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Author Topic: Why are steel supports still being used on circuit board?  (Read 2248 times)

Offline syhprum

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When TV manufactures in the early sixties started to use printed circuits one frequent source of failiure was the use of tinned steel support structures to link parts of the board at ground potential.
one would think some lessons would have been learnt over the last fifty years but no, I have just had mysterious problems with a TV dongle and upon opening it up found that the same misguided technique had been used.
« Last Edit: 28/01/2012 09:28:01 by chris »


 

Offline CliffordK

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Re: Bad circuit board design
« Reply #1 on: 11/01/2012 19:59:48 »
Hmmm,
I think computers use ordinary computer screws to connect the motherboard to the chassis, often with a little solder circle where the screws go.  Although, I believe that the computer derives all of its power through wire connections, so that the chassis ground is just redundant.

I'll tell you one thing they improved.
Hard drives used to have a squarish board that went right in front of the screw holes. 
If you put in a 1/4" mounting screw, it would smash into the circuit board, and your hard drive would never work again.
There is a much bigger gap around all the screws now.  Some lessons have been learned!!!
 

Offline syhprum

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Re: Bad circuit board design
« Reply #2 on: 11/01/2012 20:23:31 »
If you have two identical hard drives you can interchange the electronics and at least recover the data.
 

Offline CliffordK

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Re: Bad circuit board design
« Reply #3 on: 11/01/2012 21:12:13 »
If you have two identical hard drives you can interchange the electronics and at least recover the data.
True.
But, I think that was back in the MFM days...
So...  perhaps recovery now wouldn't be as easy as one might imagine.

There are a lot of piss-poor designs in this world that makes one just have to roll one's eyes.  For example, the VWs from the 80's have their taillights built with two parts glued together with an inaccessible lap-joint electrical contact in the middle with contacts that can corrode over time.

Chevy Pickups from about 10 years ago use a light-socket with a printed circuit board.  I forgot the issue, but the boards are good for about a year or so before going bad.

Not to mention the Dodge Cummins engines with a part appropriately called the "Killer Dowel Pin" (I haven't seen this one myself, but I've heard about it).
 

Offline syhprum

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Re: Bad circuit board design
« Reply #4 on: 26/01/2012 18:02:37 »
Clifford
With your mishap with the HDD you where in Illustrious company, I was browsing thru weather satellite data and stumbled on a 90 page report as to how they lost a newly launched NOAA13.
Apparently the power supply was built in such a way that it was a disaster waiting to happen the main output from the solar array rendered the whole PSU chassis live and it was seperated from the grounded body of the satellite by about 2mm of isulation with bolts holding relays etc poking into this isulation.
Lowly technicians had mentioned this but it is rather like nurses trying to advise doctors !

http://www.nasa.gov/home/hqnews/1994/94-157.txt 
By the time the ground controllers had worked out what had happened the batteries had run out and no communication was possible.
 

Offline SeanB

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Re: Bad circuit board design
« Reply #5 on: 27/01/2012 18:25:00 »
I have done HDD recovery using a donor board. Needs same model, and a firmware version that is identical or only a few steps away from the original. Worked well enough to copy the data onto another drive. Of course depends on the fault being the original drive is electrically faulty, which is nowdays more the case, as lead free solder is less reliable.
 

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Re: Bad circuit board design
« Reply #5 on: 27/01/2012 18:25:00 »

 

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