Intermittent Faults - Preferred Lay Remedies

"Phil B" <[email protected]> wrote in message
news:[email protected]...
>
> "Brian A" <[email protected]> wrote in message
> news:[email protected]...
>> On Tue, 08 May 2007 08:35:28 GMT, DH <[email protected]> wrote:
>>
>>>News Reader wrote:
>>>> Hi,
>>>>
>>>> Can I get peoples opinions on and suggestions of lay / informal
>>>> remedies to
>>>> intermittent faults.
>>>>
>>>> My /one suggestion is "bouncing", such as with a soft surface - e.g. a
>>>> bed.
>>>> "Grasp device at one end, 'bounce' onto and off soft surface. Plug in
>>>> and
>>>> try again".
>>>>
>>>> Thanks.
>>>>
>>>>
>>>> Best wishes,
>>>>
>>>>
>>>>
>>>> News Reader
>>>>
>>>>
>>>
>>>Hit it with a "virtual" stick, much better than threast.
>>>
>>>DH
>> Intermiitent faults can often be due to soldered joint or component
>> problems.
>> These often depend on temperature. The particular method(s) I have
>> used have depended on the fault type, these are:-
>> 1. Tap printed circuit boards, in various places, with the non-metalic
>> part of a screwdriver. This method can be used, gently, on thermionic
>> devices, such as on the neck of a CRT, if that is suspected.
>> 2. If intermittent noise, try squirting 'freezer' aerosol on
>> individual components, that you have homed in on, by studying the
>> circuit/making measurements - i.e. standard fault finding techniques.
>> 3. Use a hairdryer on suspect areas, to raise the temperature, if you
>> suspect a temperature driven fault.
>> 4.Put it on 'soak' - i.e. give it time, get on with something else but
>> kep an eye on the performance of the device under test.
>>
>> If the fault fails to materialise then, at least, clean up the
>> circuit boards and make sure any switches etc.are cleaned, where
>> appropriate. Hope this helps!
>>
>
> All those are good.
> I worked in a mainframe design lab in the 1960s using TTL and wrapped
> backplane joints. Other techniques we used were:
> - look for dry joints - any not shiny and with a dusty appearance - and
> resolder them.
> - wiggle all the wrapped wiring with a stiff brush,
> - alter the supply voltage (but within limits). TTL had a tolerance of
> 4.75 to 5.25 volts but I liked to weed out anything which failed if I took
> it down to 4.3 volts.
> - flex or twist the printed circuit boards slightly - a real killer for
> intermittents but take care of high voltages and static sensitive stuff.
> - rattle all the boards. After visiting and fixing one troublesome
> system my boss asked me whether I'd rattled the boards. I had, with a
> plastic connector cover, but I was reprimanded for not using a hammer.
> On a subsequent occasion I was again reprimanded for not physically
> breaking any boards with the said hammer!!
> Not sure that's particularly good if you want to rely on a warranty
> though.
>
> Hope that helps.
>
> Phil
>
>> Remove 'no_spam_' from email address.
>
>
>
>


Hi,

On a slightly more serious note... most of that certainly sounds very good.

Not so sure about the employers fervent hammer fixation... but otherwise all
sounds good .

I think with more shock sensitive equipment, or anything you wish to shock
but without such direct impact or abrasive contact, the bouncing method is
quite a good intermediary step. Obviously, if that fails, you can always
escalate to the higher impact effect of knocking into or "bouncing" or
dropping onto a hard surface.

Of course, the reality is that the proper approach, is to use test equipment
and proper fault testing methods.

However, that is not always possible, and equally, you may be aware of the
faulty component and just be trying to prolong its operation. Hard drives
interestingly whilst hating high g shock, often enough seem to appreciate or
rejuvenate on a middling motion effect (bouncing, etc.).

All good fun.


Best wishes,




News Reader

---

› See More: Intermittent Faults - Preferred Lay Remedies

"Dr Teeth" <[email protected]> wrote in message
news:[email protected]...
>I was just thinking how wonderful life was, when "News Reader"
> <[email protected]> opened his gob and said:
>
>>Can I get peoples opinions on and suggestions of lay / informal remedies
>>to
>>intermittent faults.
>
> Bang your head against the wall and stick your tongue in a mains
> socket until the problem does not recur, or becomes permanent (i.e.
> non-intermittent).
>
> --
> Cheers,
>
> Guy
>
> ** Stress - the condition brought about by having to
> ** resist the temptation to beat the living daylights
> ** out of someone who richly deserves it.


