Which device is causing this?

[et...@whidbey.com]

I have a computer with a flaky power supply. If the computer is
unplugged for a while it will not turn on after it has been plugged in
again until sometime has passed. About 10 minutes at room tepmerature.
A couple days ago the power lines to my house came down along with the
snow. The outside temp was in the low twenties. By the time power had
been re-established the office temp was only about 25 degrees. In
order to get the computer to start I had to direct the hot air from a
blow drier into the back of the computer. After a few minutes it
started up. So what device fails when cold?
Eric

[Jeff Liebermann]

Bulging electrolytic capacitors in the power supply.
http://www.badcaps.net
http://en.wikipedia.org/wiki/Capacitor_plague
http://802.11junk.com/jeffl/pics/repair/slides/bad-caps.html

--
Jeff Liebermann je...@cruzio.com
150 Felker St #D http://www.LearnByDestroying.com
Santa Cruz CA 95060 http://802.11junk.com
Skype: JeffLiebermann AE6KS 831-336-2558

[Sjouke Burry]

A degraded, old capacitor.
Those, when cold, have a high serial resistor,
and wont work properly.
When you heat them, the resistor value will go down quite a lot,
and things start working.
A very common cause of equipment failure, very dependent on
temperature.

[et...@whidbey.com]

Thanks Jeff and Sjouke. Now I know what to look for.
Eric

[Maynard A. Philbrook Jr.]

In article <6tjp7a931epgpifkh...@4ax.com>,
et...@whidbey.com says...

Try replacing the Power Supply!

Jamie

[et...@whidbey.com]

You did notice that this is an electronics REPAIR group, right?
Eric

[Michael Black]

And the poster did a good job of conveying symptoms, but said nothing
about looking inside the power supply.

That's a good indicator that they are't capable of component level repair,
so "replace the power supply" was a suitable answer in this case.

One always has to read beyond the stated question, to evaluate what
capability the poster has.

Michael

[Maynard A. Philbrook Jr.]

In article <dv718ade9jmos0oe8...@4ax.com>,
et...@whidbey.com says...

Sure did and if you knew what you were talking about you would know
that cost of labor investigating internals of a power supply over simply
just replacing it has a broad dollar value. Labor is expensive but the
cost of a replacement supply or just simply plugging in a test unit is
much cheaper

Next time, think , think, and think again before opening the trap.

Jamie

[et...@whidbey.com]

On Thu, 4 Dec 2014 18:45:12 -0500, "Maynard A. Philbrook Jr."

Since I'm going to repair it I have decided the labor is worth it. I
suppose I should have said that I was going to repair this power
supply. I did not say if I had looked in the power supply. I should
have because I did. But it seems like I did not look closely enough.
This weekend I'll take another look and hopefully find a bulging cap
that I can replace.
Eric

[stra...@yahoo.com]

You can buy a 500 W power factor corrected supply from Newegg for $40 and THEN get a $15 rebate. Buying good caps to redo your old supply will run $5-$10 and we haven't added the value of your time. Add another $5-$10 for a new cooling fan and you see how they are disposable.

You must be young enough that the 'satisfaction' of repairing it has value but you'll get over it. Personally I replace power supplies but replace caps on motherboards to get going again. Repair the things that are hard to replace.

Also there are nasty Voltages in the power supply but none on the mobo.

G²

[Tim R]

On Friday, December 5, 2014 12:07:45 AM UTC-5, stra...@yahoo.com wrote:
> You must be young enough that the 'satisfaction' of repairing it has value but you'll get over it. Personally I replace power supplies but replace caps on motherboards to get going again. Repair the things that are hard to replace.
>
> Also there are nasty Voltages in the power supply but none on the mobo.
>
> G²

There is some satisfaction in the learning process itself though.

I hadn't realized at first but now obviously this is a PC but not a laptop. So I don't know if my observation applies here at all. But given our history with the kids's school laptops, the power supply and the power jack seem to be weak links. We've gone through a number of replacement wallwarts or equivalent, and have had several where the power jack connection eventually fails.

