Fixing a multi meter?

[Arugela]

Not sure if this should go here or in the lounge. It's technically science/engineering.

I accidentally put too much pressure on a little copper part within my multimeter. It is a part that makes a connection between the wheel/setting selector and the board while putting it back together. It split the copper in half at both ends and no longer can act as a connector reducing proper function of the multi meter from what I can tell. It's literally beeping constantly when set to voltage.. Not sure what that even means as I'm new to this sort of things.

Here is a vid showing different multimeter with the exact same wheel and copper peices. I'm trying to either figure out a way to repair(solder isn't working. I have cheap solder.) replace or find an alternative to these pieces. I think I"m actually missing two in this case. I actually need to figure out how many it should have and which slots it should be in. I'm assuming the wheel is designed for varying multimeter and they stuck in the ones in the correct place or something.

I tried to fix the copper by using solder to reconnect it, but I was having difficulty getting it to resit. And if I used less solder it would not stay together. Then I burned myself slightly on the iron and stopped... Might try again later.

I have a craftsman autoranging multimeter 82175.

Vid showing part:

Starting the video will put you a few seconds before it shows the inside of the wheel selector.

There are 7 of them on this multimeter. 4 on one side and 3 on the other. I think it's the same configuration mine originally had.

Pic:

Edited May 22, 2018 by Arugela

[mikegarrison]

https://imgs.xkcd.com/comics/repairs.png

Edited May 22, 2018 by mikegarrison

[Shpaget]

If you are getting angry beeping, that would indicate that the probes are not inserted into the slots the meter is expecting them, in relation to the selector switch. Since the selector switch is broken, it's no wonder the meter is confused.

It's hard to diagnose the fault and offer precise instruction for repair without seeing the unit itself, however contacts are pretty small and soldering will only make them shorter. You could try to add a small piece of brass plate on the contact to patch them without shortening them, but it's a fiddly job. In your place, I'd try to find a broken or "for parts" unit on ebay and transplant the brass contacts, or entire selector. 

[Gargamel]

Take a hard look at how much effort you are going to put into repairing this thing, vs the cost of new one.  A very usable meter these days is pretty cheap. 

[Nuke]

i found one in the dumpster a few months ago. didnt work. needed a fuse. disnt have a fuse. had tinfoil. wrapped dead fuse in tinfoild. working multimeter. just dont forget about it when you need to test high current things. 

[Arugela]

I didn't think about that. I wonder if I can tin tinfoil or use tinfoil to secure or make a new contact. I just need to make one out of something cheap. And I think I need to make two of them which could be interesting. As I split one in two accidentally down the middle. Maybe I can find a way to make it into two seperate contacts. It just needs to be strong enough to take the abuse of turning the knob...

Maybe If I press tin foil really hard and make a sudo solid contact and mold it. Might be a fun project.

[YNM]

TBH, given the shape of the connectors, seems like you'll have to replace them. Unfortunately I don't know many metal ribbon materials out there. I can see that the original manufacturer didn't install rigid connectors because they'd slowly wear the PCB, so it instead "sacrifice" the connectors.

Some tinfoils have a plastic surface over it.

I was thinking some metal "shedding" that you get off milling. But they could possibly be too thick (stiff).

Another option would be neatly arranged fine wires.

Edited May 22, 2018 by YNM

[Shpaget]

I would advise against bodging the material. The existing contact is likely some sort of springy brass alloy, but more importantly has a specific geometry.

Go to a dollar store and buy any multimeter and gut it for the material.

[Arugela]

I forgot the other option... 8)

 

Does anyone know which contacts can be missing to allow voltage readings or how many can be missing. I only need voltage readings! >< I'm still in the process of trying to figure this out.

 

I think all of those multimeters are literally using the same PCB board cut differently and the wheel is identical along with the tracing. I think I lost one years ago and it still worked because it wasn't needed for what I was using it for. But I just broke a second one and now it's not working properly for voltage readings. Still trying to figure out which connections must exist for basic non powered readings to look for a short in a few things real quick. 8d

Yes, it is a very specific material and shape. They are based on tension. They have just enough to take the force of the ball bearings and the plastic ridges being pushed while turning the wheel and to hold themselves onto the plastic bits which also use tension. And the spacing to connect is very thing without creating a short or cross. Every time the wheel turns it is literally on a new mini pad. So, it cannot change position. Unless I can think of something clever. I don't know how easy it would be to fabricate one.