Hi,


Hmmm.... not sure if I have totally got this one understood correctly... but
it sounds good


Best wishes,



News Reader

On Tue, 8 May 2007, News Reader wrote:

>
> "Dr Teeth" <[email protected]> wrote in message
> news:[email protected]...
>>I was just thinking how wonderful life was, when "News Reader"
>> <[email protected]> opened his gob and said:
>>
>>>Can I get peoples opinions on and suggestions of lay / informal
>>>remedies to intermittent faults.
>>
>> Bang your head against the wall and stick your tongue in a mains
>> socket until the problem does not recur, or becomes permanent (i.e.
>> non-intermittent).
>>
>
> Hmmm.... not sure if I have totally got this one understood
> correctly... but it sounds good
>
>

It may sound good, but it will taste out of this world

Robert
--
La grenouille songe..dans son château d'eau
Links and things http://rmstar.blogspot.com/

I was just thinking how wonderful life was, when "News Reader"
<[email protected]> opened his gob and said:

>Can I get peoples opinions on and suggestions of lay / informal remedies to
>intermittent faults.

Bang your head against the wall and stick your tongue in a mains
socket until the problem does not recur, or becomes permanent (i.e.
non-intermittent).

--
Cheers,

Guy

** Stress - the condition brought about by having to
** resist the temptation to beat the living daylights
** out of someone who richly deserves it.

In message <[email protected]>, M. J. Powell
<[email protected]> writes

>If you replaced faulty equipment then the new equipment showed the same
>fault and the old gear was perfectly serviceable.
>

I had an old electric drill once. It started to become intermittent. I
took it to pieces, checked the mains lead, but couldn't find anything
wrong. But still the fault persisted, so I bought a new drill.

The new drill exhibited exactly the same intermittent operation. I then
decided to look at the mains extension cable ....:-))

--
Ian

"M. J. Powell" <[email protected]> wrote in message
news:[email protected]...
> In message <[email protected]>, Graham <[email protected]> writes
>>
>>"News Reader" <[email protected]> wrote in message
>>news:[email protected]...
>>>
>>> Hi,
>>>
>>> Can I get peoples opinions on and suggestions of lay / informal remedies
>>> to intermittent faults.
>>>
>>> My /one suggestion is "bouncing", such as with a soft surface - e.g. a
>>> bed. "Grasp device at one end, 'bounce' onto and off soft surface. Plug
>>> in
>>> and try again".
>>>
>>
>>In the early '90s we were supplying BBC model B's to Pharmacies.
>>The PSU suffered from dry-joints and the official trouble-shooting
>>guide said something like this.
>>
>>"If the computer fails to start up, lift up the entire machine to a height
>>of four inches above the bench, and let go"
>
> The GPO Pulse & Bar generator had, in the manual, a sentence which said
> "It is quite possible that every component will test within spec but the
> equipment fail to work."
>
> And no further advice.
>
> Mike
> --
> M.J.Powell

Are they saying that there might just be some tolerancing problems in the
design? The sort of problem you get is if this circuit is at the fast end
of its spec, that one is at the slow end and this resistance is a bit high
then X fails to happen. Very difficult to anticipate all the most unlikely
situations and avoid them with complex systems.

Phil

"Robert Marshall" <[email protected]> wrote in message
news:[email protected]...
> On Tue, 8 May 2007, News Reader wrote:
>
>>
>> "Dr Teeth" <[email protected]> wrote in message
>> news:[email protected]...
>>>I was just thinking how wonderful life was, when "News Reader"
>>> <[email protected]> opened his gob and said:
>>>
>>>>Can I get peoples opinions on and suggestions of lay / informal
>>>>remedies to intermittent faults.
>>>
>>> Bang your head against the wall and stick your tongue in a mains
>>> socket until the problem does not recur, or becomes permanent (i.e.
>>> non-intermittent).
>>>
>>
>> Hmmm.... not sure if I have totally got this one understood
>> correctly... but it sounds good
>>
>>
>
> It may sound good, but it will taste out of this world
>
> Robert
> --
> La grenouille songe..dans son château d'eau
> Links and things http://rmstar.blogspot.com/



Emmm... hemmm... armmmm..emmmm....

