Digest for sci.electronics.repair@googlegroups.com - 8 updates in 5 topics

Jeff Liebermann <jeffl@cruzio.com>: Dec 15 08:49AM -0800

On Tue, 15 Dec 2015 11:48:05 +0000 (UTC), Bruce Esquibel
 
>http://www.pcliquidations.com/p15050-apc-back-ups-xs
 
I have one of those and can confirm that it eats batteries and doesn't
run very well. However, my total experience is with one unit, so
treat it as anecdotal.
 
Are you sure that's the UPS that the OP owns? It might also be this
model:
<http://www.kwaree.com/blog/2008/05/30/apc-back-ups-xs-1500/>
I have two of them that run without problems. I also have about 5
customers that have them. Batteries have been lasting about 5 years
and no lightning bolts or smog problems.
 
 
--
Jeff Liebermann jeffl@cruzio.com
150 Felker St #D http://www.LearnByDestroying.com
Santa Cruz CA 95060 http://802.11junk.com
Skype: JeffLiebermann AE6KS 831-336-2558
thekmanrocks@gmail.com: Dec 15 08:42AM -0800

Michael Terrell wrote: "
 
> How unAmerican that you do not smother your fries in ketchup! lol
 
 
I can't stand ketchup in or on anything, because of the vinegar in
it. Eat it if you want to, but keep that garbage away from me. It makes
me violently ill. "
 
Holy horse-feathers we're lighting that candle from
opposite ends: I positively DRINK the stuff, LOL!
"Ralph Mowery" <rmowery28146@earthlink.net>: Dec 15 11:09AM -0500

"Jeff Liebermann" <jeffl@cruzio.com> wrote in message
news:0r9v6b5fq4unaprjln8f3ugeshrpj0t83n@4ax.com...
> when warm, and not running when cold.
 
> I'll disclose what was really wrong after I fix it, probably next
> year.
 
Going to look bad when it is a bad power cable or socket.
 
Could be the capacitors. A number of years ago when the bad capacitors were
in many computers a friend had a computer in his basement that sometimes
came on and sometimes not. He left the cover off of it and would put a
light bulb next to the computer to heat it up. The computer wold come on
and work fine unless he shut it off , then he had to heat it up again with
the light bulb.
Tim R <timothy42b@aol.com>: Dec 15 06:16AM -0800

Most important, assume nothing. As soon as you think you know what is wrong, it is impossible not to ignore contrary evidence.
 
I work with some engineers who are good designers because they keep their brain fixed on the goal and work through every obstacle. They THINK they are also good troubleshooters but they are wrong, obstinately frustratingly wrong, for the same reason. They KNOW what is wrong too early, and nothing shakes their belief.
 
Second. When anybody tells you the symptoms, listen. When they tell you why, STOP! Don't listen. It will probably be theoretically impossible, and then you end up doubting the symptoms. Sorry but this is especially a problem with techs and mechanics. They observe correctly but theorize contrary to the laws of physics, so you need to stop listening when they get to that point.
John Robertson <spam@flippers.com>: Dec 15 07:37AM -0800

On 12/15/2015 4:17 AM, Mark Zacharias wrote:
> customers who have been on the internet.
 
> Another thread here, I see...
 
> Mark Z.
 
Capacitors?
 
<ducking>
 
I must confess we do replace almost all electrolytic caps that are more
than about 30 years old in our vintage game monitors and amplifiers
(video/pinball/jukebox) as this saves a tremendous amount of
troubleshooting time. It is true that perhaps 60% of the caps replaced
are fine, but the rest are marginal at best and make all sorts of errors
creep in that would take hours to find otherwise.
 
</ducking>
 
While we are in there we check resistors on
collectors/emitters/plates/cathodes as they often drift out of value.
However those we only change if off more than 10%
 
John :-#)#
 
--
(Please post followups or tech inquiries to the USENET newsgroup)
John's Jukes Ltd. 2343 Main St., Vancouver, BC, Canada V5T 3C9
(604)872-5757 or Fax 872-2010 (Pinballs, Jukes, Video Games)
www.flippers.com
"Old pinballers never die, they just flip out."
"Ralph Mowery" <rmowery28146@earthlink.net>: Dec 15 10:52AM -0500

"John Robertson" <spam@flippers.com> wrote in message
news:v72dnRqUANBaru3LnZ2dnUU7-V-dnZ2d@giganews.com...
> troubleshooting time. It is true that perhaps 60% of the caps replaced are
> fine, but the rest are marginal at best and make all sorts of errors creep
> in that would take hours to find otherwise.
 
It all depends on the cost and how much later down time you want to take a
chance on.
 
At work we had a 200 HP motor drive control that quit and we called in a
factory repair man. He determined that 2 large diodes ( arund 600 volt and
100 amp or so) were bad. AS this was a 3 phase unit , there were 3 diodes.
I told him to replace the 3 rd one as it may have had some stress on it and
may fail later. He said he would but it was $ 50 for the diode. I told
him that at what we were paying him and the ammount of production it would
cost that $ 50 was nothing worth even thinking about.
"Ralph Mowery" <rmowery28146@earthlink.net>: Dec 15 11:03AM -0500

"Ken" <Ken@invalid.com> wrote in message news:n4p0le$58i$1@dont-email.me...
> later." I cannot tell you how many problems I solved while doing that.
> Sometimes getting just getting away from the problem allows clearer
> thought.
 
That often works. If possiable after working on a problem for a while, as
someone else to take a look at it. Don't even tell him what you have done
or checked.
 
I found that it is beter for me when asked for help to not even listen to
what others have checked. It does pay to listen to see what parts they may
have changed out. Then check those parts to make sure they are good and
installed correctly.
 
I have done two things that rate as my worst boners. First was a problem
with a SCR temperature controler. Thought I had repaired it, but when
turning on the power it would blow a fuse. Did that 3 times and I just
could not understand it. The next fuse I installed, I checked it and it was
bad. Turned out when I checked the parts bin that half of the new ones were
bad.
 
Another one was when I replaced a part that came with about 20 feet of 5
wire cable of about # 20 wire. I used the old wire to pull the new wire
through the conduit. Some how I got distracted for a while and then when I
connected the wires, I had forgotten to cut off the old wire. That ment I
connected one end of the old wire back up and the other end was not
connected to anything. I asked someone else to see what it was that I had
done wrong as I knew it must be something simple that I over looked. He
took one look in the junction box and asked why there was so much wire in
it. Then found out what I had did wrong.
N_Cook <diverse@tcp.co.uk>: Dec 15 02:34PM

So assuming Blumlein 300Hz recording characteristic.
I'll feed a few uV from an audio sig gen parallel with the cartridge and
adjust treble and bass to try to get something like
3dB down at 300Hz , flat between 600Hz and 3KHz, +3dB broad hump between
3 KHz and 7KHz and as little as possible above 8KHz.
Whatever it graphs out as, record the details.
Try a couple of seconds recording at centre, mid and outer, to check for
enough but minimum stylus weight and antiskating , then review those
recordings before going for a full run on 3 recording media.
I've not set modified the deck yet, I'll time the revs when done, but
it should be 50.3 RPM assuming 50Hz mains
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