Vaillant ecoTEC plus 428 f27, f64 & CON error
- Thread starter dipz
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Since small caps are only a pound or so its hardly worth measuring them except for interest sake.
There is also another characteristic of caps which can affect circuit operation and that is the series AC resistance. But not quite so easy to measure. Usually high resistance is accompanied by a loss of capacitance.
There is also another characteristic of caps which can affect circuit operation and that is the series AC resistance. But not quite so easy to measure. Usually high resistance is accompanied by a loss of capacitance.
I am in the camp where I will measure the capacitance (if I have to) VERY carefully and see if it matches what is printed on the body. Price of the component has little bearing on it as measuring the capacitance only takes seconds while sourcing, even a capacitor costing pennies, and then changing is going to take considerably longer.
By AC resistance, Tony, I take it you mean capacitor reactance which is reciprocal of 2pifC. C is the only figure that will be the variable if capacitor goes belly up. Again, easily checked with a capacitor. I suspect the reactance is a smoke screen here as electrolytic capacitor would not be subjected to frequency component 'f'. By that I mean AC waveform not rectified AC waveform or raw DC waveform.
No, I very specifically mean the series resistance which is an important feature for caps used for smoothing.
ESR Defined
ESR is the sum of in-phase AC resistance. It includes resistance of the dielectric, plate material, electrolytic solution, and terminal leads at a particular frequency.
ESR acts like a resistor in series with a capacitor (thus the name Equivalent Series Resistance). This resistance often is the cause of failures in capacitor circuits.
These circuits look just fine on paper, but the hidden resistance causes failure due to heat buildup. To charge the dielectric material current needs to flow down the leads, through the lead plate junction, through the plates themselves - and even through the dielectric material.
Dielectric losses can be thought of as friction of aligning dipoles and appears as an increase (reduction of the rate of decrease) of the measured ESR as frequency increases. This increase is what makes the resistance vs freq line go flat above a certain frequency.
As the dielectric thickness increases so does the ESR. As the plate area increases, the ESR will go down if the plate thickness remains the same. To test a capacitor's ESR requires something other than a standard capacitor meter. While a capacitor value meter is a handy device, it will not detect capacitor failure modes that raise the ESR. As the years go by, more and more designs rely on low ESR capacitors to function properly. ESR-failed caps can present circuit symptoms that are difficult to diagnose.
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Tony, repairing boilers is a practical exercise
If I see a capacitor can that looked pumped up and rounded, I would change it if I had the same capacitor (make and model). If I meter a capacitor where the electrolyte had leaked, it being the component part that determines the capacitance of the component, I would change it again if I had the same brand and model
If I were the designer of a circuit, I would feel it to be appropriate then to look at characteristics of chosen capacitor, ESR being one such parameter.
Do I need to get to grips with ESR? No, the task is to get the boiler working- new pcb does that
If a capacitor looks suspect, do I rush to nearest Maplins for a replacement? No I don't, I replace the pcb
We are talking about practical field work here, not theoretical, or designing circuitry using spectrum analysers, oscilloscopes or lab equipment that would be beyond reach of almost every RGI
Note no googling done above
If I see a capacitor can that looked pumped up and rounded, I would change it if I had the same capacitor (make and model). If I meter a capacitor where the electrolyte had leaked, it being the component part that determines the capacitance of the component, I would change it again if I had the same brand and model
If I were the designer of a circuit, I would feel it to be appropriate then to look at characteristics of chosen capacitor, ESR being one such parameter.
Do I need to get to grips with ESR? No, the task is to get the boiler working- new pcb does that
If a capacitor looks suspect, do I rush to nearest Maplins for a replacement? No I don't, I replace the pcb
We are talking about practical field work here, not theoretical, or designing circuitry using spectrum analysers, oscilloscopes or lab equipment that would be beyond reach of almost every RGI
Note no googling done above
Yes, but if you must try repairing PCBs then you need to be aware of the last sentence of the bold part that I posted.
That a high ESR can present symptoms that may be difficult to diagnose only doing capacitance measurements.
That a high ESR can present symptoms that may be difficult to diagnose only doing capacitance measurements.
Hence, when reconditioning pcbs is often better to replace all the electrolytics at once rather than trying to measure and verify.
Having said that my 2003 DVD player seems to go a year before the next cap dies....but they are very thoughtful and the top vent pops giving a simple tell tale.
