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September 2009

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TechNet E-Mail Forum <[log in to unmask]>, Jerry Dengler <[log in to unmask]>
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Wed, 23 Sep 2009 13:11:09 -0400
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TechNet E-Mail Forum <[log in to unmask]>, Randall L Bock <[log in to unmask]>
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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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