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

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

sci.electronics.repair@googlegroups.com

Today's topics:

* LCD display on exercize bike troubleshooting. - 4 messages, 3 authors
http://groups.google.com/group/sci.electronics.repair/t/eb9e9b51f65d17e8?hl=en
* Tapco Juice J 2500 slave amp, 2007 - 3 messages, 1 author
http://groups.google.com/group/sci.electronics.repair/t/185ab3fdb182c05a?hl=en
* american beer inferier? - 2 messages, 2 authors
http://groups.google.com/group/sci.electronics.repair/t/79cf21563e25cfa2?hl=en
* HP Laserjet 1012 - 4 messages, 4 authors
http://groups.google.com/group/sci.electronics.repair/t/a05ab2facc590cfe?hl=en
* Where to find (affordable) Oven Set Control G.E. - 1 messages, 1 author
http://groups.google.com/group/sci.electronics.repair/t/1cb36c021a0afb59?hl=en
* CD optical block shorting links - 1 messages, 1 author
http://groups.google.com/group/sci.electronics.repair/t/c6b70c559f40bbab?hl=en
* Basic questions about telecommunications - 10 messages, 4 authors
http://groups.google.com/group/sci.electronics.repair/t/86ac7da2cbac660c?hl=en

==============================================================================
TOPIC: LCD display on exercize bike troubleshooting.
http://groups.google.com/group/sci.electronics.repair/t/eb9e9b51f65d17e8?hl=en
==============================================================================

== 1 of 4 ==
Date: Thurs, Dec 30 2010 10:19 pm
From: "Steevo@my-deja.com"


On Thu, 30 Dec 2010 20:45:41 -0600, Jim Yanik <jyanik@abuse.gov>
wrote:
>"Steevo@my-deja.com" <steevo@my-deja.com> wrote in
>news:98dph6d0d3oquccn9k1onongcbdudq5u0m@4ax.com:
>
>If the display "works",but it's light,the drivers are probably OK.
>It might be a bad Vcc regulator IC.

I don't see an obvious regulator IC, or anything that looks to be
power supply, really. This is a cheaply made chinese board, one ic
under a glob of epoxy connected directly to the LCD. Lots of diodes
and caps. No obvious stuff for making the LCD work, seems integrated
in the one ASIC.

>>
>> It seems unlikely to me that this is actually repairable since the
>> large LCD display probably has integrated drivers in it's module. But
>> I haven't disassembled it yet.
>>
>> Is there going to be a whole bunch of driver chips along the edge of
>> the LCD and something that runs those that has failed shorted?
>>
>> What should I be looking into?
>>
>>
>
>perhaps bad electrolytic caps? they can be a common failure.
>do you have an ESR tester,such as the ANATEK/Dick Smith model?

Only three electrolytic caps on the board. I tested them with an
EDS-88A cap tester. They seem OK.

So I dunno.


== 2 of 4 ==
Date: Fri, Dec 31 2010 5:55 am
From: "William Sommerwerck"


> While I had the LCD out I tried it on the board a little moved
> it around. It has those rubber conductive connections. I did
> get bright flashes on some parts of the display, the word
> "AGE" lit up brightly, so the display works.

Let's apply Sherlock Holmes' rule about eliminating the obvious.

If the display flashes or briefly displays "something", the problem might be
the contacts.

Try carefully cleaning the contacts on the board. You might also try
cleaning the conductive-rubber contacts on the LCD, but this requires using
a lint-free swab, and "rolling" (rather than rubbing) the swab over the
contact surfaces. Be vewy, vewy kehful.


== 3 of 4 ==
Date: Fri, Dec 31 2010 7:43 am
From: "William Sommerwerck"


> Let's apply Sherlock Holmes' rule about eliminating the obvious.

Duh... I meant impossible.


== 4 of 4 ==
Date: Fri, Dec 31 2010 12:16 pm
From: "Wild_Bill"


It's likely that there will be a warm/hot component on the board, where the
majority of the current is being dissipated.
That may indicate the vicinity of the fault.

