sci.electronics.repair - 25 new messages in 7 topics - digest

sci.electronics.repair
http://groups.google.com/group/sci.electronics.repair?hl=en

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Today's topics:

* Basic questions about telecommunications - 4 messages, 4 authors
http://groups.google.com/group/sci.electronics.repair/t/86ac7da2cbac660c?hl=en
* dell optiplex power supply - 1 messages, 1 author
http://groups.google.com/group/sci.electronics.repair/t/e0b329d22c943693?hl=en
* BETS HOT PHOTOS & VIDEOS - 1 messages, 1 author
http://groups.google.com/group/sci.electronics.repair/t/6aa0cb95341cad2c?hl=en
* UPS battery life - 11 messages, 8 authors
http://groups.google.com/group/sci.electronics.repair/t/b73fd839ce17fb50?hl=en
* Heathkit ETI-7040 Manual Wanted Universal Counter 175 MHz - 1 messages, 1
author
http://groups.google.com/group/sci.electronics.repair/t/68f783e836097763?hl=en
* Ricoh IS420 scanner question - 1 messages, 1 author
http://groups.google.com/group/sci.electronics.repair/t/103b3e1f145350f6?hl=en
* Canon A420 camera - 6 messages, 4 authors
http://groups.google.com/group/sci.electronics.repair/t/11a9e31849085804?hl=en

==============================================================================
TOPIC: Basic questions about telecommunications
http://groups.google.com/group/sci.electronics.repair/t/86ac7da2cbac660c?hl=en
==============================================================================

== 1 of 4 ==
Date: Sun, Jan 2 2011 12:29 am
From: Jeff Liebermann

On Sun, 02 Jan 2011 00:03:46 -0800, Jeff Liebermann <jeffl@cruzio.com>
wrote:

>I'll see if I can find
>another server that gives repeated data suitable for graphing.

This looks like a likely candidate:
<http://speedtestpro.net>
No clue if it works with W2K.

--
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

== 2 of 4 ==
Date: Sun, Jan 2 2011 1:47 am
From: David Nebenzahl

On 1/2/2011 12:03 AM Jeff Liebermann spake thus:

> Try this speed test:
> <http://www.ispgeeks.com/wild/modules.php?name=CapacityTest>
> It's not a nice neat graph as you were expecting, but it does give
> repeatable tests from a well connected server. I'll see if I can find
> another server that gives repeated data suitable for graphing.

I did try it. Interesting.

The test ran fine, but I was surprised to see the Java speed indicator
zoom up to ~700 kbps. I figured there was something perhaps bogus about
the speed test, but then I noticed that my Sygate monitor window also
showed speeds I'd never gotten before; the incoming (download) speed
went up to something like 120 K. Remember, my speeds usually bounce
between ~4 and ~6 K here.

So now I'm really confused. Are these transfer rates real? Remember, I'm
on a 56K modem.

Here's what they reported:

Your download capacity of 627 kbps is very low compared to most
broadband connections.*

Your upload capacity of 493 kbps is acceptable.

Your Quality of Service was measured at 30%, which shows that your
connection is unable to produce a constant stream of data.

* Except, of course, that I don't *have* a broadband connection!

Regarding your generous offer to perhaps set up a host for me to use to
check speeds, thanks, but remember this is just idle curiosity on my part.

If I ever have a real problem, maybe I'll take up your offer, and then
I'll really owe you one.

--
Comment on quaint Usenet customs, from Usenet:

To me, the *plonk...* reminds me of the old man at the public hearing
who stands to make his point, then removes his hearing aid as a sign
that he is not going to hear any rebuttals.

== 3 of 4 ==
Date: Sun, Jan 2 2011 2:24 am
From: "Geoffrey S. Mendelson"

David Nebenzahl wrote:
> The test ran fine, but I was surprised to see the Java speed indicator
> zoom up to ~700 kbps. I figured there was something perhaps bogus about
> the speed test, but then I noticed that my Sygate monitor window also
> showed speeds I'd never gotten before; the incoming (download) speed
> went up to something like 120 K. Remember, my speeds usually bounce
> between ~4 and ~6 K here.

It's accurate. As someone else mentioned the modems break the data into packets
as it is sending the data down the line. The data in each packet is compressed
before being sent.

If the speed test were to send truely (or close to it) random packets of 1024
random 8 bit patterns, they would travel at less than rated speed down the line
because there is overhead in packetizing the data, adding checksums, etc.

