slept like a baby right at the waterline just
above #2 screw on Connie (CV-64) many, many
nights. Does that explain that bad filling in my tooth? :-)
At 05:50 AM 9/23/2009, Hernefjord Ingemar wrote:
>Jerry,
>
>slowly, a picture begins to form in my mind.
>When I was in the NAVY, I slept as a baby even
>at full spead (Destroyer), because the engine
>was twin steam turbines. Only vibration was a
>little from the propeller shaft. The
>last years, I have taken my family across the
>sea on a big RO-RO. THAT was a difference!
>Everything was vibrating. Coffee cups rotated on
>the plates, every chair had its own life, moved
>slowly like a snail, not to talk about the bed,
>that was hanging on the wall. I went through
>minimum and maximum nodes all the night,
>depending on difference in the rotation speed of
>the two main engines. You are
>right. Transportation on the sea means passing
>a vibration test. I am adding yours and
>Guenter's posting to the staff. In a few days, a
>group of technicians are being sent to fix the
>problems. I will do my best to get them understand.
>
>Thanks
>
>Inge
>
>
>-----Original Message-----
>From: TechNet [mailto:[log in to unmask]] On Behalf Of Jerry Dengler
>Sent: onsdag 23 september 2009 13:47
>To: [log in to unmask]
>Subject: Re: [TN] Knock, knock, knock on the heaven's door
>
>Hi Inge,
>
>We produced a product in the US for the US
>market that used a socket for a PLCC. This
>product's usage went up and the customer sent
>the production to China. At first all was
>well. After the production got to normal
>levels, suddenly they were getting a high level
>of out of box failures. These were all sent via
>ship. The earlier units were being air
>freighted in while the factory in China got up
>to speed. We found fretting at the socket to
>lead interface. We believe it is vibration from the ship that causes it.
>
>Recently the factory in China made 1000
>units. 500 were air freighted and 500 were sent
>via ship. We left the 500 units sent by air on
>the skid until the ocean units arrived. We then
>tested all 1000 units. 122 of the ocean units
>failed. None of the air units failed.
>
>Jerry
>
>-----Original Message-----
>From: TechNet [mailto:[log in to unmask]] On Behalf Of Hernefjord Ingemar
>Sent: Wednesday, September 23, 2009 5:59 AM
>To: [log in to unmask]
>Subject: Re: [TN] Knock, knock, knock on the heaven's door
>
>Hi Guenter,
>interesting. Very interesting. You got fretting
>issues at 28 Hz? Caused by floor vibration?
>Really? I've been involved in several fretting
>problems (aircrafts), but then we had much
>higher frequencies, maybe multiples of lower
>resonances. Our equipments were transported by
>ship to the other side of the planet, and it was
>then the problems started. I'll check how they
>were transported, time at sea etc.
>
>Thanks again
>
>/inge
>
>PS. What level of vibration?
>
>
>-----Original Message-----
>From: TechNet [mailto:[log in to unmask]] On Behalf Of Grossmann, Guenter
>Sent: onsdag 23 september 2009 09:41
>To: [log in to unmask]
>Subject: [TN] AW: [TN] Knock, knock, knock on the heaven's door
>
>Hi Inge
>
>Vibrations around? I just had recently a similar
>problem in an industrial environment. Failure
>analysis showed fretting on socket spring-
>contacts. When I made vibration measurements I
>found quite a spectrum of low level vibrations
>on the floor but a clear resonance at 28Hz in the rack.
>
>Best regards
>
>Guenter
>
>
>
> >-----Ursprüngliche Nachricht-----
> >Von: TechNet [mailto:[log in to unmask]] Im Auftrag von Inge
> >Gesendet: Dienstag, 22. September 2009 21:34
> >An: [log in to unmask]
> >Betreff: [TN] Knock, knock, knock on the heaven's door
> >
> >Well, not exactly that, but knock, knock, knock on a earthly board. One
> >customer needs fix a intermittent problem asap. 19 inch racks with
> >hundreds of PTH double sided boards, old technology, no BGAs, no QFMs
> >etc, but lots, lots of DIPs. The edge contact fingers have a very thick
> >and good gold over nickel, and the backplane connectors have really
> >stiff double tongues.
> >The
> >contact pressure/sq is extremly high and I think the contact spots are
> >really gastight once the board is plugged in. Now, they have electrical
> >issues, and they've found, that the signals are interrupted or coming
> >back when they knock on the boards. Someone is going to take a flight
> >the other day to fix the problem. The electricians believe, stubborn as
> >mules, that the only think needed, is to take out the boards and clean
> >the edge contact fingers with a solvent and that will fix it. Myself,
> >with quite many year's experience from connectors, I don't think that
> >is the problem, because when such robust contact springs wipe along the
> >contact fingers, they slide pretty deep into the gold and makes good
> >connection. Each spring has double contact ridges, so the risk that
> >some dirt should cause interrupts is minimal. There is more that talks
> >against their theory, namely, that the problem is still there after
> >plugging, deplugging more than once. I'm sure there is a solder joint
> >issue, or maybe a bond wire problem in the packages.
> >Logically, this later is more likely because you have thousands of
> >solder/bond joints vs, just some one hundred edge connector ditto. A
> >ratio like 10,000/100 per board. Without knowing all details, what is
> >your general experience between the index finger and the big toe?
> >
> >/Inge
> >
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