning this should let you set the meter needle to read zero volts / amps when at rest, with nothing connected to the test leads.

The zeroing knob is for the resistance ranges, and is used to set the needle to the zero of those ranges, on the right hand side of the scale, when the two test leads are connected (shorted) together. To do this the internal power unit (the dry battery) needs to supply something fairly close to its nominal 4.5 volts. Replacement batteries are still available, but I don't know how their availability in Denmark will compare to what it is here - the type used was more popular in various other European countries than it ever was in the UK. The modern type number is 3LR12.

Paul

[karesz*]

Hello Dred,
You can have schematics form here...
These multimeter has so called Isostat (or similar product), the 3 press buttom switches, they have often contact problems; apply please some contact spray for cleaning hes contacts, maybe the range switch need that too, than otherwiese (as I know) there are very robust instruments...
rgds, Karl

[Dred007]

Thank you to both of you for replying so quickly with great insight into my multimeter.

For Paul, I will definitely take advantage of the good advice and not test 9v batteries on the lower scale. I have also just ordered a new battery for it (the one you refered too). Thanks for that I did not think I would be able to find a replacement. I bought a varta that's what they have here same type though as the Energizer you talked about. I will keep you posted.

As for the other person who replied:-

The contact spray, does that have to be sprayed into the button on the outside or will I have to open the whole multimeter up and dismantle it all?

Thank you for the great help I will keep you both posted on how it works out. Kind regards, Peter.

[The Philpott]

Spraying from the outside won't reach the contacts properly, you will need to open it up (as you did in the photographs.) I do not think you will need to dismantle more than that just to clean dirty switch contacts. Time will tell! Do not get the spray on the moving parts of the needle and the display.

Given the choice of Energizer or Varta i would have chosen Varta anyway.

Dave

[Sinewave]

Originally Posted by Dred007

So I'm not sure I am allowed to ask for help but

Why not? What would make you think that?

[dseymo1]

Originally Posted by The Philpott

Spraying from the outside won't reach the contacts properly, you will need to open it up (as you did in the photographs.) I do not think you will need to dismantle more than that just to clean dirty switch contacts. Time will tell! Do not get the spray on the moving parts of the needle and the display.

While you have it apart, it will be worth using using contact cleaner on the main range switch too. Spray just a drop into each switch, then operate it vigorously a good few times to remove any oxidation etc. from the contacts. Similarly, clean the test sockets and plug / unplug the leads a few times. Be sparing, though, and keep the cleaner away from plastic components - the material used for some of these USSR instruments can easily be damaged.

[philthespark]

You have to understand a bit about translation sometimes to work out what is going on with something, in my opinion, the "internal power unit" is simply the battery!
I have dealt with loads of stuff from foreign countries and quite often the translation leaves a lot to be desired, sometimes it can be hard to understand, sometimes it can be quite comical. Even if you can't get the meter working it's still worth having, it's the memories behind it that matter, not whether it still works. After all, I assume you don't work in the same job as your grandfather. I have a few tools that belonged to my father, he's still alive although elderly, and I use these tools on occasions, it's funny using them and imagining my father having used them many years ago.
I was doing a job at the weekend and ended up using one of the large wrenches that I had got from my father. At the end of the job, I was tired, aching, covered in oil and had a clear memory of my father coming home from work in a similar condition many years ago. Happy memories, I only hope I can leave my son, or grandson with similar memories of me, although to be honest, while my grandson aged 11 is keen to get involved with anything I'm doing, my son prefers to leave it to me.

[MotorBikeLes]

First, I think it is a taut wire movement, not one mounted on pivots. As stated, the big knob is only for resistance ranges, the small central screw driver slot is the basic meter movement.
I suspect the missing reading on 15v range is an open circuit resistor, not a dirty switch, but I have not looked at the circuit, so that is only a guess.
The maximum current range is 1.5A, not 1500A (your leads would be 6" diameter for that!). 1500mA = 1.5 A.
That little pic about a 30v to 40v battery is a useful idea. If you add a battery in series, the very high resistance range will work, and very useful that would be for testing for leaky capacitors.
I suspect you need some tuition regarding the use of a meter, otherwise you will likely kill it, and maybe yourself too. Ask away.
Les.

[Dred007]

Originally Posted by Sinewave

Why not? What would make you think that?

Hi,

A lot of forums are different, thankfully this one has a wide range of amazing and welcoming people who are really great. I appreciate everybody taking the time to help me here.

Originally Posted by dseymo1

While you have it apart, it will be worth using using contact cleaner on the main range switch too. Spray just a drop into each switch, then operate it vigorously a good few times to remove any oxidation etc. from the contacts. Similarly, clean the test sockets and plug / unplug the leads a few times. Be sparing, though, and keep the cleaner away from plastic components - the material used for some of these USSR instruments can easily be damaged.

Hi thank you for replying,
I have found a contact cleaner here in Denmark I would just like to check if the ingredients sound similar to what you have.

Ingredients: 2-propanol, hydrocarbon, c7, cyclic, alkaner, iso-alkaner

Does that sound about like what you have?
I will clean all those parts you recommended when I get a confirmation that this contact cleaner is the accurate type of cleaner.