If the speed test sends a simple pattern, constantly repeated, then the modems
will compress it to a very small string and send that string down the line,
recreating at the far end.

So by analyzing packet timestamps, you could see that a 1k packet of data
comes down the phone line to the modem at some enourmous rate of speed, say
100 times what the line actually handles, and by the time the next packet
arrives, there is a long delay.

So it would show up as a very fast line with lots of instability in performance,
which in this case it is.

In a case with a more random spread of data, it would perform more to your
expectations.

If you wish to have a real test of how well your line performs, find a site
that lets you download video files and time downloading one from start to
finish. As far as modem compression algorythms, video data is almost
100% random and that will remove that variable.

I also would check carefully what you are paying for the combination of
telephone usage ISP charges. I understand the US is a telecom company's
regulatory paradise, but in many places in the world, a cheap broadband
connection has been cheaper than a dial up for many years.

Geoff.

--
Geoffrey S. Mendelson N3OWJ/4X1GM
Those who cannot remember the past are condemned to misquote it.

== 4 of 4 ==
Date: Sun, Jan 2 2011 11:31 am
From: dplatt@radagast.org (Dave Platt)

In article <4d2049a8$0$2417$822641b3@news.adtechcomputers.com>,
David Nebenzahl <nobody@but.us.chickens> wrote:

>I did try it. Interesting.
>
>The test ran fine, but I was surprised to see the Java speed indicator
>zoom up to ~700 kbps. I figured there was something perhaps bogus about
>the speed test, but then I noticed that my Sygate monitor window also
>showed speeds I'd never gotten before; the incoming (download) speed
>went up to something like 120 K. Remember, my speeds usually bounce
>between ~4 and ~6 K here.
>
>So now I'm really confused. Are these transfer rates real? Remember, I'm
>on a 56K modem.

It may very well depend on what data they're sending in their test.

Most modem connections incorporate V.42bis data compression. The
sending modem compresses the data before transmitting it, and the
receiving modem decompresses after validating the CRCs in the data
frames.

The effectiveness of the data compression will depend on the data
being sent. HTML, other ASCII text, etc. will usually compress fairly
well (2:1 isn't uncommon), test data consisting of just a single byte
(e.g. zeros) repeated over and over will compress *extremely* well,
and pre-compressed binary data (e.g. .zip archives, .png and .jpeg and
.mpg files) usually won't compress at all.

If the upload and download speed test consists of TCP streams full of
zeros or some other constant data, you could be getting extremely high
compression ratios, and thus an artifically-high link throughput number.

--
Dave Platt <dplatt@radagast.org> AE6EO
Friends of Jade Warrior home page: http://www.radagast.org/jade-warrior
I do _not_ wish to receive unsolicited commercial email, and I will
boycott any company which has the gall to send me such ads!

==============================================================================
TOPIC: dell optiplex power supply
http://groups.google.com/group/sci.electronics.repair/t/e0b329d22c943693?hl=en
==============================================================================

== 1 of 1 ==
Date: Sun, Jan 2 2011 4:19 am
From: bok118@zonnet.nl (Gerard Bok)

On Sat, 1 Jan 2011 06:53:23 -0800 (PST), n8ball
<natere2ster@gmail.com> wrote:

>I have a problem with my Optiplex 745 power supply, model H275P-01.
>
>I printed out the ATX 24 pin pinout and whats odd is when I short the
>pins to turn the unit on, its turns on ok.

Please note: (I do not know if this also applies to this
particular model) There are DELL PSUs around that use standard
plugs but with a slightly different wiring !

--
Kind regards,
Gerard Bok

==============================================================================
TOPIC: BETS HOT PHOTOS & VIDEOS
http://groups.google.com/group/sci.electronics.repair/t/6aa0cb95341cad2c?hl=en
==============================================================================

== 1 of 1 ==
Date: Sun, Jan 2 2011 7:59 am
From: SRAVANTHI LOVE

==============================================================================
TOPIC: UPS battery life
http://groups.google.com/group/sci.electronics.repair/t/b73fd839ce17fb50?hl=en
==============================================================================

== 1 of 11 ==
Date: Sun, Jan 2 2011 8:01 am
From: Andrew Rossmann

I have a battery I bought for an APC UPS about 4 years ago. I bought 2,
and used one immediately. I kept the other on the side as I have several
UPS's that use basically the same battery. Of course, over time, it has
discharged itself. I measured about 4.3V instead of the normal 12-13V. I
put it in a spare UPS, which immedialy complains if I try to turn it on.
Luckily, the UPS charges even when it is off, but slowly. I measured
about 15mA initially, and after about 36 hours, about 7.5mA. It is
currently up to about 10.7V.

