Hi! I have a mobile phone which has a blank screen but working. When attached to computer via usb, a tool is telling that its battery is -1% (eventhough it has a voltage of around 4.1).
Can someone pls. identify the attached component. I believe that this is a (current sensing, ultra low) resistor but its code (010) doesnt not correspond to any valid resistor code, not unless it is actually R010. When measured, it shows .2 ohm (starts with .5 then settles with .2) which i believe is wrong, it should be .01 ohm
Thanks!

 

Surface mount resistors are labeled with their value using a 3 "band" code. 010 would be 1 ohm.

When measured, it shows .2 ohm (starts with .5 then settles with .2) which i believe is wrong, it should be .01 ohm

I'm assuming that you're measuring in-circuit. If that's the case, you need to understand how other components are interacting with the component you're trying to measure.

 

case code 010 for a resistor should be 1Ω
If you just have a basic dmm I doubt it would read it accurately even out of circuit. Its probably ok. Usually you can see when they have issue's or the resistance will be considerably higher then it should be.

 

Surface mount resistors are labeled with their value using a 3 "band" code. 010 would be 1 ohm.
I'm assuming that you're measuring in-circuit. If that's the case, you need to understand how other components are interacting with the component you're trying to measure.

Thanks for the reply. The battery has been detached from the circuit board for days but the resistor is still attached. Just an honest and "no formal education" question, will the other components still interact when the resistor is measured?

Thanks.

 

case code 010 for a resistor should be 1Ω
If you just have a basic dmm I doubt it would read it accurately even out of circuit. Its probably ok. Usually you can see when they have issue's or the resistance will be considerably higher then it should be.

It is still in circuit. I have a new and unsoldered 0603 1 ohm (01Y) smd resistor and I measured it using the same dmm, it yielded 1.2 ohms. If the attached resistor (010) is indeed 1 ohm and I measured it as .2 ohm and the new and unsoldered 1 ohm as 1.2 ohms, does my dmm is still not working near accurate? I'm asking this just to determine if I need a new dmm. Pls. also note that I am just a hobbyist without formal education on electronics.

Another question, is it normal for a 0805 smd resistor to have a base of color white? I usually see a black base... This is the reason why I asked if the resistor is a current sensing and ultra low resistor (with a wrong code...) because I saw that this type of resistors are usually having white base color.

Thanks.

 

Just an honest and "no formal education" question, will the other components still interact when the resistor is measured?

Yes. A DVM (or analog meter) has to apply a constant to measure resistance (they actually measier the voltage genrated across it). The voltage and current depends on the particular meter used. Accurate component require it to be isolated so it can't interact with other components.

 

Yes. A DVM (or analog meter) has to apply a constant to measure resistance (they actually measier the voltage genrated across it). The voltage and current depends on the particular meter used. Accurate component require it to be isolated so it can't interact with other components.

Thanks. Another question if you don't mind... Is the resistor I attached an ordinary (with 1 ohm resistance) and not a heat sensing and ultra low resistor? I'm asking this because I usually see smd resistor to have black base, this one has white base similar to heat sensing resistors...

Thanks

 

Is the resistor I attached an ordinary (with 1 ohm resistance) and not a heat sensing and ultra low resistor?

Can't say for certain whether it's temperature sensitive (a thermistor). There's nothing ultra low about 1 ohm.

I'm asking this because I usually see smd resistor to have black base, this one has white base similar to heat sensing resistors...

What you're referring to is just paint used for the overcoat. The base is ceramic.

 

Can't say for certain whether it's temperature sensitive (a thermistor). There's nothing ultra low about 1 ohm.
What you're referring to is just paint used for the overcoat. The base is ceramic.

Thanks. Now, since I measured it while still soldered to the circuit board and considering the interactions of other components, is it possible that a "good" 1 ohm resistor will measure .2 ohm like I previously measured?