Thank you

Originally Posted by philthespark

You have to understand a bit about translation sometimes to work out what is going on with something, in my opinion, the "internal power unit" is simply the battery!
I have dealt with loads of stuff from foreign countries and quite often the translation leaves a lot to be desired, sometimes it can be hard to understand, sometimes it can be quite comical. Even if you can't get the meter working it's still worth having, it's the memories behind it that matter, not whether it still works. After all, I assume you don't work in the same job as your grandfather. I have a few tools that belonged to my father, he's still alive although elderly, and I use these tools on occasions, it's funny using them and imagining my father having used them many years ago.
I was doing a job at the weekend and ended up using one of the large wrenches that I had got from my father. At the end of the job, I was tired, aching, covered in oil and had a clear memory of my father coming home from work in a similar condition many years ago. Happy memories, I only hope I can leave my son, or grandson with similar memories of me, although to be honest, while my grandson aged 11 is keen to get involved with anything I'm doing, my son prefers to leave it to me.

Hi,

It is indeed interesting to read instructions in foreign languages, I speak three and Danish is the trickiest. The one I always find funny is "smør på" which literally means "butter on" )) so if you have oil or something they tell you to butter it on.

I think now that you mention it, I guess it can only be the battery? But I must admit at first I thought they meant a capacitor.

As for the nice story about your father, I do the same thing think of him going up 220 steps to get to his work it must have been wild! And yes I would actually love to use this multimeter and not just have it sit around. I will not have it lying around broken. Mission is for it to work and hopefully use it and pass it on to my son one day )) I know it can work again. Thank you for your lovely story and insight. Peter

Originally Posted by MotorBikeLes

First, I think it is a taut wire movement, not one mounted on pivots. As stated, the big knob is only for resistance ranges, the small central screw driver slot is the basic meter movement.
I suspect the missing reading on 15v range is an open circuit resistor, not a dirty switch, but I have not looked at the circuit, so that is only a guess.
The maximum current range is 1.5A, not 1500A (your leads would be 6" diameter for that!). 1500mA = 1.5 A.
That little pic about a 30v to 40v battery is a useful idea. If you add a battery in series, the very high resistance range will work, and very useful that would be for testing for leaky capacitors.
I suspect you need some tuition regarding the use of a meter, otherwise you will likely kill it, and maybe yourself too. Ask away.
Les.

Hi Leslie,

Thank you for your insight into the multimeter.
I will try and not kill myself but obviously I understand your concern. I myself have been electrocuted at 400v at my place of work. I was stuck to an electric cubbard for more time than anyone could wish for. My fingers where burnt, the worst of all was that I was very very depressed after. I'm quite sure it was because of the electrocution. I would have probably died because nobody would have been able to do anything but magically i dont know if it was gravity or what but I got off it. I remember all my muscles being tensed up and I could not control my body such a strange feeling. Anyway I survived it!!! Some don't.

So, the open circuit resistor, that's not something I will be able to test in the circuit right? I would have to take them off and test them out of the circuit.

I did also notice that There seems to be something that does not look normal but I'm not sure it has any affect on the workings of the multimeter, here are links to what I mean:

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****************/hnF3iy

Some strange kind of corroding?

[The Philpott]

Peter, i do not see any corrosion in those pictures, it looks OK. Are you looking at the white paint?

If the product you are using is sold as a 'contact cleaner' i see no reason why it should not be used for this.

Dave

[Dred007]

Hi,

Not the white paint but if you look at the second picture the center object has red stuff all.over it. It looks odd as if it wasn't designed like that. The first picture has the same thing on those components.

I don't know what that component is though, maybe a capacitor? Kind regards,

[dseymo1]

If I'm looking at the same thing, that looks more like wax or a similar sealant.
By the way, don't leave the meter in the sun - I found out the hard way that the panel markings fade badly!

[Refugee]

Those parts look like hand wound resistors.
The markings on the one in the second photo look like bubbles in the sealing wax under the insulating tape on another hand wound resistor.

[Dred007]

Hi,

Maybe that's just some sort of sealant or wax then.
In electronics there isn't much to see with the eye, it's mostly taking things out and testing them or am I mistaken?

If that was a handheld wound resistor, could it be replaced with a normal resistor available today or is there something special about a hand wound resistor?

Thank you guys so much for replying to my post, Peter.

[The Philpott]

A precision resistor with perhaps +- 1% tolerance will be totally adequate, one with +- 0.5% tolerance would be even better. Such modern resistors have colour code bands to tell you their resistance value and tolerance (accuracy). The higher the rating of the new resistor (in watts or millwatts) the better, from the point of view of stable accuracy. If the resistor is pushed too hard it can warm up and reduce accuracy.

You are correct, to check the resistance of a wire wound, or normal, resistor one end must be disconnected from circuit otherwise false readings can occur.

[Refugee]

With most meters if you have a circuit diagram you can set the controls so that the resistor under test is not connected.
In general the suspect resistor can be tested if the voltage switch is set to a more sensitive range than the suspect range is affecting.

[The Philpott]

Given a soldering iron, a cheap digital multimeter, some solder and a solder sucker i don't see any reason why you can't tackle it yourself cheaply if you have steady hand and it's something you want to learn.

bigclive on youtube covers all sorts of electronics and amongst his videos is a short soldering tutorial. A video paints a thousand words. It is easier if in Denmark you can get a small reel of old type solder of a tin/lead alloy with proper flux inside it.

It will be very good if you can find a helping hand locally to give you some tips, as this is quite a small meter and you might have troubles with access.

[The Philpott]

As has been hinted above, in use the voltage shown on your meter will not tell you the state of the charge of a battery or cell you are testing, as it is a quite sensitive meter and does not demand very much power from the battery it is connected to. The cells in a 3volt torch can be analysed by seeing how much the voltage drops when the torch is switched on. This 'volt drop' is a reliable indicator of the life remaining in the cells.

If you have not damaged the meter by applying 9 volts on the 1.5 volt range then it is a reasonably tough item. This is to be expected as Russia was very sensitive about it's home products being seem as inferior, and it is also almost certain that every component of the meter came from within their own borders.