How to find value of /alternative Ceramic SMD (burned) capacitor value

Thread Starter

prerakk

Joined May 21, 2015
23
hi friends ,

i am tryin to fix EPS module board of my hyundai i10 car. after dissembling it , i find a burned ceramic SMD capacitor (non polar). the board dont have any markings on it about the components,and the EPS is not working in my car.

i have attached the images of module circuit.please let me know if its possible to calculate the value using multimeter , also if there could be other error that caused it.

thanks in advance
 

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dl324

Joined Mar 30, 2015
11,587
i have attached the images of module circuit.please let me know if its possible to calculate the value using multimeter
You can't measure the capacitance if it has been damaged. Size won't tell you much because the physical dimensions are standard for all caps in that package; aside from height.
 

dl324

Joined Mar 30, 2015
11,587
so what are my options now ??
Your best bet is to buy a replacement board. Even if you managed to replace any components you think are defective, you have no way of exercising all functionality on the board to verify that it can work as expected.

I had to google what EPS could mean. I assume you mean Electronic Power Steering and not Expanded PolyStyrene. Which was the first hit in my search:
1597774473385.png
 

Irving

Joined Jan 30, 2016
1,020
What's the black device next to it, Markings? Try to trace the circuit to see what it was doing. From the look of it, the black device next to it connects to one side of the relay coil, so I'm guessing that device is a diode for transient suppression and the capacitor, not being associated with a chip, is just bulk noise suppression to meet EMI requirements, between the 12v rail to the relay and ground. In which case its probably 100nF/50v. But you should find it'll work fine without it... assuming nothing else is damaged...
 

Thread Starter

prerakk

Joined May 21, 2015
23
Your best bet is to buy a replacement board. Even if you managed to replace any components you think are defective, you have no way of exercising all functionality on the board to verify that it can work as expected.

I had to google what EPS could mean. I assume you mean Electronic Power Steering and not Expanded PolyStyrene. Which was the first hit in my search:
View attachment 215058
As i already mentioned its from my car so it should be EPS . buying replacement board will be last option for me . i am trying to get the same board fix to save the environment.if everybody changes it for small faults.



What's the black device next to it, Markings? Try to trace the circuit to see what it was doing. From the look of it, the black device next to it connects to one side of the relay coil, so I'm guessing that device is a diode for transient suppression and the capacitor, not being associated with a chip, is just bulk noise suppression to meet EMI requirements, between the 12v rail to the relay and ground. In which case its probably 100nF/50v. But you should find it'll work fine without it... assuming nothing else is damaged...
the markings with marker ? i dont know , when i opened it, it was already there.and yes the capacitor is near to diode near 12v rail and not being associated to any ic/chip nearby.
 

Irving

Joined Jan 30, 2016
1,020
No, I meant any markings on diode? Was capacitor on 12v rail to ground? After it failed short circuit what else blew? A fuse?
 

dl324

Joined Mar 30, 2015
11,587
i am trying to get the same board fix to save the environment.if everybody changes it for small faults.
You'd risk your life and the lives of others to save the environment? A malfunctioning EPS could result in the lack of power steering.

I've steered a vehicle that lost power steering. Injured both shoulders and elbows in the process.
 

Thread Starter

prerakk

Joined May 21, 2015
23
No, I meant any markings on diode? Was capacitor on 12v rail to ground? After it failed short circuit what else blew? A fuse?
yes the diode says sj1c / s1jc (attached zoomed image for ref). and if by fuse u mean that in car compartment , No.

IMG_20200819_105552.jpg

Is the capacitor short circuit?
It doesn't look to me like the solder melted, it looks more like it was mechanically removed.
the solder was melted at time i dissembled it. removed by tweezer, but connection is fine on both side.

You'd risk your life and the lives of others to save the environment? A malfunctioning EPS could result in the lack of power steering.

I've steered a vehicle that lost power steering. Injured both shoulders and elbows in the process.

thats why i am trying to get it fixed with proper guidance.
 

Irving

Joined Jan 30, 2016
1,020
yes the diode says sj1c / s1jc (attached zoomed image for ref). and if by fuse u mean that in car compartment , No.
Yes, that's a 1N4005 equivalent.

So, the question remains, if the capacitor was short circuit (and does it test as short now?) what stopped the wiring/tracks burning up? Is there some other fault? If it burnt out and is no longer short, why did the EPS stop working?