 

Resistors in parallel reduce their overall resistance. Resistors in series increase the resistance. So since this single resistor by itself is reading a very low resistance then it is because the rest of the circuit is acting like a huge resistor. Here are some examples:

Two 10Ω resistors in parallel will read 5Ω
Two 10Ω resistors in series will read 20Ω
Two resistors; one at 100Ω and one at 1KΩ in parallel will have a total resistance of 90.9Ω

When two resistors are in parallel the total resistance will be less than the lowest resistor. In the last example the lowest resistor was 100Ω. When paralleled with 1KΩ the total effective resistance is 90.90909Ω
Here's how I came to that conclusion:
(1÷100Ω=0.01) And (1÷1000=0.001) So 0.01 + 0.001 = 0.011. THEN 1÷0.011=90.9090••• Hence, the two resistors in parallel equal 90.9Ω.

In circuit, your board is acting like a second resistor in parallel. Reading 0.2Ω confirms the 1Ω resistor is not burnt out or open. It tells me the rest of the board acts like at least slightly more than 0.2Ω since the total resistance will be less than the lowest resistor. Now, without knowing the rest of the circuitry I can't begin to guess how it affects this resistor. I also don't understand why a 1Ω resistor would be placed across the load (the load being the rest of the circuitry) unless it's there as a part of a short circuit protection diode, though I wouldn't understand exactly why. I only say this because you mentioned the battery power being interrupted, so I've automatically assumed it was a part of the main power input. It COULD be a totally different part of the circuitry and the designer wants to steer some current away from something else. To be able to answer how or why it's even there we'd have to know more about the circuit. But on the basis of your question, yes, it's a 1Ω resistor.

Most resistors I've seen have a black top. The underside is most often white. But that there are numbers on it reduces my certainty. However, it certainly does LOOK like a resistor. One way to tell for sure if it's a resistor is whether there is metallization on five sides on one end of the resistor or just three. An SMT resistor has metallization on the top, bottom and face of each end. Capacitors and many other devices have metallization on those same three surfaces AND on each side for a total of 5 sides per end.

 

Now, since I measured it while still soldered to the circuit board and considering the interactions of other components, is it possible that a "good" 1 ohm resistor will measure .2 ohm like I previously measured?

Yes.

Your DVM and measurement technique can also introduce error.

What does your DVM read when you measure the resistance of your leads? What is the accuracy of your DVM on the scale you're using?

 

Yes.

Your DVM and measurement technique can also introduce error.

What does your DVM read when you measure the resistance of your leads? What is the accuracy of your DVM on the scale you're using?

it reads .4 ohm when test leads are touched together. I did try to calibrate it by putting it into manual mode (it is auto range) and selecting the highest range (M ohm 0.L) then touch leads together but it won't go down to 0 ohm. I also cannot remember where i put its user manual.

Anyway, with your explanations, I'm convinced that the resistor is good and it's time for me to look for another reason why I'm having problem with the display of my mobile phone. I will be creating another thread that will ask what are the components that are used to indicate the battery voltage of a mobile phone because this is exactly the cause of the blank display of the phone.

Thanks.

 

Resistors in parallel reduce their overall resistance. Resistors in series increase the resistance. So since this single resistor by itself is reading a very low resistance then it is because the rest of the circuit is acting like a huge resistor. Here are some examples:

Two 10Ω resistors in parallel will read 5Ω
Two 10Ω resistors in series will read 20Ω
Two resistors; one at 100Ω and one at 1KΩ in parallel will have a total resistance of 90.9Ω

When two resistors are in parallel the total resistance will be less than the lowest resistor. In the last example the lowest resistor was 100Ω. When paralleled with 1KΩ the total effective resistance is 90.90909Ω
Here's how I came to that conclusion:
(1÷100Ω=0.01) And (1÷1000=0.001) So 0.01 + 0.001 = 0.011. THEN 1÷0.011=90.9090••• Hence, the two resistors in parallel equal 90.9Ω.

In circuit, your board is acting like a second resistor in parallel. Reading 0.2Ω confirms the 1Ω resistor is not burnt out or open. It tells me the rest of the board acts like at least slightly more than 0.2Ω since the total resistance will be less than the lowest resistor. Now, without knowing the rest of the circuitry I can't begin to guess how it affects this resistor. I also don't understand why a 1Ω resistor would be placed across the load (the load being the rest of the circuitry) unless it's there as a part of a short circuit protection diode, though I wouldn't understand exactly why. I only say this because you mentioned the battery power being interrupted, so I've automatically assumed it was a part of the main power input. It COULD be a totally different part of the circuitry and the designer wants to steer some current away from something else. To be able to answer how or why it's even there we'd have to know more about the circuit. But on the basis of your question, yes, it's a 1Ω resistor.

