sci.electronics.repair@googlegroups.com

Today's topics:

* OT: archiving on CD/DVD - 5 messages, 5 authors
http://groups.google.com/group/sci.electronics.repair/t/7865cc1a1f8d8699?hl=en
* Update - Sony model KDS 60-A2000 dreaded blinking led - 1 messages, 1 author
http://groups.google.com/group/sci.electronics.repair/t/60cdd0d98767a91a?hl=en
* IC-28A transmit section carnage - 3 messages, 3 authors
http://groups.google.com/group/sci.electronics.repair/t/2d64dac1e201e106?hl=en
* DTV decoder repair, capacitor gets too hot - 1 messages, 1 author
http://groups.google.com/group/sci.electronics.repair/t/2a64f4c6ccba41cd?hl=en

==============================================================================
TOPIC: OT: archiving on CD/DVD
http://groups.google.com/group/sci.electronics.repair/t/7865cc1a1f8d8699?hl=en
==============================================================================

== 1 of 5 ==
Date: Mon, May 31 2010 3:04 pm
From: "Michael A. Terrell"

Jeffrey D Angus wrote:
>
> D Yuniskis wrote:
> > Best advice: decide what things you are willing to "lose";
> > then ask yourself, "If I am willing to lose it, is there
> > any reason why I shouldn't (deliberately!) lose it *now*??"
>
> Oh yeah, definitely. Periodically I get the "urge" and act
> like your typical B-movie crazed ax murderer and clean house.

Or just move half way across the country. ;-)

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

== 2 of 5 ==
Date: Mon, May 31 2010 4:20 pm
From: Franc Zabkar

On Sun, 30 May 2010 18:51:44 +0100, "N_Cook" <diverse@tcp.co.uk> put
finger to keyboard and composed:

>Anyone else got any tips ?

I make it a policy to fill up the entire CD, if only with redundant
copies.

For example, let's say you have 100MB of photo files. I'd copy these
same files to 7 directories, ie COPY_1, COPY_2, ... COPY_7. That way
you have 7 chances to recover your precious snaps in the event of
physical damage, CD rot, unreliable burner, unreliable media, etc.

- Franc Zabkar
--
Please remove one 'i' from my address when replying by email.

== 3 of 5 ==
Date: Mon, May 31 2010 5:03 pm
From: Grant

On Tue, 01 Jun 2010 09:20:42 +1000, Franc Zabkar <fzabkar@iinternode.on.net> wrote:

>On Sun, 30 May 2010 18:51:44 +0100, "N_Cook" <diverse@tcp.co.uk> put
>finger to keyboard and composed:
>
>>Anyone else got any tips ?
>
>I make it a policy to fill up the entire CD, if only with redundant
>copies.
>
>For example, let's say you have 100MB of photo files. I'd copy these
>same files to 7 directories, ie COPY_1, COPY_2, ... COPY_7. That way
>you have 7 chances to recover your precious snaps in the event of
>physical damage, CD rot, unreliable burner, unreliable media, etc.

Burn slow and verify too, works for me :)

Grant.
--
http://bugs.id.au/

== 4 of 5 ==
Date: Mon, May 31 2010 5:19 pm
From: "Charlie"

"N_Cook" <diverse@tcp.co.uk> wrote in message
news:htu8gf$d49$1@news.eternal-september.org...
> BBC click this week did a feature
> http://news.bbc.co.uk/1/hi/programmes/click_online/8711747.stm
> Using apparently high spec discs is no guarantee of longevity.
> Mention of what I happen to do, copy 3 yearold backups to new on a rolling
> basis and keeping in 2 different sites for storage. I also check originals
> at the same time for any degradation. No mention of writing at reduced
> speed
> for archiving purposes. I happpen to always knock down from x52 to 40 for
> normal burning (slightly larger pits) and then x32 for 3 yearlt archives.
> French researcher shown cleaning dics radially , not circumferentially.
> Shame BBC reporter did not mention this factor.
> Anyone else got any tips ?
>
>
> --
> Diverse Devices, Southampton, England
> electronic hints and repair briefs , schematics/manuals list on
> http://diverse.4mg.com/index.htm
>

What everybody seems to key onto is the useful life of the media,

What might be more of a problem is the useful life of devices to read that
media.

Case in point. A friend who runs a small shop called and wanted to transfer
her business file to a new computer.
The stumbling point was that the media was 5.25 inch floppies.
Don't bother criticizing her for being stuck with an obsolete system.

Consider tape backups or even 2.5 inch floppies.

Ten years will those carefully preserved CDs been totally replaced by (fill
in the blank with your guess and bet your data on it).

Charlie

== 5 of 5 ==
Date: Mon, May 31 2010 6:20 pm
From: D Yuniskis

Hi Charlie,

Charlie wrote:

> What everybody seems to key onto is the useful life of the media,

Because once the media is toast, there's nothing more you can do.

> What might be more of a problem is the useful life of devices to read that
> media.
>
> Case in point. A friend who runs a small shop called and wanted to transfer
> her business file to a new computer.
> The stumbling point was that the media was 5.25 inch floppies.
> Don't bother criticizing her for being stuck with an obsolete system.
>
> Consider tape backups or even 2.5 inch floppies.
>
> Ten years will those carefully preserved CDs been totally replaced by (fill
> in the blank with your guess and bet your data on it).

<grin> Keep lots of spares! (I have 5 or 6 DLT transports, and no
fewer than 2 or 3 of every other "drive" -- even 8" floppies! :> )

Making backups (that you actually expect to be able to use!)
is a costly undertaking.

