Altair-what do I do first

From: Ross Archer <dogbert_at_mindless.com>
Date: Tue Oct 1 01:37:22 2002

Bob Shannon wrote:

> Thanks for catching my typo Joe. The MTBF (mean time between
> failures) is greatly REDUCED by unsoldering chips, often very
> dramatically so.


Hmm, I never even thought of this one before.
Yet another general argument for sockets. :)

I would think if you had an adjustable DC supply,
you could gradually ramp up the voltage on the unregulated
input and watch the output with a voltmeter. If it ever got
to 5.25 volts, you'd not want to ramp any higher and replace
the regulator.

That wouldn't help with re-forming caps though. Maybe
you'd start at the output of the regulator and work up from
a very low voltage? Or would undervoltage hurt some
components due to a mysterious process I'm not aware of?

-- Ross


>
>
> Ever notice the soldering specifications for TTL devices, like 300
> degrees C for not more than 10 seconds? This limitation is given for
> the parts to meet their rated MTBF, not because 300 degrees C for 11
> seconds will destroy the parts right away.
>
> Resolder the parts, and you may be throwing away well over half their
> service life. Clearly not a professional way to restore a machine.
> For some repairs, we have no other option, but melting solder is a
> last resort.
>
>
> Joe wrote:
>
>> At 10:38 PM 9/28/02 -0400, you wrote:
>>
>>
>>> If you think this does the least dammage, your grossly in error. As
>>> a test engineer, I can direct you to any number
>>> of volumes that will show you the dramatic increase in MTBF
>>>
>>
>> I think you mean dramatic DECREASE in MTBF. But I doubt many
>> people on this list even truely understand what MTBF is. I worked in
>> reliablility, logisitics and maintainablity so I'm prpobably one of
>> the few that would catch this.
>>
>> Joe
>>
>>
>>
>>
>>
>> for
>>
>>> resoldered parts. This is known, for-sure dammage, not some risk of
>>> dammage from a theoretical regulator failure.
>>>
>>> Care to defend this position?
>>>
>>>
>>>
>>>
>>>
>>>
>>>
>>>
>>>
>>
>>
>>
>
>
>
>
Received on Tue Oct 01 2002 - 01:37:22 BST