Headers problems

Wit WitlessIdiot at triad.rr.com
Sat Jun 16 07:43:00 PDT 2007


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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