Have you tried the EPS again after removing that capacitor?
 

Thread Starter

prerakk

Joined May 21, 2015
23
Yes, that's a 1N4005 equivalent.

So, the question remains, if the capacitor was short circuit (and does it test as short now?) what stopped the wiring/tracks burning up? Is there some other fault? If it burnt out and is no longer short, why did the EPS stop working?

Have you tried the EPS again after removing that capacitor?
hi . i guess there should be or should be not , i tried the EPS after removing capacitor but it doesn't work.i have no idea in checking other errors in this kind board
 

Irving

Joined Jan 30, 2016
1,020
hi . i guess there should be or should be not , i tried the EPS after removing capacitor but it doesn't work.i have no idea in checking other errors in this kind board
Well if it's still not working, replacing that capacitor is unlikely to resurrect it. Its likely that rail was a regulated supply from BATT+ (battery, 10 - 14.4v) and was probably regulated to either 10 or 12v (that relay is guaranteed to pull-in at 9.2v & 10v from battery is when cranking and EPS not required to be functional then). So possibly the regulator has failed. If you plug the EPS board in and check the voltage across that capacitors pads it should be 10v or more. If not then its probably a dead regulator (there's at least 4 or 5 candidate parts there) or a blown on-board fuse (though I don't see one). Without more experience in electronics fault finding/repair its going to be hard for you to diagnose & fix this - replacement is your only option.
 

andrewmm

Joined Feb 25, 2011
574
A note.
If the EPS is as we think a safety critical system,
then you changing anything leaves you with a dilemma.
All car insurances I know ask, have there been any modifications made,
as you are not in the insurance companies eyes qualified,
you have made a modification to what sounds like a safety critical system.

as such, your insurance will be null and void.
Any injury or damage inflicted , to yourself or more importantly others,
is at your expense,

I would also imagine, if you killed some one in an accident ,
you would be criminally liable for at least man slaughter.

Are you in a state that had the death penalty for man slaughter ?
 

Irving

Joined Jan 30, 2016
1,020
@andrewmm et al

<flame suit on>
Surely that's for the TS to decide, is this the right forum for such? I understand where you're coming from, but we must be careful of politicising an intellectual exercise. And in extrapolation are we then saying "Its safety critical so don't go and buy one from a breakers yard/refurb outlet, take it to a main dealer and let them do it?" What about systems no longer available through main dealers? And then, by further extension, are we stating that we are against the "right to repair" legislation in the EU and, increasingly elsewhere? What constitutes a 'safety system' and how is such defined by law? In the US & EU, Apple, for one, is trying to argue against board-level right to repair by independents; you may say "oh but that's not a safety system", but in at least one US state, right to repair was thrown out by legislators paid for by lobbyers who are funded by major players such as Apple. Their (IMHO spurious) argument, accepted by legislators, is that repairing phones by other than their authorised repair centres could lead to an increase in screens cracking and glass getting into infants causing major injury or death. I kid you not! Except of course Apple don't repair iPhones or MacBooks, they just want to sell you another one...
</flame suit off> :)
 

andrewmm

Joined Feb 25, 2011
574
@Irving

I was just highlighting what legal situation the user could be in, and the implications. As you say, Its up to the user to decide .

And just a thought, with the legal system in the US being what it is,
I wonder if it could be argued that any help we were giving on a safety critical system, would put us liable
especially if we did not state the risks.

As for the wider question, reparability, totally agree, even things like batteries in laptops are no no longer user replaceable,
but that is a very different question to the one outlined.


As for the even wider question raise, "I can do what ever I want as a free person, so long as XYZ",
well, thats a very long road to tread, what is XYZ, and way off topic I think ..
 

Irving

Joined Jan 30, 2016
1,020
As for the wider question, reparability, totally agree, even things like batteries in laptops are no no longer user replaceable,
but that is a very different question to the one outlined.
Ah, but is it? Forum rules already ban posts on "Transformer-less power supplies" yet they are a constituent of many consumer products - plug-in wireless door chimes for instance invariably have a simple series capacitor/resistor/diode/zener setup; I just repaired one of mine whose series 0.47uF capacitor had drifted off value far enough to reduce the current too low for it to chime - yet by forum rules I can't discuss that repair... so how long before someone decides that repairs to 'safety' equipment aren't acceptable... its a slippery slope to lobbying to prevent discussion of repair of equipment that 'only the manufacturer' is allowed to repair...
 
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