I guess there's no point making them bulletproof when the PC is obsolete in a few years, but it sure is annoying to have an otherwise workable machine unusable because you can't power it up.

[et...@whidbey.com]

I can also just grab a cap out of my box of caps. I guess 58 is
probably young enough 'cause I'm still getting satisfaction from
fixing and building things. I think by the time I get over it I'll be
ashes.
Cheers,
Eric

[Michael Black]

But you missed the point. You didn't do any analysis, it's not clear
whether you actually understand even the basics of that power supply, you
came here wanting a remote diagnosis, so you could "repair" it by changing
the part specified. You didn't even use a specific subject header, you
used an extremely vague one.

Repair isn't just about changing parts, it's about figuring out what's
wrong. A lot of places do "repair" by changing motherboards or power
supplies, 21 years ago I got a Mac Plus because it had a problem and Apple
wanted hundreds of dollars to change the video board. I opened it up,
figure out what was wrong, and fixed the problem, just a bad connector
that wasn't making proper contact. I had the skill, the Apple people had
the "skill" to change the board, nothing more. So you could have made
this 'repair" by changing the power supply, and since you require
specifics from the crowd, you aren't really making a repair here, just
plugging in components, just a finer gradation than plugging in a new
power supply.

I've seen that "badcaps" site, lots of people with a little bit of
information, but they get lost if they fall off the path mapped out for
them. Or, they take that bit of knowledge about "bad caps" and think it
extends to all capacitors, when it doesn't. That's the future of the
world, the internet future where people think they are fixing things
because they can follow detailed instructions that someone else has
written down for them.


Michael

[et...@whidbey.com]

Well Michael, I guess you're right. I don't know a lot about
electronics but I can diagnose stuff. I tried to keep the subject
header short which is why it was ambiguous. You are also correct that
repair can be just unplugging (or unsoldering) a component or a whol
system of parts, like the complete power supply. Since I donm't know a
whole lot about electronics I asked here for information that would
help me diagnose the bad part or device. Probably I should have posted
the question in the basic electronics group too. In the end though I
though Jamie was being a little flippant. I felt my reply was a little
flip too. Now it has gotten out of hand. A more appropriate reply from
me would to have asked Jamie if he was being flippant. If he wasn't
then his answer would have been what he thought I was capable of, not
an unwarranted conclusion.
Cheers,
Eric
P.S.
This weekend I will attempt to find the bad cap, unsolder it and
replace it with a new one. If that doesn't work then it's time for
Jamie's solution.

[Michael A. Terrell]

stra...@yahoo.com wrote:
>
> You can buy a 500 W power factor corrected supply from Newegg for $40 and THEN get a $15 rebate. Buying good caps to redo your old supply will run $5-$10 and we haven't added the value of your time. Add another $5-$10 for a new cooling fan and you see how they are disposable.
>
> You must be young enough that the 'satisfaction' of repairing it has value but you'll get over it. Personally I replace power supplies but replace caps on motherboards to get going again. Repair the things that are hard to replace.
>
> Also there are nasty Voltages in the power supply but none on the mobo.

I always seem to need odd form factor power supplies, and they aren't
$25.

--
Anyone wanting to run for any political office in the US should have to
have a DD214, and a honorable discharge.

[Ralph Wade Phillips]

One more possibility ...

Most switch mode power supplies (well, most back when I was doing active
repairs!) use a "kick start" resistor to bleed some wall current AC into
the switcher, so that it'll start the cycle.

This used to be the most common failure point IME for cheaper switch
mode power supplies.

I'd check that also, if you don't find any bad caps.

RwP

--
I was sitting there, under my blanket, with fever and flu-like symptoms.
I was fuzzy in the head and having a hard time concentrating.
I had a horrible thought - "Is this what NORMAL feels like for average
IQ people??"