Analog Multi-meter question,

[Big Wave D]

I have a nice old Micronta (Radio Shack) made analog multimeter. I needed to press it back into service for its 10amp, DC capability a few days ago. I was trying to track down some parasitic battery drainage on a vehicle.

It worked fine two days ago. Today I tried to use it and when I turned it on, it goes to full left deflection. In the On position, the Ohm and Zero adjustment knobs do nothing. Changing the dial between any of the settings does nothing either. If I turn the On knob to battery test, it does exactly as it should. It goes to the right to indicate battery strength.

I've checked the batteries and fuses and all are fine.

I'm kinda stumped. For it to have worked fine just a few days ago, and now this full deflection to the left today I'm experiencing. Yes, it could have just croaked today, but I'm thinking it is something I'm missing.

Any thoughts?

All ideas are greatly appreciated

 

[Ken]

I would check for the position switch the meter is being driven to the left by voltage so maybe a corroded wafer contact. or wire became loose. The bat.check is just a single switch to resistor to meter.
I have a stack of the little analog multi-meters. all one problem or another and unable to locate parts. Shipping prices excede the cost of new.
ken

 

[Big Wave D]

Hey Ken,

Thanks for the tips, I'll look and see if they lead to a "cure".

Yes, I fear that we live in the "Pitch Age". It kind of makes me sad that things are made SO cheaply that they have no intrinsic value to repair them. It's made a whole occupation almost extinct. Unless something costs almost $_______ or more(fill in your personal threshold), it's pitch it in the garbage and buy new.

Just a side question for curiosity sake, but what is YOUR(this question is open to anyone) pitch/repair dollar amount? $100, 350, 700, 1000, higher?????????

 

[Ken]

B.W.D. This depends on the personal value of what is being replaced. A multi-meter costing $9.99 Cannot purchase parts with out a mail order. I usually toss in the to be repaired later box. Have several of these. My digital cost around a $100 Would spend some time on looking for the problem.
When the dual trace scope went bad. the repair cost was more than another unit on e-bay. so now have almost total parts replacement for this tool.
My tractor when book keeper said costing $50. per hour of use for repairs. Put up for sale and purchased new tractor.
As said earlier depends on personal value what you have.
ken

 

[Big Wave D]

Ken,

I appreciate your response.

It seems like a person's age has a lot to do with how this question might be answered.

I posted this question to the main Parts/Repairs forum board. I'm kind of anxious to see what kind of a response this question gets.

Spread the word. The more input the merrier, I say.

 

[cityfarma]

I work on a percentage of the value of the faulty device taking into account the age.

Eg, a 10 year old TV is worth nothing then replace unless free repair. A 2 year old plasma worth $1000 and repair of $500 would be questionable. A 2 year old plasma worth $4000 and repair $1000 would be a repair. A repair of >50% of the value is probably a write off as a new device would also come with a warranty.

Cityfarma

 

[Treemonkey1000]

Are you sure the battery hasn't been put back in backwards on that thing? You sound familiar enough with the stuff so don't get offended. Depending on the Micronta a lot of them didn't have transistors in them which would drive the needle to the peg. You might just look to see if a piece of junk hasn't landed in there and shorted out some contacts. And last but not least those meters can develop poor solder connections which can do the same thing. Take a magnifier out and look for that unless you have really good eyes.
Another thought is make sure the Zero adjust pot for the Ohms hasn't opened up or something.
I work in an Calibration lab where we test electronic equipment for accuracy. I have been around those items a time or two.
My toss it factor is getting easier to do as I like to fix what I can. But I have a lot going and little space in my house so I tend to "donate" more now to the give away pile.

 

[bjr]

I've studied the new Z-drive lawn mowers and they appear to mostly use the Hydro-gear pump/motor drives. The Husquvarna dealer salesman said "Yeah there expensive to replace" as there's no rebuilding them and not supposed to ever add/check oil, "They never break Down". The drives are almost 3/4 the cost of a new machine. Just have throw away a $3000 machine and get new when it impossable happens. I'm gonna have to stick with my old mechanical drive Dixon, even if it's a bear to adjust all the components, Chain; bearings and sprockets belts are available at local bearing supply store and Agri-Supply has the blades. bjr

 

[Big Wave D]

Thanks to all who have posted helpful ideas of things to look at or for.

Just for kicks, I tried turning it on today and it "seemed" to work fine. I was using it to see if a Throttle Position Sensor was working or not.

The reason that I say "seemed" to be working okay was that when I was measuring battery voltage of said car's battery, it read consistently 1 volt lower than my little digital multi-meter.

I think I have the instructions still, but maybe what I need is a refresher course in setting up my Analog Multi-meter, Analog Multi-meter 101.

Here's a picture of it:

1) Under the white lettering "MICRONTA", what is this little slot screw used to adjust? (sorry, hard to see it in photo)

2) What is the proper usage of the Ohm's and Zero adjustment knobs?