.... ZZZZ BANG XXXXZZZZ XXXZZZZZZ ...

In message <[email protected]>, ian <[email protected]> writes
>In message <[email protected]>, M. J. Powell
><[email protected]> writes
>
>>If you replaced faulty equipment then the new equipment showed the
>>same fault and the old gear was perfectly serviceable.
>>
>
>I had an old electric drill once. It started to become intermittent. I
>took it to pieces, checked the mains lead, but couldn't find anything
>wrong. But still the fault persisted, so I bought a new drill.
>
>The new drill exhibited exactly the same intermittent operation. I then
>decided to look at the mains extension cable ....:-))

HeHe!

Mike
--
M.J.Powell

In message <[email protected]>, Phil B
<[email protected]> writes
>
>"M. J. Powell" <[email protected]> wrote in message
>news:[email protected]...
>> In message <[email protected]>, Graham <[email protected]> writes
>>>
>>>"News Reader" <[email protected]> wrote in message
>>>news:[email protected]...
>>>>
>>>> Hi,
>>>>
>>>> Can I get peoples opinions on and suggestions of lay / informal remedies
>>>> to intermittent faults.
>>>>
>>>> My /one suggestion is "bouncing", such as with a soft surface - e.g. a
>>>> bed. "Grasp device at one end, 'bounce' onto and off soft surface. Plug
>>>> in
>>>> and try again".
>>>>
>>>
>>>In the early '90s we were supplying BBC model B's to Pharmacies.
>>>The PSU suffered from dry-joints and the official trouble-shooting
>>>guide said something like this.
>>>
>>>"If the computer fails to start up, lift up the entire machine to a height
>>>of four inches above the bench, and let go"
>>
>> The GPO Pulse & Bar generator had, in the manual, a sentence which said
>> "It is quite possible that every component will test within spec but the
>> equipment fail to work."
>>
>> And no further advice.
>>
>> Mike
>> --
>> M.J.Powell
>
>Are they saying that there might just be some tolerancing problems in the
>design? The sort of problem you get is if this circuit is at the fast end
>of its spec, that one is at the slow end and this resistance is a bit high
>then X fails to happen. Very difficult to anticipate all the most unlikely
>situations and avoid them with complex systems.

Well, it was a 405-line P & B Generator, hardly cutting edge technology
in those days, 1958.

Mike
--
M.J.Powell

On Thu, 10 May 2007 23:05:34 +0100, M. J. Powell wrote:

> In message <[email protected]>, ian <[email protected]> writes
>>In message <[email protected]>, M. J. Powell
>><[email protected]> writes
>>
>>>If you replaced faulty equipment then the new equipment showed the
>>>same fault and the old gear was perfectly serviceable.
>>>
>>
>>I had an old electric drill once. It started to become intermittent. I
>>took it to pieces, checked the mains lead, but couldn't find anything
>>wrong. But still the fault persisted, so I bought a new drill.
>>
>>The new drill exhibited exactly the same intermittent operation. I then
>>decided to look at the mains extension cable ....:-))
>
> HeHe!
>
Basic rule: check the fuel before stripping the engine!


--
Peter.
If you can do it today, you didn't put off enough yesterday.

>
> All those are good.
> I worked in a mainframe design lab in the 1960s using TTL and wrapped
> backplane joints. Other techniques we used were:
> - look for dry joints - any not shiny and with a dusty appearance - and
> resolder them.
> - wiggle all the wrapped wiring with a stiff brush,
> - alter the supply voltage (but within limits). TTL had a tolerance of
> 4.75 to 5.25 volts but I liked to weed out anything which failed if I took
> it down to 4.3 volts.
> - flex or twist the printed circuit boards slightly - a real killer for
> intermittents but take care of high voltages and static sensitive stuff.
> - rattle all the boards. After visiting and fixing one troublesome
> system my boss asked me whether I'd rattled the boards. I had, with a
> plastic connector cover, but I was reprimanded for not using a hammer.
> On a subsequent occasion I was again reprimanded for not physically
> breaking any boards with the said hammer!!
> Not sure that's particularly good if you want to rely on a warranty
> though.
>
> Hope that helps.
>
> Phil
>
I found once or twice that replacing the board that was glowing worked
wonders. Another time, removing a dozen or so paper clips, which had been
fired around the room from lazzy bands, by the bored operators, also seemed
to help. Or, reducing the height of the flood water.

Allan