Re: Valve amp longevity

On Mon, 20 Mar 2006 21:57:34 -0000, Steve at fivetrees
<steve@xxxxxxxxxxxxxxxxxxxxx> wrote:

FWIW, I agree - mostly. Point-to-point wiring vs PCB is an old, tired,
boring argument.

However, there is one small grain of truth there. With PCB
design/construction, there has sometimes been too much dependence on the
PCB/joints as a means of physical support, meaning:
- Heavy components need to be secured - not just by the soldered joints
- Connectors are stress points - connectors soldered to PCBs without
strain relief are *the* single most unreliable component

Absolutely, proper design and construction are more important than the
actual constsruction method chosen. One of the oldest pcb-based bit of
kit I own is a UHF tranceiver built around 1970. It spent the first 12
years of its life being abused in a fire engine and I've used it ever
since and it has _never_ had a failure of any sort. But that is
properly designed and built with thick PCBs and well secured components
with the boards interconnected by well secured harnesses.



One other point: back in the days when PTP was common, soldering was a very
carefully taught craft in industry. I remember DOI drawings of the various
kinds of joint (lay-on, wrap, etc) and their acceptable shapes. (Similarly,
a wireman was a skilled operator - some of the looms one saw [and still
occasionally does see] were works of art - wire sculptures, beautifully
done.) With PTP, one was expected to make a good mechanical joint *before*
soldering - i.e. it was strong.

My Racal receivers are built like that, but it costs money to do.
Racals cost as much as a good car!


--
Cheers,
Stan Barr stanb .at. dial .dot. pipex .dot. com
(Remove any digits from the addresses when mailing me.)

The future was never like this!
.

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