How much damage do you think was done to the battery? I know it will
lose some capacity.

--
If there is a no_junk in my address, please REMOVE it before replying!
All junk mail senders will be prosecuted to the fullest extent of the
law!!
http://home.comcast.net/~andyross

== 2 of 11 ==
Date: Sun, Jan 2 2011 8:22 am
From: nesesu

On Jan 2, 8:01 am, Andrew Rossmann
<andysnewsreply@no_junk.comcast.net> wrote:
> I have a battery I bought for an APC UPS about 4 years ago. I bought 2,
> and used one immediately. I kept the other on the side as I have several
> UPS's that use basically the same battery. Of course, over time, it has
> discharged itself. I measured about 4.3V instead of the normal 12-13V. I
> put it in a spare UPS, which immedialy complains if I try to turn it on.
> Luckily, the UPS charges even when it is off, but slowly. I measured
> about 15mA initially, and after about 36 hours, about 7.5mA. It is
> currently up to about 10.7V.
>
> How much damage do you think was done to the battery? I know it will
> lose some capacity.
>
> --
> If there is a no_junk in my address, please REMOVE it before replying!
> All junk mail senders will be prosecuted to the fullest extent of the
> law!!http://home.comcast.net/~andyross

Andy, It sounds like it may be at least partially sulphated now. I
would turn on the UPS and put a heavier charge rate into it, or, if
that is not possible, then charge it with an external 12V charger. If
it does take a charge, then cycle it a couple of times [discharge/
charge] and then measure how it performs in the UPS under moderate
load. You may have caught it in time, or it may be too far gone. One
really good indicator is if the batttery case has bulged so that there
is a distinct bulge in the sides and ends between the cell separators,
then the battery is definitely 'toast'.

Neil S.

== 3 of 11 ==
Date: Sun, Jan 2 2011 8:41 am
From: Jeffrey Angus

On 1/2/2011 10:01 AM, Andrew Rossmann wrote:
> I have a battery I bought for an APC UPS about 4 years ago.
> I bought 2, and used one immediately.

There's a reason alarm companies change the sealed lead
acid batteries annually. Typical life on them is about
2 years. 4 years on the shelf is well, not good.

Keeping them charged up at all times is the only way to
keep them (or any lead cell) happy and useful.

Jeff

== 4 of 11 ==
Date: Sun, Jan 2 2011 8:49 am
From: "Ian Field"

"Andrew Rossmann" <andysnewsreply@no_junk.comcast.net> wrote in message
news:MPG.278a5d698320a03498976c@news.eternal-september.org...
>I have a battery I bought for an APC UPS about 4 years ago. I bought 2,
> and used one immediately. I kept the other on the side as I have several
> UPS's that use basically the same battery. Of course, over time, it has
> discharged itself. I measured about 4.3V instead of the normal 12-13V. I
> put it in a spare UPS, which immedialy complains if I try to turn it on.
> Luckily, the UPS charges even when it is off, but slowly. I measured
> about 15mA initially, and after about 36 hours, about 7.5mA. It is
> currently up to about 10.7V.
>
> How much damage do you think was done to the battery? I know it will
> lose some capacity.
>
> --
> If there is a no_junk in my address, please REMOVE it before replying!
> All junk mail senders will be prosecuted to the fullest extent of the
> law!!
> http://home.comcast.net/~andyross
>

Next time you buy a spare battery to save for later, buy a dry-charged
battery with the acid in a separate bottle/applicator.

The Varta motorcycle battery I bought before the UK VAT increase came with a
DIY filling kit so I could store it till I need it, with a bit of shopping
around you should be able to find a DIY filling kit SLA.

== 5 of 11 ==
Date: Sun, Jan 2 2011 9:10 am
From: PeterD

On Sun, 2 Jan 2011 10:01:46 -0600, Andrew Rossmann
<andysnewsreply@no_junk.comcast.net> wrote:

>How much damage do you think was done to the battery? I know it will
>lose some capacity.

The battery is likely 'toast' now, I'd suggest replacing it. If you
have a compatible desulfating charger you could try desulfating it,
but I suspect there is little or no hope.