If you power the circuit on for 5-10 seconds (with good batteries or AC/DC
adapter) then power the circuit off (disconnect the AC/DC adapter), you may
be able to detect a heated component with your fingertips.
A longer power cycle may be needed, but avoiding excess on-time may be
beneficial.

I only mention this method for this low voltage, battery powered circuit,
because there is essentially zero chance of any electrical shock hazard with
the power turned off, after a brief power-on period.

Feeling around for warm components on any line powered equipment circuit
boards could very likely be hazardous, even with the power off, and should
not be done as a troubleshooting method.

There is a plastic sheet product that indicates thermal changes, but I don't
remember what it's called. The sheet is placed on a circuit board, and warm
areas change color.

If you know anyone with a thermal/Flir scanner-camera, it would likely show
a heated component on the board.

I doubt that an infrared sensitive surveillance-type video camera would be
sensitive enough to spot heated components with, but if you have access to
one, it may be worth a try, with the test area lighting turned off.

--
Cheers,
WB
.............


"Steevo@my-deja.com" <steevo@my-deja.com> wrote in message
news:98dph6d0d3oquccn9k1onongcbdudq5u0m@4ax.com...
> Sorry if this type of problem has been discussed before, I didn't find
> any useful usenet search of this newsgroup history. Boy, do I miss
> DejaNews! If someone knows of a usable search of
> sci.electronics.repair please post it. The google one was pretty
> terrible IMHO.
>
> I have a "computer" on a Schwinn exercise bike that the monochrome LCD
> is nearly blank. I can see that it is working, but the display is
> very light. When I turn it on I can hear the friction control motor
> in the bottom of the bike working. That system does seem to work, I
> can increase the friction with the buttons on the computer. So
> buttons work, display works a little, other functions work.
>
> A single failure in the display circuitry. The problem is just the
> display.
>
> This runs on 4 C cell batteries, I did check the voltage on the
> batteries and when I press the soft "start" button on the panel the
> battery voltage diminishes from over 6V to less than 1V. Something is
> dragging it down!
>
> I unplugged the harness from the computer to the rest of the bike,
> that didn't change anything. So the short is likely in the computer
> related to the LCD display.
>
> Do the driver chips for such a display fail shorted? That seems to be
> what I have here.
>
> It seems unlikely to me that this is actually repairable since the
> large LCD display probably has integrated drivers in it's module. But
> I haven't disassembled it yet.
>
> Is there going to be a whole bunch of driver chips along the edge of
> the LCD and something that runs those that has failed shorted?
>
> What should I be looking into?
>


==============================================================================
TOPIC: Tapco Juice J 2500 slave amp, 2007
http://groups.google.com/group/sci.electronics.repair/t/185ab3fdb182c05a?hl=en
==============================================================================

== 1 of 3 ==
Date: Fri, Dec 31 2010 4:51 am
From: "N_Cook"


Anyone fmiliar with these ? One ch down but nothing visibly or rhinally
amiss inside. Not powered up at all , just cold exploring at the moment.
Is there output relays lurking under the main board? Triac crowbar ccts on
the o/ps ?


== 2 of 3 ==
Date: Fri, Dec 31 2010 6:57 am
From: "N_Cook"


Would any Mackie amp be similar?
Comes apart easier than it looks, not one large board, 2 sparated pcb and
heatsinks. Still nothing seen amiss so presumably false protection, at least
no microcontroller seen. Plenty of SM under the pcbs but analogue seemingly.


== 3 of 3 ==
Date: Fri, Dec 31 2010 7:56 am
From: "N_Cook"


Hopefully Mackie M 1400 will be similar enough , NJM13700 and LM311 instead
of LM338 for muting and supervision

==============================================================================
TOPIC: american beer inferier?
http://groups.google.com/group/sci.electronics.repair/t/79cf21563e25cfa2?hl=en
==============================================================================

== 1 of 2 ==
Date: Fri, Dec 31 2010 5:02 am
From: "Arfa Daily"


"Lumpy" <lumpy@digitalcartography.com> wrote in message
news:8o045gFl38U1@mid.individual.net...
> Michael A. Terrell wrote:
>
>> Come back when you grow up.
>
> For the last time, I'm not short.
> I just have a tremendously long penis
> and I look short in comparison.
>
>
> Lumpy


