[1000mp] MP Erratic Turn on

Harold Mandel ka1xo at juno.com
Mon Jul 24 15:54:34 EDT 2006 

Dear Joel,

I am a Marconi Level-4, Cat.II central office installer
and your name seems mighty familiar.

I worked in New England and in upstate New York for some years
installing Marconi 1231's, etc.

  Hal Mandel צּ °¿°¬
 
-----Original Message-----
From: 1000mp-bounces at mailman.qth.net [mailto:1000mp-bounces at mailman.qth.net] On Behalf Of Joel Richey
Sent: Monday, July 24, 2006 3:03 PM
To: All about Yaesu 1000mp
Subject: Re: [1000mp] MP Erratic Turn on

Well put..W2DBO
Marconi Communications (Lorain Chargers) Retired..

73"s

Joel Richey
----- Original Message -----
From: "Harold Mandel" <ka1xo at juno.com>
To: "'Ken KW0A'" <kw0a at mindspring.com>; "'All about Yaesu 1000mp'"
<1000mp at mailman.qth.net>
Sent: Monday, July 24, 2006 7:15 AM
Subject: RE: [1000mp] MP Erratic Turn on


Dear Doctor Kreski,

>From experience with all sorts of a.c. powered semiconductor gear
including switching-type power supplies it is no small wonder that you
report this failure to me.

As an example, let's use the telephone industry, which employs low-voltage
D.C. supplies at many locations:

For years, D.C. (-48V), was generated by using motor-generator sets
whose output was connected to strings of flooded battery cells. The
offshoot from this was a set of wires connecting it to the various
appliances
needing D.C. to operate. The failure scenario was usually the brushes on the
commutators wore out and needed replacement. These devices, with
suitable cleaning and maintenance, ran continuously for twenty or thirty
years, night and day without breakdown. They were built to not break,
as was most of the telephone infrastructure.

Solid-state devices began making an appearance in the early 'Sixties.

The MG sets were found to have a waveform that had a bit of hash on the
signal from the rotating gear, and so these MG sets were replaced with
ferroresonant Class-A rectifiers. These devices used heavy iron and
also had capacitors as filters. The failure rate on these jumped up when it
was found
that the electrolytic filters were wearing out. The Mean Time Between
Failure on the
solid-state "ferros" was in the thousands of hours of operation.

Of course, with such a disastrous failure rate (!) research was conducted to
find
out why. Not only were the capacitors failing, but the rectifier junction
devices were, too, and
this was thought to be a function of the worn electrolytics, but after much
observation
it was discovered that high voltage pulses on the power lines were just
traveling through
the cabinets and appeared on the output lines. It took the advancement of
Hewlett-Packard's
fast oscilloscopes to see these.

Then in the cellular wireless world weight became an issue. Shelters could
not support
heavy Class-A units. Floors could not support 25,000 pound battery plants. A
decision
was made to migrate to switching power supplies and Valve-Regulated,
Lead-Acid (gel)
battery cells. While these batteries had the correct potential, they also
did not have the
same low impedance that flooded cells brought to the industry. This was a
factor
that further reduced the MTBF to the point now where at least thirty percent
of all
switching power supplies fail catastrophically within their first 1,000
hours of operation,
and the replacement modules are not expected to last very much longer
despite manufacturer's
warranties that proclaimed any different.

This then comes back to the Power Line Disturbances. These are caused by the
switching on and off of electrical appliances. These have always been there.
Refrigerators, light bulbs,
heating systems, etc., all make these pulses.

When semiconductor speeds were slower, these pulses could just go through
the power supplies with little effect. The low impedance battery plants
would absorb them. The switching equipment used mostly coils and
resistances, so no damage, or little damage would occur.

With microprocessor control, the effect of PLD's damaging equipment picked
right up. The faster the appliance processor, the more it was susceptible to
PLD pulses.

So now we have switcher supplies with no battery ballasts, with no front-end
protection,
connected to power lines that are as unconditioned now as they were one
hundred years ago.

I unplug everything when it's not in use. There is little more I can do
except revert to class-A
supplies with heavy electrolytic filtering. The lower the impedance, the
less chance a ten-thousand volt, one picosecond PLD pulse has of getting
through, but still, they do

Forgive the diatribe. It's a subject that torques me.

Hal
W4HBM



  Hal Mandel צּ °¿°¬

-----Original Message-----
From: 1000mp-bounces at mailman.qth.net [mailto:1000mp-bounces at mailman.qth.net]
On Behalf Of Ken KW0A
Sent: Sunday, July 23, 2006 5:16 PM
To: All about Yaesu 1000mp; 1000mp at mailman.qth.net
Subject: Re: [1000mp] MP Erratic Turn on

That course of events seems different from those most folks experience
wherein the unit never fails completely. My MP is also about '95 mfr.

Ken KW0A

-----Original Message-----
>From: nb1b at comcast.net
>Sent: Jul 23, 2006 4:39 PM
>To: 1000mp at mailman.qth.net
>Subject: [1000mp] MP Erratic Turn on
>
>Guys
>
>My MP exhibited the same problem, until it failed completely.
>
>The switching power supply stopped working.  It was intermittent for
awhile; it would work, then not work, then work, then work, then not work.
I could find no rhyme nor reason for it working or not working.
>
>Finally, the switching power supply failed completely.  I tried to find
someone to fix it, but everyone gave me the same answer- its more problem to
fix than its worth.  Still, a new one is $450, so I connected a DC supply
and its worked FB ever since.
>
>Hope I'm wrong, but that's what happened with mine.  BTW, I purchased it in
1995.
>
>Dennis NB1B
>______________________________________________________________
>1000mp mailing list
>Home: http://mailman.qth.net/mailman/listinfo/1000mp
>Help: http://mailman.qth.net/mmfaq.html
>Post: mailto:1000mp at mailman.qth.net


K. Kreski M.D., A.B.I.M.
KW0A  (EM48wx)
10240 Mackenzie Road
Affton, MO 63123-7301
U.S.A.

cell 314-578-1776
______________________________________________________________
1000mp mailing list
Home: http://mailman.qth.net/mailman/listinfo/1000mp
Help: http://mailman.qth.net/mmfaq.html
Post: mailto:1000mp at mailman.qth.net



______________________________________________________________
1000mp mailing list
Home: http://mailman.qth.net/mailman/listinfo/1000mp
Help: http://mailman.qth.net/mmfaq.html
Post: mailto:1000mp at mailman.qth.net


______________________________________________________________
1000mp mailing list
Home: http://mailman.qth.net/mailman/listinfo/1000mp
Help: http://mailman.qth.net/mmfaq.html
Post: mailto:1000mp at mailman.qth.net

More information about the 1000mp mailing list