== 6 of 11 ==
Date: Sun, Jan 2 2011 9:35 am
From: Andrew Rossmann

In article <771c632e-4b2a-4fb9-998f-
7845b7905d2a@r16g2000prh.googlegroups.com>, neil_sutcliffe@telus.net
says...
> Andy, It sounds like it may be at least partially sulphated now. I
> would turn on the UPS and put a heavier charge rate into it, or, if
> that is not possible, then charge it with an external 12V charger. If
> it does take a charge, then cycle it a couple of times [discharge/
> charge] and then measure how it performs in the UPS under moderate
> load. You may have caught it in time, or it may be too far gone. One
> really good indicator is if the batttery case has bulged so that there
> is a distinct bulge in the sides and ends between the cell separators,
> then the battery is definitely 'toast'.

The battery is physically in good condition. No bulging or anything like
that. Given how low the charge rate is, it'll probably take another day
or two to fully charge. I've seen this battery for about $14 at Amazon,
so it's not that expensive (the shipping is almost as much!) If I can
get it to the point where the UPS doesn't scream 'replace battery', I
can then test it to see how well it works.

I don't have any other real charging source, or at least something I'd
consider safe. The only 12V source I have is an old Radio Shack
regulated 12V@2.5A supply, or some wall warts. The charging rate is low,
but I assume it's probably safer and better for the battery than trying
to charge it quickly?

This all came to a head due to a power outage on Friday. The battery in
one UPS (APC Back UPS 725 ES, 7 AH battery, probably 6+ years old) only
lasted about 5 minutes powering a cable DVR, VCR, and an RF modulator. I
wanted to replace it, but this battery was too weak. Another UPS (same
as the other) running my modem and router ran for an hour before I
decided to turn it off.

--
If there is a no_junk in my address, please REMOVE it before replying!
All junk mail senders will be prosecuted to the fullest extent of the
law!!
http://home.comcast.net/~andyross

== 7 of 11 ==
Date: Sun, Jan 2 2011 9:47 am
From: Jeff Liebermann

On Sun, 2 Jan 2011 10:01:46 -0600, Andrew Rossmann
<andysnewsreply@no_junk.comcast.net> wrote:

>I have a battery I bought for an APC UPS about 4 years ago. I bought 2,
>and used one immediately.

Model number please? I'm curious.

>I kept the other on the side as I have several
>UPS's that use basically the same battery. Of course, over time, it has
>discharged itself.

If you let a gel cell battery run down for an extended period, it will
sulfate itself rather nicely. Once the terminal voltage drops below
about 11VDC, it's on it's way to the recyclers. I have to charge my
stock of SLA batteries every 6 months or I end up with dead batteries.
Sometimes, even with a 6 month recharge, my older used batteries die.
After 4 years, you have the added enjoyment of plate corrosion, which
is not reversable. For my amusement, I once tore apart a dead SLA
battery to see what's inside. To my surprise, both the lead
(positive) and lead dioxide (negative) plates looked like rather
corroded.

>I measured about 4.3V instead of the normal 12-13V.

Yep, it's almost dead, but not quite. It might be possible to recover
by overcharging. See:
<http://batteryuniversity.com/learn/article/how_to_restore_and_prolong_lead_acid_batteries>

>I
>put it in a spare UPS, which immedialy complains if I try to turn it on.
>Luckily, the UPS charges even when it is off, but slowly. I measured
>about 15mA initially, and after about 36 hours, about 7.5mA. It is
>currently up to about 10.7V.

I've often suspected that UPS charging circuits were a bit too
aggressive and have a detrimental effect on battery life. My
conspiracy theory is that most people don't bother to replace dead
batteries and will replace the entire UPS instead. So, premature
battery death will result in more UPS sales. However, the problem is
that UPS's are sold based on their run time and somewhat on how fast
they recharge after a power failure. So, the charging circuits are
designed to squeeze as much charge into the battery as possible, in as
short a time period, rather than for long life.
<http://robots.freehostia.com/Batteries/Batteries.html>

>How much damage do you think was done to the battery? I know it will
>lose some capacity.

Dunno. I've had zero luck with recovering an SLA battery that's been
run down that far.