Most resistors I've seen have a black top. The underside is most often white. But that there are numbers on it reduces my certainty. However, it certainly does LOOK like a resistor. One way to tell for sure if it's a resistor is whether there is metallization on five sides on one end of the resistor or just three. An SMT resistor has metallization on the top, bottom and face of each end. Capacitors and many other devices have metallization on those same three surfaces AND on each side for a total of 5 sides per end.

Thanks for all the informations! You were right, this resistor is directly above the battery connector. With all the replies from this thread, I'm convinced that this resistor is good. Now it's time for me to focus to another thing in search for the answer why my mobile phone has blank screen but working and when connected to a tool, it says the battery is at -1% whereas it is fully charged. I will be creating another thread that asks what are the components that are responsible in indicating the battery charge level of a mobile phone.

Thanks.

 

Yes.

Your DVM and measurement technique can also introduce error.

What does your DVM read when you measure the resistance of your leads? What is the accuracy of your DVM on the scale you're using?

Hi! I just created a new thread... If you have an idea, probably you can reply to it...

https://forum.allaboutcircuits.com/...attery-charge-level-of-a-mobile-phone.164240/
Thanks

 

A more fundamental question is why do you suspect the resistor is related to the blank screen? Phone screens have both drivers for the display and backlights, two very different circuits. A blank screen on an otherwise working phone points more towards a broken screen connection, possibly due to dropping the phone.

 

A more fundamental question is why do you suspect the resistor is related to the blank screen? Phone screens have both drivers for the display and backlights, two very different circuits. A blank screen on an otherwise working phone points more towards a broken screen connection, possibly due to dropping the phone.

The backlight is working as it blinks/lights whenever i press any button, the lcd isn't. I also read a thread having same problem in which the thread starter claims that he is seeing that -1% battery shown very quickly every around 10 on-off of the phone. Also, looking at the pcb, this is the resistor right above the battery connector which when i measured is way far from what is supposed to be (you have to forgive me for this as i am just a hobbyist without formal electronics education and not understanding that eventhough the battery is already disconnected, ad long as it is still soldered to the pcb, other components will still affect its reading)
Thanks

 

I also read a thread having same problem in which the thread starter claims that he is seeing that -1% battery shown very quickly every around 10 on-off of the phone.

I thought YOU were the "TS" (Thread Starter).

If the screen is showing -1% momentarily then it's not an issue with the screen. It may be a bad processor. This is beginning to sound like something WAY over my head. Then again, HAIR is way over my head.

 

I thought YOU were the "TS" (Thread Starter).

Another thread on another forum I am sure.

 

I thought YOU were the "TS" (Thread Starter).

If the screen is showing -1% momentarily then it's not an issue with the screen. It may be a bad processor. This is beginning to sound like something WAY over my head. Then again, HAIR is way over my head.

I am just trying to correlate my problem with another forum discussion in which a commentor (not a thread starter, my mistake) claimed seeing that message. I am attaching a screenshot of the same message coming from my OWN defective device having same error message.
I never saw

I thought YOU were the "TS" (Thread Starter).

If the screen is showing -1% momentarily then it's not an issue with the screen. It may be a bad processor. This is beginning to sound like something WAY over my head. Then again, HAIR is way over my head.

I am just correlating my problem with another forum discussion in which a commentor (not a thread starter, my mistake) said seeing that -1% battery message being shown in his device's screen very quickly as i also saw same message when i attached my device to my pc and used a tool. I am attaching a screenshot of that message when i atrached my OWN device.

From the beginning, I never thought it is a lcd problem. What i believe is it is either a software problem (because the device is working. It would NEVER boot if there is a lcd problem, its power on self test would catch the lcd problem and will not boot) or problem with the component that senses the battery voltage (because of the -1% battery message).
Thanks.

 

Another thread on another forum I am sure.

Yes, you are right. It is because i am researching and trying my best to find answer to my problem, so i will process any info (and hope that it helps me) that i will find that i believe relates to my problem.
Thanks.