I also think it needs a minimum of 6 to work.. Maybe all 7.

 

Edited May 22, 2018 by Arugela

[Nuke]

did you try cleaning the contacts? because thats usually all thats needed. i think id just use a dremel sand disc with a really fine grit at lowest possible speed, being careful not to eat the whole bit o metal. though i think id start with a q-tip and vodka (or rubbing alcohol but i like a cleaner you can drink). 

[Arugela]

I lost two of those internal pins. They act as connectors on the wheel. I need to find replacements for them. I tried to solder the one i have back together, as it split in two physically from accidental pressure. But I could not get it to hold and be able to fit back on the device correctly.

[Gargamel]

If (Cost of New meter < (Time x How much you value your time) + materials used)

Return "Waste of Time"

Else

Return "Carry On!"

[Arugela]

I was trying to find a way to fix it just for the sake of doing it. More the challenge to find a way to do it. And I was hoping to fix it with something around me to save time. But, yes, I probably need to buy a new cheap multimeter to start testing stuff. Or do they sell those little metal things somewhere? Does anyone know what they are called. I'm not even sure to look them up.

Edited May 26, 2018 by Arugela

[MaverickSawyer]

On 5/22/2018 at 1:25 AM, Gargamel said:

Take a hard look at how much effort you are going to put into repairing this thing, vs the cost of new one.  A very usable meter these days is pretty cheap. 

Yep. Find your nearest Hazard Fraught err... Harbor Freight ad and see if they have that little multimeter as the frebie this week. For most diagnostic work, it's more than adequate.

[Gargamel]

11 hours ago, Arugela said:

I was trying to find a way to fix it just for the sake of doing it. More the challenge to find a way to do it. And I was hoping to fix it with something around me to save time. But, yes, I probably need to buy a new cheap multimeter to start testing stuff. Or do they sell those little metal things somewhere? Does anyone know what they are called. I'm not even sure to look them up.

I give ya a like, but I'm out for the day.  I'm with ya on that one, I love rehabbing old stuff on the cheap.   But if the thing I'm rehabbing is cheap to start with.

As @MaverickSawyer said, Hazard Frought is a good place to start.  I got a decent one off amazon a while back for a song too.   

If this was an oscilloscope, and you were just repairing a switch, then I'm with ya, but it's just a chintzy meter

[wumpus]

Multimeter's come in two varieties: Calibrated Flukes for formal testing, everything else for troubleshooting.  Many shops like to use only calibrated Flukes, just to make sure that nobody grabs the wrong one during test (the costs of using the wrong one outweigh the cost of keeping a Fluke calibrated), but if you don't need formal paperwork for your testing the "Harbor Freight" special is likely good enough (maybe somebody knows of "in-between brands", but I doubt there is enough of a market to bother).

- I have a 30+ year old Circuitmate (had to dig it out to check the name).  A Chinese co-worked was impressed (I'm sure it had *zero* name in the states when my parents bought it for me), but I suspect that "Circuitmate" might be almost as expensive as Fluke (or might not and just be riding on the old name.  All I know is that it still works after all these years).

[Shpaget]

I have Brymen BM235, the EEVblog branded version (well, three actually), and a UNI-T UT58D. The Brymens are quite impressive I like them a lot. UNI-T is fine.

Additionally I have UNI-T UT81B Scopemeter (painfully slow, but sometimes the battery powered oscilloscope feature is exceptionally useful, unfortunately it has only one channel) and a proper entry level bench oscilloscope (RIGOL DS1054Z) which has 4 channels.

There is a tool for every job, and the ones I have are probably too expensive for a very occasional tinkerer that doesn't work on mains, but everybody that does electronics should have at least two multimeters, one of which should be a proper device and not something you get for free at Lild/Horror Fright.