--
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

== 8 of 11 ==
Date: Sun, Jan 2 2011 11:40 am
From: dplatt@radagast.org (Dave Platt)

In article <MPG.278a5d698320a03498976c@news.eternal-september.org>,
Andrew Rossmann <andysnewsreply@no_junk.comcast.net> wrote:

>I have a battery I bought for an APC UPS about 4 years ago. I bought 2,
>and used one immediately. I kept the other on the side as I have several
>UPS's that use basically the same battery. Of course, over time, it has
>discharged itself. I measured about 4.3V instead of the normal 12-13V. I
>put it in a spare UPS, which immedialy complains if I try to turn it on.
>Luckily, the UPS charges even when it is off, but slowly. I measured
>about 15mA initially, and after about 36 hours, about 7.5mA. It is
>currently up to about 10.7V.
>
>How much damage do you think was done to the battery? I know it will
>lose some capacity.

It sounds as if the battery has become badly sulphated. This is not
uncommon if you let a lead-acid battery sit around un-used... the
lead plates have become coated with a layer of lead sulphate, in a
crystalline form which is both insulating, and difficult to convert
back to a soluble form. The battery now looks pretty much like an
open circuit to the UPS, as it has a very high resistance, and it will
not accept a charge efficiently from the recharging circuit.

To keep this from happening (in the future) it's best to keep the
battery fully charged, via a "float-charge" mechanism at just the
right voltage (which depends somewhat on the temperature).

There are techniques which can be used to de-sulphate a battery and
restore it to at least some degree of usefulness. The techniques
vary in detail, but usually involve applying a higher voltage to the
battery (with a careful limit on the amount of current available!) to
break down the sulphate crystals and allow them to re-dissolve. This
is sometimes done via a "pulser" (which generates short high-voltage
pulses) and sometimes through a dedicated high-voltage supply.

Whether a badly sulphated battery can ever be returned to a
substantial fraction of its original capacity seems to be a somewhat
controversial question... some say yes, some say no. It may depend a
lot on the specifics of the battery type and the degree of sulphation.

Your best bet is probably to just buy a fresh battery, when you know
you need it for one of your USP systems... and check the date code on
the new battery before you buy it to make sure it's really fresh and
hasn't been sitting on a shelf for several years!

== 9 of 11 ==
Date: Sun, Jan 2 2011 12:59 pm
From: nesesu

On Jan 2, 11:40 am, dpl...@radagast.org (Dave Platt) wrote:
> In article <MPG.278a5d698320a034989...@news.eternal-september.org>,
> Andrew Rossmann <andysnewsreply@no_junk.comcast.net> wrote:
>
> >I have a battery I bought for an APC UPS about 4 years ago. I bought 2,
> >and used one immediately. I kept the other on the side as I have several
> >UPS's that use basically the same battery. Of course, over time, it has
> >discharged itself. I measured about 4.3V instead of the normal 12-13V. I
> >put it in a spare UPS, which immedialy complains if I try to turn it on.
> >Luckily, the UPS charges even when it is off, but slowly. I measured
> >about 15mA initially, and after about 36 hours, about 7.5mA. It is
> >currently up to about 10.7V.
>
> >How much damage do you think was done to the battery? I know it will
> >lose some capacity.
>
> It sounds as if the battery has become badly sulphated. This is not
> uncommon if you let a lead-acid battery sit around un-used... the
> lead plates have become coated with a layer of lead sulphate, in a
> crystalline form which is both insulating, and difficult to convert
> back to a soluble form. The battery now looks pretty much like an
> open circuit to the UPS, as it has a very high resistance, and it will
> not accept a charge efficiently from the recharging circuit.
>
> To keep this from happening (in the future) it's best to keep the
> battery fully charged, via a "float-charge" mechanism at just the
> right voltage (which depends somewhat on the temperature).
>
> There are techniques which can be used to de-sulphate a battery and
> restore it to at least some degree of usefulness. The techniques
> vary in detail, but usually involve applying a higher voltage to the
> battery (with a careful limit on the amount of current available!) to
> break down the sulphate crystals and allow them to re-dissolve. This
> is sometimes done via a "pulser" (which generates short high-voltage
> pulses) and sometimes through a dedicated high-voltage supply.
>
> Whether a badly sulphated battery can ever be returned to a
> substantial fraction of its original capacity seems to be a somewhat
> controversial question... some say yes, some say no. It may depend a
> lot on the specifics of the battery type and the degree of sulphation.
>
> Your best bet is probably to just buy a fresh battery, when you know
> you need it for one of your USP systems... and check the date code on
> the new battery before you buy it to make sure it's really fresh and
> hasn't been sitting on a shelf for several years!
>
> --
> Dave Platt <dpl...@radagast.org> AE6EO
> Friends of Jade Warrior home page: http://www.radagast.org/jade-warrior
> I do _not_ wish to receive unsolicited commercial email, and I will
> boycott any company which has the gall to send me such ads!