Appreciate the help from anyone who takes the time to type all this out.

Thank you

 

[Treemonkey1000]

Thanks to all who have posted helpful ideas of things to look at or for.

Just for kicks, I tried turning it on today and it "seemed" to work fine. I was using it to see if a Throttle Position Sensor was working or not.

The reason that I say "seemed" to be working okay was that when I was measuring battery voltage of said car's battery, it read consistently 1 volt lower than my little digital multi-meter.

I think I have the instructions still, but maybe what I need is a refresher course in setting up my Analog Multi-meter, Analog Multi-meter 101.

Here's a picture of it:

1) Under the white lettering "MICRONTA", what is this little slot screw used to adjust? (sorry, hard to see it in photo)

2) What is the proper usage of the Ohm's and Zero adjustment knobs?

Appreciate the help from anyone who takes the time to type all this out.

Thank you

Analog meters are subject to errors from tipping if the movement is worn out a bit. Then reading errors from parallax errors (when you are looking at the needle from the side instead of from above) And some of them aren't very accurate to begin with. Your DVM could be off as well. Typically though the DVM will give you more accurate readings.
For the ohms mode you want to short the test leads together on the lowest range that you will be measuring. Then adjust the zero pot for 0 Ohms on the meter. As you change ranges you will probably have to rezero it for the most accurate readings.
Be careful measuring voltages of course like being on DC Volts for DC readings and AC Volts for AC. Some meters won't tolerate being hit too hard with high voltages on low ranges.
One thing you might check is to see if the needle moves back and forth smoothly? If the spring is weak or damaged or the pivots are worn the needle will not move smoothly. That can give you reading errors.

 

[Ken]

B.W.D. This screw is to place the pointer to 0 when no voltage on meter. be careful go to far and messes up the setting stop.
On the ohms setting touch the leads together pointer should go to 0 on the scale then release pointer should return to full scale on the meter scale.
if not then adjust by again touching the leads together and one of the adjustment knobs should. then open and adjust to full scale reading each adjustment effects the other.
Depending on the grade of the components inside this should work.
ken

 

[Big Wave D]

I really appreciate the refresher course on the use and set up for my Analog Meter.

Have had several situations here lately that have dictated the use of both my meters for testing.

Watching the sweep of the meter arm was very helpful while troubleshooting whether or not a TPS was good on a car I was working on. My digital would give readings of course, but with Auto Ranging, it always goes through several permutations before it settles on the final number. Therefore, it's kind of worthless to see if the TPS had a bad spot. With the analog, being able to see a nice smooth needle swing with no jumps or spikes, I was getting a more thorough picture of the parts correct function.

 

[Bird]

Just a side question for curiosity sake, but what is YOUR(this question is open to anyone) pitch/repair dollar amount?

I used to rebuild/repair all kinds of mechanics' air tools, and the usual thing in that business was to fix it if it could be done for half or less of the cost of a new one. Some customers asked for estimates first on anything, and I sure couldn't blame them for that. Some never asked for estimates, but if it was going to cost more than about a third the cost of a new one, I called them anyway to ask what they wanted to do.

 

[Car Doc]

Big Wave,

While you are at the electronics store getting a new meter pick up a 10 watt 1.0 ohm resistor.

Place it in series in the negative battery cable and then the car is powered by the resistor not your meter. (those internal meter fuses are usually a pain to replace and or find)

Attach the leads of your meter across the resistor to accurately measure the voltage drop to measure the draw. Using the low volts scale and the readings will be IE .030v would equal 30ma. hth

Steve

 

[Big Wave D]

Big Wave,

While you are at the electronics store getting a new meter pick up a 10 watt 1.0 ohm resistor.

Place it in series in the negative battery cable and then the car is powered by the resistor not your meter. (those internal meter fuses are usually a pain to replace and or find)

Attach the leads of your meter across the resistor to accurately measure the voltage drop to measure the draw. Using the low volts scale and the readings will be IE .030v would equal 30ma. hth

Steve

Car Doc,

Thanks for the advice.

For a little clarification, for me, are you saying I should take the Resistor, solder some leads onto its ends, put some aligator clips on the ends of the leads, and then for proper use, clip alligators to (-) battery terminal and (-) battery cable?

Once this is done, take reading off of resistor, by touching both sides of resistor with meter leads?

I would be using this method as a means of determining Parasitic Battery Drain? That's what I'd gotten my old Analog Meter out to do in the first place. It has the 10 AMP, DC setting. My little DMM can only read to 200mA. Needless to say, it smoked the fuse in a heart beat.

 

[Car Doc]

Car Doc,

Thanks for the advice.

For a little clarification, for me, are you saying I should take the Resistor, solder some leads onto its ends, put some aligator clips on the ends of the leads, and then for proper use, clip alligators to (-) battery terminal and (-) battery cable?

