30 Jan
2009
30 Jan
'09
11:47 a.m.
On 30 Jan 2009 at 18:52, Tony Duell wrote:
The design _is_ something of a black art (in
particular the design of the
transformer -- the exact characteristics of that are critical to the
design). But repairing an SMPSU that has worked (and in th case of a DEC
Q-bus box, has been made many time,s and has worked well for years in
general) is a lot easier. You know the basic deisgn ins sound, you know
that particular transformer can work in that circuit, and so on.
While repair is interesting in its own right, it's the design that
really shows the mind (or lack thereof) of the engineer. For
example, it never occurred to me that putting an EMI line filter in
front of a SMPSU, while it may not disable, may compromise its
operation.
How many engineers have simply spec-ed an off-the-shelf PSU and stuck
it after one of those dandy little fuse-receptacle-power-switch-EMI
filter boxes without thinking to ask the PSU manufacturer if it was
advisable to do so? It certainly wouldn't have occurred to me.
Cheers,
Chuck