On 2/26/2011 5:38 PM, Sean Breheny wrote:
> Hi all,
>
> I was recently looking inside a late 1990s LeCroy scope and was
> impressed by the quality of construction. One thing really surprised
> me, though: all of the thru-hole electrolytic capacitors (radial type)
> were mounted about 1/8th inch above the PCB surface, rather than flush
> with the PCB. They were also bent over at random angles and not
> secured with any glue or RTV cement. It did not seem to be due to
> sloppy assembly because the size of the gap between the bottom of the
> caps and the PCB surface was quite consistent. Any ideas on why it
> would have been assembled this way? Even more importantly, any ideas
> on why  they did this without adding some type of material to secure
> the caps against vibration?
>
> Thanks,
>
> Sean

As noted by Bob, the lab environment is benign.  But pulling the parts=20
down tight to the pcb and then soldering can cause residual stress that=20
may break leads later.  So back in that era, they sometimes used spacers=20
on the leads of through-hole parts that subsequently dissolved in wash=20
water leaving the parts with a "service loop" in their leads.
--=20
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