Once this is done, take reading off of resistor, by touching both sides of resistor with meter leads?

I would be using this method as a means of determining Parasitic Battery Drain? That's what I'd gotten my old Analog Meter out to do in the first place. It has the 10 AMP, DC setting. My little DMM can only read to 200mA. Needless to say, it smoked the fuse in a heart beat.

Big Wave,

You are understanding very well yes the alligator clips will make the connections easy and yes use the negative battery cable to test drain and yes just connect them across the resistor it protects your meter and gives an accurate reading, you are converting voltage drop into amperage.

You would be reading volts though and its directly relative to amps in that while reading a DVOM on low volts scale you are actually reading the mili amps, a digital meter works the best especially an auto range type like you have. Got any more questions I will answer the best I can have fun

Btw a +200ma draw is severe 50ma is about the max on a late model car w/multiple ECU's you may smoke the resister as well but it wont kill your meter that's the good part fwtw

Steve

 

[Big Wave D]

Car Doc,

1994 Olds 98 Regency w/3.8, naturally aspirated.

Surely this qualifies as late model.

So if the 50mA thing is an average Parasitic Draw, then if I smoked my meters fuse, something's amiss.

I was having this random dead battery problem. Start fine for a week or two, then might have to jump it.

The battery was less then 2 months old. Just replaced the previous AC Delco that had been in it. Also, the alternator is less than 2 years old.

I found spot on internet that gave voltages for car battery at 100%, 75%, ... Anyway, 12.78 volts they called 100% charged. My battery would never read past their 50% value. With car running, I would read about 14.12 volts which seems to be on the good side of normal, and with all heavy load items going full blast, it still would read 13.8+

I thought that with the meter readings it was pointing to the battery, or now, I might say that the battery was part of the problem. I'm concerned then about the fuse blowing on my tester. That seems to indicate I still have to much draw, and that I'm going to be killing this battery off soon too.

Thoughts?

Thanks again

 

[Car Doc]

Big Wave,

Battery's cant be checked with a volt meter they need a actual load test to know for sure, GM alternators leave a lot to be desired imo I don't trust them as far as I can throw one and bargain parts store remans are the worst fwtw.

Right off I cant think of a common pattern failure on that car, ignition switches can be a source of trouble and are harder to diagnose than most electrical switches just because of their position in the car and the fact that's where a lot of your power goes thru the fuse boxes.

The first thing I do when I have a batt drain come in to my shop I load test the battery then I look for things that someone has added to the car then if there isnt anything or after I un-plug it and still have my drain I unhook the alternator at the big B+ terminal and see if it goes away thats the first thing. Alternators can drain w/o causing any other symptoms besides they stay warm long after the car is shut down and can still produce acceptable amounts of power as far as a simple meter voltage test.

Next is isolating which circuit is causing it, the way I do this is start unplugging things one at a time while watching my meter or test light, you also use the 12v test light in series with the neg batt cable for the rough measurement I stress "rough" it doesn't take much to light one up but it does help diagnose.

I use it first sometimes its easier to see when you are cramped under a dash and you can add longer leads to bring the light inside the car with you if necessary.

The light will dim when you get close to your problem when un-plugging things but after that its a meter measurement to determine if its acceptable or not. Its not an exact science using a test light fact it can throw ya off track so just use it as a tool to get close to where you need to be. Pull the trunk light bulb first thing also just because.

Keep in mind the door button for dome light can have a count down dimmer timer that will reset each time you open the door etc and even a seatbelt or door open light on the dash and cause a large draw right away and then dwindle down and the computers wake up each time the key is turned on and the body computer will wake up with the door opening and they take sometimes 20 minutes to go back asleap keep that in mind also dont get in a huge hurry. If I need to be in the fuse box under the dash I usually dis-able the dome light either by pulling the fuse for it or making a block that pushes the button while I have the door open. I am creative so it depends on the car how I do it.

If you have any more questions I will be happy to add ideas.

edit: I may add that when you un-plug the B+ at the alt also (with key off) pull the small wire also off it and check it for voltage at the wire not the alt, this will test to see if the PCM is powering the alt with the key off. It will be hot with key on normally and thats what turns the alt on when its working properly, it doesn't mean the alt is good though we are just checking the car itself.

Steve

 

[Big Wave D]

Car Doc,

THANK YOU so much for the more likely places to look first.

So far, everything seems to be acting normal.

Can a load test for battery done with any accuracy with the battery in the car or should I pull it and let them bench test it?

Thanks again

 

[Car Doc]

You are welcome!

Yes you can test it in the car that's how I almost always do it I hardly ever even take the terminals off. Parts stores usually will test them for free since they are happy to sell battery's you can ask one of them.

Seeing the amount of spark when touching a terminal to a battery post gives some idea how much drain is present also a small amount is normal but if its enough to transfer any lead its probably too much fwtw.

Steve