Usually you need to buy the battery a couple of days BEFORE you
discover you need it :-)

At work we had a very large UPS that used 600V of gel-cell 12V
batteries each about the size of a largish car battery. In the 15
years or so that it was in use, there were, perhaps, 5 power failures
and the UPS failed every time even though all the routine maintenance
and testing was observed. Other than the first time when it was only a
month or so old and the inverter blew up [linerally] all the rest of
the failures were due to battery failure.

Neil S.

== 10 of 11 ==
Date: Sun, Jan 2 2011 1:32 pm
From: D Yuniskis

On 1/2/2011 9:41 AM, Jeffrey Angus wrote:
> On 1/2/2011 10:01 AM, Andrew Rossmann wrote:
>> I have a battery I bought for an APC UPS about 4 years ago.
>> I bought 2, and used one immediately.
>
> There's a reason alarm companies change the sealed lead
> acid batteries annually. Typical life on them is about
> 2 years. 4 years on the shelf is well, not good.
>
> Keeping them charged up at all times is the only way to
> keep them (or any lead cell) happy and useful.

You can also lower the specific gravity of the cells
to prolong life. Of course, only applies to *wet* cells.

== 11 of 11 ==
Date: Sun, Jan 2 2011 1:50 pm
From: Jeff Liebermann

On Sun, 2 Jan 2011 11:40:33 -0800, dplatt@radagast.org (Dave Platt)
wrote:

>Whether a badly sulphated battery can ever be returned to a
>substantial fraction of its original capacity seems to be a somewhat
>controversial question... some say yes, some say no. It may depend a
>lot on the specifics of the battery type and the degree of sulphation.

I say maybe. One trick that I've tried, that has worked with lightly
to moderately sulfated batteries, is to clamp it in a paint shaker and
shake along the axis of the plates. If you can't find a paint shaker,
I've used a Sawzall with a custom shaker attachment.
<http://www.youtube.com/watch?v=4ZlJ05SJwpU>
Anything that reciprocates will work. The idea is to get the gel or
liquid electrolyte to slosh around, hopefully causing the lead
sulphate coating to break off and fall to the bottom. Unfortunately,
if the plates are badly corroded, instead of the lead sulfate falling
off, the plates will crumble. As a side benefit, you'll get quite an
arm massage with a heavy battery. My batting average is about 50% so
this is not a reliable method. Still, it has produced a few
miraculous battery recoveries.

--
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: Heathkit ETI-7040 Manual Wanted Universal Counter 175 MHz
http://groups.google.com/group/sci.electronics.repair/t/68f783e836097763?hl=en
==============================================================================

== 1 of 1 ==
Date: Sun, Jan 2 2011 8:42 am
From: nesesu

On Jan 1, 4:38 pm, "Wild_Bill" <wb_wildb...@XSPAMyahoo.com> wrote:
> Thanks Neil.. my suspicion is as you suggested, as I've seen waveforms
> present at the 2 inputs of the counter IC with signal generator inputs at
> Input A & B, and that perhaps one of a couple of other ICs may be the
> culprit.
>
> In numerical order, just before the ICM7226 counter IC there are:
> U18 quad 2-input Exclusive-OR
> U19 HD74LS74AP dual D-type positive edge triggered F-flops with reset and
> clear
>
> Of course, there are numerous other signals to the counter IC that are
> essential for proper operation, where I believe a schematic would be most
> helpful.
> There is a Test Point pin TP1 beside U18, for example.
>
> The only obvious non-factory soldering is around the input area of the Input
> A circuit components, where it appears that some resistor leads were lifted
> to check their values.
> The soldering under the sockets for the 2 newer ICs (U18 and counter IC U20)
> looks identical to the rest of the wave-soldered factory assembly
> connections, although oddly enough those 2 ICs are the only ones with
> sockets.
>
> FWIW, I wouldn't claim that it's not possible for me to be fooled, but I've
> seen a lot of soldering and hand soldering generally always has certain
> characteristics that differ from factory connections, such as inconsistent
> amounts of solder applied to some pads and several other traits.
>
> --
> Cheers,
> WB
> .............
>
> "nesesu" <neil_sutcli...@telus.net> wrote in message
>
> news:854be12d-a25e-4bb3-8e1d-c2a1d6dbfcb1@35g2000prb.googlegroups.com...
>
> My incination would be to closely examine the soldering, both rework
> and original. If that looks good, then apply the same signal of about
> 1 kHz sine to both inputs and compare the signal at the A and B input
> pins on the counter chip with a good 'scope. Vary the input level and
> see that the processed signals remain identical. If the signals are
> identical, then the two input channels are probably okay and the
> problem lies in the the control circuitry or the counter chip. Since
> you see operation when probing, that suggested the counter chip is
> good, but thre is a fault in it's control due to some sort of poor
> connection such as solder, a dirty switch as N. Cook suggests, or even
> 'lead rot' on one or more DIP packages.
>
> Neil S.

