from the movies I can picture that...
-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of Jerry Dengler
Sent: Wednesday, September 23, 2009 1:06 PM
To: [log in to unmask]
Subject: Re: [TN] Knock, knock, knock on the heaven's door
I think sleeping on the USS Cincinnati (SSN-693) was the best. No wave action to interrupt the gently vibrations on the screw. Just had to watch out when they were training new helmsmen/planesmen they would take the submarine to high angles 30 degrees or so. Since most bunks were for/aft direction you would end up standing on your head.
Jerry
-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of Dwight Mattix
Sent: Wednesday, September 23, 2009 11:28 AM
To: [log in to unmask]
Subject: Re: [TN] Knock, knock, knock on the heaven's door
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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