Headers problems

ANIRUDH VIJ ee05b077 at smail.iitm.ac.in
Sat Jun 16 09:41:06 PDT 2007


""""""""
Unless you know the circuit type (LC, RC, ...), its expected input and 
output, you are risking havoc by changing the value of *any* of the 
components in the circuit. IIRC, by changing the the capacitor to a 
higher voltage rating, you have altered (possibly) at least two things 
(assuming the circuit is more than a simple power conditioning circuit) 
that may be critical. 
"""""
The critical thing here is "value of component",not the voltage rating.I completely agree that 
changing the capacitors's value from 2200uf to something else may have caused havoc,but 
increasiing its voltage rating can only be a good thing.It only means that the chances of a capacitor 
exploding are lesser :)
If i correctly understood the previous post,the voltage rating increased while the value remained the 
same,so the capacitor itself should not be the source of the problem.

On Sat, 16 Jun 2007 10:43:00 -0400, Wit wrote
> Tijnema wrote:
> > On 6/12/07, Wit <WitlessIdiot at triad.rr.com> wrote:
> >   
> >> Tijnema wrote:
> >>     
> >>> <snip>
> >>>
> 
> >> I also become increasingly concerned with the mention of the capacitors
> >> and repair you did (IIRC?). Both would seem a "most likely" culprit,
> >> based on all the other things discussed. Putting the CPU in another mobo
> >> and running similar tests should confirm if it is related to CPU or
> >> something else in the system.
> >>     
> >
> > Just took my soldering iron and replaced the capacitor with replacer.
> > I can't test the CPU in another mobo, or test another CPU in the
> > current mobo as I don't have another PC with Socket A...
> > But, you hit a good point here, I touched my replaced capacitor while
> > the system just rebooted, and it was way too hot... I guess it was
> > around 60-70 degrees celcius. The original capacitor was a 10V 2200uF,
> > I replaced it with a 16V 2200uF capacitor, nothing wrong with right?
> >
> 
> I'll have to boot up my LFS later and see what else I did to get the 
> thermal stuff going. I do want to address the capacitor here.
> 
> Remember that I'm no electronics guru. I suggest you google or hit 
> some appropriate lists regarding this. But from my small exposure to 
> electronics ...
> 
> Capacitors are rated for storage capacity (picofarads, usually) at a 
> given voltage. If a given voltage is applied, maximum charge will be 
> achieved *in a given time-frame*. As with any electronic component, 
> there are internal *resistances* that affect timing, capacity, etc. 
> These are usually resistance, impedance, etc. Capacitors are used 
> for many things. Power conditioning, oscillation circuits, etc. 
> These are almost always in conjunction with other types of 
> components, such as coils (choke, voice, ...) and resistors. The 
> *properties* of all these components are considered in the circuit 
> design and are *coordinated* to produce the desired characteristics 
> in the output of the circuit with the expected input characteristics.
> 
> Unless you know the circuit type (LC, RC, ...), its expected input 
> and output, you are risking havoc by changing the value of *any* of 
> the components in the circuit. IIRC, by changing the the capacitor 
> to a higher voltage rating, you have altered (possibly) at least two 
> things 
> (assuming the circuit is more than a simple power conditioning 
> circuit) that may be critical.
> 
> That capacitor now takes longer than expected to reach its maximum 
> charge (assuming that the time alloted even allows it to do so - it 
> may in fact never achieve its maximum) and, as mentioned, the 
> maximum charge actually achieved.
> 
> Also, an important function of a capacitor is to discharge. The time 
> required and rate of that discharge are important to the proper 
> function of the circuit. If the capacitor is discharging into a 
> lower/higher voltage circuit than expected, its rate and degree of 
> dissipation of charge will vary from what is expected in the circuit 
> design. In a timing circuit, this would alter timings. In a 
> conditioning circuit, this would affect the degree and timing of 
> power fluctuations experienced in the output of the circuit.
> 
> As a side note, LC circuits can also be used (IIRC) to suppress RF 
> interference that may be experienced in the design. Altering the 
> value of the capacitor(s) will affect the RF frequency range that is 
> effectively suppressed.
> 
> So, I say don't change values of components unless you are 
> intimately acquainted with the overall design of the unit and the 
> specific circuits.
> 
> Last, electronic components have *tolerances*. These are typically 
> +/- percentages. These are specifications of manufacturing variances 
> allowed to meet the circuit design needs. When replacing components, 
> you must be sure that the tolerances of the new component meet or 
> exceed the design requirements. It would also be useful if you know 
> a lot more about this stuff than I know.
> 
> Again, pure amateur here who is remembering things learned from 
> curiosity many decades in the past. A local guru and google/lists 
> would be your best avenue for further investigation about the 
> reliability or your setup.
> 
> > <snip>
> >
> 
> >>> Tomorrow I will try the system with a  Asus 350W PSU, which now runs
> >>> an AMD X2 4400+ with 2 HDDs and a GeForce 7600GT..., should be enough
> >>> for my old system :)
> >>>
> >>>       
> >> Results?
> >> --
> >> Wit
> >>     
> >
> > No luck either...
> >
> 
> Sorry to hear that. I would lean heavily toward getting the 
> components you have repaired/replaced back to original equivalents 
> before spending time on other things. It may be that those non-
> equivalent parts are causing symptoms that we on the list normally 
> see with overheating CPU and/or bad components, like CPU, memory,
>  weak power, etc.
> 
> And, briefly, be assured that certain specific functions that are 
> intensive, like building kernel, glibc, etc. *do* stress many 
> specific system components and expose *weaknesses* in the system. A 
> good example is building (glibc IIRC) that could only be completed 
> in multiple passes because random "crashes" would occur during this 
> process. Fortunately, the make system can restart at appropriate 
> places and continue on. In my case, this was on an excellent PC-
> CHIPS M-571 mobo. Once I increased the capacity of the HSF and added 
> another case fan (I don't think this one actually helped the 
> specific problem), crashes stopped.
> 
> Again, the previous is from memory. Maybe it was not glibc.
> 
> I hope this is not useless drivel.
> 
> --
> Wit
> 
> -- 
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--
Anirudh Vij
Undergraduate Student
Electrical Engineering Department
IIT Madras.





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