This data sheet looks like it gives enough information to trace
through the operating parameters of the chip in your application.
Heath was known to utilize the 'typical application' circuits of the
manufacturers, so I would not be surprised to find the data sheet
fairly close to the circuit you have. This also explains the various
functions of the controls.
http://www.electroniccircuits.gr/files/ICM7226.pdf

Neil S.

==============================================================================
TOPIC: Ricoh IS420 scanner question
http://groups.google.com/group/sci.electronics.repair/t/103b3e1f145350f6?hl=en
==============================================================================

== 1 of 1 ==
Date: Sun, Jan 2 2011 9:21 am
From: "Desert Tripper"

Bought a Ricoh IS420 at a local thrift shop. The scanner overall is in excellent condition and looks lightly used - all tires are in great shape.

However: when using the ADF, the first page scans just fine. But the second page is never picked up - scanner errors out and according to the user manual, the error light pattern is "Paper Misfeed." The ADF does not even attempt to pick up the second page.

The problem is consistent. I have verified with a voltmeter that the photodetectors are functioning properly and that there are no foreign objects in the paper path.

I would appreciate any nudges in the right direction, or at least a link to the IS420 (or similar model) service manual.

Doug

--------------= Posted using GrabIt =----------------
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==============================================================================
TOPIC: Canon A420 camera
http://groups.google.com/group/sci.electronics.repair/t/11a9e31849085804?hl=en
==============================================================================

== 1 of 6 ==
Date: Sun, Jan 2 2011 10:34 am
From: adrian@poppyrecords.invalid.invalid (Adrian Tuddenham)

I have a three year old Canon A420 which has been working perfectly
until last week. Now pictures are coming out grossly over-exposed,
although they look satisfactory on the LCD screen right up to the point
where the release button is pressed.

Moving from light to dark subjects, the system adjusts the image on the
screen to the changes in light level in a normal manner. Holding the
release button half way down 'freezes' a satisfactory picture, but then,
after pressing it the rest of the way, the stored result is whited-out.

The storage card appears to work normally and an external card reader
allows me to store and retrieve other images undamaged.

By deliberately choosing dark subject matter or something which needs
flash, I can force the correct exposure. The picture then appears to
have a fine horizontal line structure imposed on it.

I have re-set the camera by removing both power and memory batteriea,
and fitted new batteries, but it makes no difference.

The camera has not been dropped or exposed to damp, although it was
recently subjected to unusually cold conditions whilst taking snow
photographs. The rotary function selector switch became very stiff and
then eased-up suddenly just when the fault appeared - but I do not see
any obvious connection between the two events.

Does the switch have multiple contacts? Any other suggestions?

--
~ Adrian Tuddenham ~
(Remove the ".invalid"s and add ".co.uk" to reply)
www.poppyrecords.co.uk

== 2 of 6 ==
Date: Sun, Jan 2 2011 10:46 am
From: Meat Plow

On Sun, 02 Jan 2011 18:34:00 +0000, Adrian Tuddenham wrote:

> I have a three year old Canon A420 which has been working perfectly
> until last week. Now pictures are coming out grossly over-exposed,
> although they look satisfactory on the LCD screen right up to the point
> where the release button is pressed.
>
> Moving from light to dark subjects, the system adjusts the image on the
> screen to the changes in light level in a normal manner. Holding the
> release button half way down 'freezes' a satisfactory picture, but then,
> after pressing it the rest of the way, the stored result is whited-out.
>
> The storage card appears to work normally and an external card reader
> allows me to store and retrieve other images undamaged.
>
> By deliberately choosing dark subject matter or something which needs
> flash, I can force the correct exposure. The picture then appears to
> have a fine horizontal line structure imposed on it.
>
>
> I have re-set the camera by removing both power and memory batteriea,
> and fitted new batteries, but it makes no difference.
>
> The camera has not been dropped or exposed to damp, although it was
> recently subjected to unusually cold conditions whilst taking snow
> photographs. The rotary function selector switch became very stiff and
> then eased-up suddenly just when the fault appeared - but I do not see
> any obvious connection between the two events.
>
> Does the switch have multiple contacts? Any other suggestions?