==============================================================================
TOPIC: Update - Sony model KDS 60-A2000 dreaded blinking led
http://groups.google.com/group/sci.electronics.repair/t/60cdd0d98767a91a?hl=en
==============================================================================

== 1 of 1 ==
Date: Mon, May 31 2010 5:15 pm
From: stokesbr@cox.net

Original problem - Won't power up. Power led blinking 4 times. Called
Sony for blink code troubleshooting, rep said it meant power supply
problem to lamp or backlight (I did give her the correct model #), and
she proceeded to direct me to the nearest authorized Sony tech. After
work, I opened set and checked voltage at lamp power board - OK.
Unplugged set and plugged back in. This time before shutdown, I saw an
arc between R-6500 and lamp power cord plug on main PB. I bent the
resistor away from the plug. Plugged set back in, now getting the 5
led blink code. Time to turn in. Next day got my hands on a service
manual. It says the 4 blink code is a fan problem, NOT LAMP, and the 5
blink is lamp driver. Next day checked power again to lamp board,
nothing. Nothing coming from main board either. Checked R-6500 and it
was open. Replaced with .47ohm 1/2 fusible resistor and set back to
normal finally. Iv'e never seen a resistor behave like that, but I
don't do this for a living either. Couldn't believe I was misdirected
by Sony rep on the blink code. Hope this repair tip helps someone else
visiting this group. Thanks for the previous replies all. Until
later........

==============================================================================
TOPIC: IC-28A transmit section carnage
http://groups.google.com/group/sci.electronics.repair/t/2d64dac1e201e106?hl=en
==============================================================================

== 1 of 3 ==
Date: Mon, May 31 2010 6:15 pm
From: David Brodbeck

For those curious how this went:

I replaced Q17 and C54.

I now have correct voltages on all four pins of the PA module in
transmit mode, but still almost no power output -- I suspect a bad PA
module, at this point. Reinforcing this is the fact that I appear to
have more signal on the input of the PA module than I have on the
output.

I think I'm going to set this one aside and just use it as a receiver;
at this point it's not worth spending much more time on, unless I run
across another IC-28A with a different problem.

== 2 of 3 ==
Date: Mon, May 31 2010 6:41 pm
From: Jamie

David Brodbeck wrote:

> For those curious how this went:
>
> I replaced Q17 and C54.
>
> I now have correct voltages on all four pins of the PA module in
> transmit mode, but still almost no power output -- I suspect a bad PA
> module, at this point. Reinforcing this is the fact that I appear to
> have more signal on the input of the PA module than I have on the
> output.
>
> I think I'm going to set this one aside and just use it as a receiver;
> at this point it's not worth spending much more time on, unless I run
> across another IC-28A with a different problem.
Your assumption is most likely correct... I can give you an idea how
ever.. If you can remove the cover of the module, and inspect the board,
you may find a crack. You'll need a high temp soldering iron to put it
back together.. This is common with RF modules or various types.

I've done this 3 times already on different rigs and it worked. Most
of the time a crack develops, mostly from abuse. Other times, you have
a bad module..

== 3 of 3 ==
Date: Mon, May 31 2010 7:35 pm
From: Jeff Liebermann

On Mon, 31 May 2010 21:41:25 -0400, Jamie
<jamie_ka1lpa_not_valid_after_ka1lpa_@charter.net> wrote:

>Your assumption is most likely correct... I can give you an idea how
>ever.. If you can remove the cover of the module, and inspect the board,
>you may find a crack. You'll need a high temp soldering iron to put it
>back together.. This is common with RF modules or various types.
>
>I've done this 3 times already on different rigs and it worked. Most
>of the time a crack develops, mostly from abuse. Other times, you have
>a bad module..

It doesn't require abuse. See:
<http://www.11junk.com/jeffl/pics/drivel/slides/power-amp.html>
That's the guts of the VHF power module from my Kenwood TM-732A radio.
The circled areas are where I had to solder the trace back together.
The two failures were seperated by about 2 years and will probably
continue at the same interval. My guess(tm) is that it was caused by
either incomplete baking of the hybrid, or a bad solder paste mix when
the hybrid was silk screened.

The gaps were almost invisible and very difficult to see. They would
have been far more visible if I could have shined a light from the
back, but there's a big copper heat spreader in the way. Instead, I
found them with an ohmmeter. I started with the probes at the end of
the conductor trace, which showed no continuity. I slowly moved the
probes closer to each other and eventually closed in on the break.

Soldering was also rather difficult. The ceramic hybrid is a
wonderful heatsink and literally sucks all the heat out of the
soldering iron. I had to use a rather large 850C screwdriver solder
tip and still managed to do a lousy job of soldering.

Also note on the photograph the two big power xsistors. The goo
covering them is rather soft and flexible silicon rubber. Please
resist the temptation to push on it, or you'll break the wire bonds
underneath.

If desperate, you can get replacement PA modules from RF Parts.

--
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

==============================================================================
TOPIC: DTV decoder repair, capacitor gets too hot
http://groups.google.com/group/sci.electronics.repair/t/2a64f4c6ccba41cd?hl=en
==============================================================================

== 1 of 1 ==
Date: Mon, May 31 2010 6:35 pm
From: Franc Zabkar

On Mon, 31 May 2010 10:12:44 +1000, Grant <omg@grrr.id.au> put finger
to keyboard and composed:

>Quick check for 1000/25 and 1000/35 Panasonic caps
>show ESR goes from .033 down to .025 for higher volt rating.

I just tried a thought experiment, but it failed. :-(

Let's say we have four identical capacitors, each with capacitance C,
esr R, and voltage rating V.

If we connect them as follows, we would expect the equivalent
capacitor to have a capacitance C, esr R, and voltage rating 2V.

|| ||
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- Franc Zabkar
--
Please remove one 'i' from my address when replying by email.

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