By the very questions asked the OP is not in any way competent to carry out pcb repairs. Many components also have secondary functions ie resistors also acting as fuses....and that may only be apparent from reading the original datasheet so an exact replacement is required to maintain safety.
Having said that my 2003 DVD player seems to go a year before the next cap dies....but they are very thoughtful and the top vent pops giving a simple tell tale.
By the very questions asked the OP is not in any way competent to carry out pcb repairs. Many components also have secondary functions ie resistors also acting as fuses....and that may only be apparent from reading the original datasheet so an exact replacement is required to maintain safety.
Gasguru, thanks for posting.
I read your posts regularly, needless to say you advice and information is always good and to the point.
Tony, do I repair pcb for a living? No.
Do I want to be lumbered with callbacks having repaired a pcb? No
Do I care if ESR is an issue? No, becuase I would be fitting a new pcb
If indeed I did carry out a repair on a pcb, it would be short term until a replacement could be fitted.
Need I say, ESR is NOT relevant to this thread
This is yet another term thrown in in similar faahion to 'not many engineers use heat sink compound', squashing pipes etc. When I was with BT, there were engineers who could talk a good fault but these same guys were useless at fixing actual faults. While I am not suggesting you talk a good fault, some of the stuff you post clearly is way off the mark- what has ESR to do with vaillant fault code.
I read your posts regularly, needless to say you advice and information is always good and to the point.
Tony, do I repair pcb for a living? No.
Do I want to be lumbered with callbacks having repaired a pcb? No
Do I care if ESR is an issue? No, becuase I would be fitting a new pcb
If indeed I did carry out a repair on a pcb, it would be short term until a replacement could be fitted.
Need I say, ESR is NOT relevant to this thread
This is yet another term thrown in in similar faahion to 'not many engineers use heat sink compound', squashing pipes etc. When I was with BT, there were engineers who could talk a good fault but these same guys were useless at fixing actual faults. While I am not suggesting you talk a good fault, some of the stuff you post clearly is way off the mark- what has ESR to do with vaillant fault code.
The ESR is totally relevant to DP's post on Thursday at 1150 where he says that he measures capacitance.
It is to demonstrate that just because a component may have the correct capacitance value, it may have a high ESR and consequently not function correctly in the circuit.
Electronics is no longer very simple.
Tony
It is to demonstrate that just because a component may have the correct capacitance value, it may have a high ESR and consequently not function correctly in the circuit.
Electronics is no longer very simple.
Tony
So you ARE saying a capacitor that is flat as a pancake for capacitance should not be changed for one similar valued one or capacitance measured to ascertain it is faulty.
Tell you what. I will present myself at a place of your choosing on Monday morning, two days from today
You can then demonstrate to me ESR on selected capacitors and how it effects circuit operation. Electronic circuits will be presented to you with actual components. You will then select high ESR value capacitors and low ESR caps too. We will document the results and post the results here. Rest assured it will be a thorough test using chips and discrete components to see the difference ESR makes in simple circuitry
I hope you take the challenge as I am keen to learn. I am in London at this moment in time so will avail myself.
By the way, you say ESR may effect circuit operation. You are hedging with that statement. You will get a chance to prove your statement
Tell you what. I will present myself at a place of your choosing on Monday morning, two days from today
You can then demonstrate to me ESR on selected capacitors and how it effects circuit operation. Electronic circuits will be presented to you with actual components. You will then select high ESR value capacitors and low ESR caps too. We will document the results and post the results here. Rest assured it will be a thorough test using chips and discrete components to see the difference ESR makes in simple circuitry
I hope you take the challenge as I am keen to learn. I am in London at this moment in time so will avail myself.
By the way, you say ESR may effect circuit operation. You are hedging with that statement. You will get a chance to prove your statement
Dan that is a very good invite. I am returning north on Monday around noon
I am in Eastcote quite often. Can certainly arrange a meeting if you are game.
There is a place close to son's place if you are up for it next time I come down. Will give you plenty notice.
Cannot stay away as wee man is 4 months old; every day brings a new trick from him.
I am in Eastcote quite often. Can certainly arrange a meeting if you are game.
There is a place close to son's place if you are up for it next time I come down. Will give you plenty notice.
Cannot stay away as wee man is 4 months old; every day brings a new trick from him.
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