Find someone who can repair it for less than a new camera would cost.

--
Live Fast, Die Young and Leave a Pretty Corpse

== 3 of 6 ==
Date: Sun, Jan 2 2011 1:56 pm
From: "John Keiser"

Is this in all modes - Auto, Program, etc?

"Adrian Tuddenham" <adrian@poppyrecords.invalid.invalid> wrote in message
news:1juhc12.qrk4l01d9deikN%adrian@poppyrecords.invalid.invalid...
>I have a three year old Canon A420 which has been working perfectly
> until last week. Now pictures are coming out grossly over-exposed,
> although they look satisfactory on the LCD screen right up to the point
> where the release button is pressed.
>
> Moving from light to dark subjects, the system adjusts the image on the
> screen to the changes in light level in a normal manner. Holding the
> release button half way down 'freezes' a satisfactory picture, but then,
> after pressing it the rest of the way, the stored result is whited-out.
>
> The storage card appears to work normally and an external card reader
> allows me to store and retrieve other images undamaged.
>
> By deliberately choosing dark subject matter or something which needs
> flash, I can force the correct exposure. The picture then appears to
> have a fine horizontal line structure imposed on it.
>
>
> I have re-set the camera by removing both power and memory batteriea,
> and fitted new batteries, but it makes no difference.
>
> The camera has not been dropped or exposed to damp, although it was
> recently subjected to unusually cold conditions whilst taking snow
> photographs. The rotary function selector switch became very stiff and
> then eased-up suddenly just when the fault appeared - but I do not see
> any obvious connection between the two events.
>
> Does the switch have multiple contacts? Any other suggestions?
>
> --
> ~ Adrian Tuddenham ~
> (Remove the ".invalid"s and add ".co.uk" to reply)
> www.poppyrecords.co.uk

== 4 of 6 ==
Date: Sun, Jan 2 2011 2:01 pm
From: Jeff Liebermann

On Sun, 2 Jan 2011 18:34:00 +0000, adrian@poppyrecords.invalid.invalid
(Adrian Tuddenham) wrote:

>I have a three year old Canon A420 which has been working perfectly
>until last week.

The warranty on the Canon A420 is 3 years. You might check with Canon
if it's still under warranty and can be fixed for free.
<http://www.usa.canon.com/cusa/support/consumer/digital_cameras/powershot_a_series/powershot_a420>
<http://www.usa.canon.com/cusa/consumer?pageKeyCode=repairLanding>

--
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

== 5 of 6 ==
Date: Sun, Jan 2 2011 2:10 pm
From: Jeff Liebermann

On Sun, 02 Jan 2011 14:01:23 -0800, Jeff Liebermann <jeffl@cruzio.com>
wrote:

>On Sun, 2 Jan 2011 18:34:00 +0000, adrian@poppyrecords.invalid.invalid
>(Adrian Tuddenham) wrote:
>
>>I have a three year old Canon A420 which has been working perfectly
>>until last week.

>The warranty on the Canon A420 is 3 years. You might check with Canon
>if it's still under warranty and can be fixed for free.
><http://www.usa.canon.com/cusa/support/consumer/digital_cameras/powershot_a_series/powershot_a420>
><http://www.usa.canon.com/cusa/consumer?pageKeyCode=repairLanding>

Never mind. The original Canon warranty is only 1 year. Some dealers
offered 3 year warranties if you buy from them. Sorry for the
misinformation.

--
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

== 6 of 6 ==
Date: Sun, Jan 2 2011 2:33 pm
From: adrian@poppyrecords.invalid.invalid (Adrian Tuddenham)

John Keiser <john.keiser2@hawaiiantel.net> wrote:

> Is this in all modes - Auto, Program, etc?

It seems to be.

Even using it with the manual exposure at its darkest setting gives
over-exposure and a coarse 'raster' effect.

I have now noticed that the display has a slight flicker which I don't
remember seeing before.

--
~ Adrian Tuddenham ~
(Remove the ".invalid"s and add ".co.uk" to reply)
www.poppyrecords.co.uk

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