I once worked with a guy of whom that was literally true. He and his missus
were both nudists, and his 'wedding photos' were of the both of them on a
beach. There was a set of footprints and a trench leading to where he was
standing ... Actually, he was quite short, but even so ... :-)

Arfa

== 2 of 2 ==
Date: Fri, Dec 31 2010 7:22 am
From: Don Lancaster


On 12/28/2010 11:52 PM, Lumpy wrote:
> Michael A. Terrell wrote:
>
>> Come back when you grow up.
>
> For the last time, I'm not short.
> I just have a tremendously long penis
> and I look short in comparison.
>
>
> Lumpy
>
> You Played on Lawrence Welk?
> Yes but no blue notes. Just blue hairs.
>
> www.LumpyMusic.com
>
>


Its twelve inches long.

But as a rule, he seldom uses it.

--
Many thanks,

Don Lancaster voice phone: (928)428-4073
Synergetics 3860 West First Street Box 809 Thatcher, AZ 85552
rss: http://www.tinaja.com/whtnu.xml email: don@tinaja.com

Please visit my GURU's LAIR web site at http://www.tinaja.com

==============================================================================
TOPIC: HP Laserjet 1012
http://groups.google.com/group/sci.electronics.repair/t/a05ab2facc590cfe?hl=en
==============================================================================

== 1 of 4 ==
Date: Fri, Dec 31 2010 7:40 am
From: Baron


John Keiser Inscribed thus:

> I acquired 3 of these units and they have gotten light use [less than
> 3,000
> pages each]. 1 unit "squeaks" when feeding paper but I thought I'd be
> able to swap parts if needed one day.
> Recently, one unit started to consistently jam with the paper about
> 1/4 inch into the fuser area.
> Not feeding multiple pages so I think the separator pad is fine.
> I say 1/4 inch because when the page is extracted, there is a slight
> crease about 1/4 inch across the top.
> Sometimes I can get 10 pages through OK, but after its warmed up,
> maybe only 1 or 2.
> I changed the cartridge. No joy.
> I thought I'd swap the fuser units but first I tried the "squeaky"
> printer. Prints fine but exactly the same jam.
> I have the service manual and can take these part easily. But the
> manual isn't giving me a good clue as to the issue.
> Could be a timing issue but there aren't many sensors and the manual
> says sensors rarely fail.
> Anyone with experience able to focus me on the cause of the jam?
> Thanks.

On some machines the rubber on the drive roller detaches and migrates to
one end and then fouls the metalwork causing creases and jams.

--
Best Regards:
Baron.


== 2 of 4 ==
Date: Fri, Dec 31 2010 7:42 am
From: "John Keiser"


Separator Pad[s]!


"John Keiser" <john.keiser2@hawaiiantel.net> wrote in message
news:foqdnW82tZF80IDQnZ2dnUVZ_rWdnZ2d@powerusenet.com...
>I acquired 3 of these units and they have gotten light use [less than 3,000
>pages each]. 1 unit "squeaks" when feeding paper but I thought I'd be able
>to swap parts if needed one day.
> Recently, one unit started to consistently jam with the paper about 1/4
> inch into the fuser area.
> Not feeding multiple pages so I think the separator pad is fine.
> I say 1/4 inch because when the page is extracted, there is a slight
> crease about 1/4 inch across the top.
> Sometimes I can get 10 pages through OK, but after its warmed up, maybe
> only 1 or 2.
> I changed the cartridge. No joy.
> I thought I'd swap the fuser units but first I tried the "squeaky"
> printer. Prints fine but exactly the same jam.
> I have the service manual and can take these part easily. But the manual
> isn't giving me a good clue as to the issue.
> Could be a timing issue but there aren't many sensors and the manual says
> sensors rarely fail.
> Anyone with experience able to focus me on the cause of the jam?
> Thanks.
>
>
>
>
>


== 3 of 4 ==
Date: Fri, Dec 31 2010 10:57 am
From: Jeff Liebermann


On Thu, 30 Dec 2010 17:28:25 -1000, "John Keiser"
<john.keiser2@hawaiiantel.net> wrote:

>I acquired 3 of these units and they have gotten light use [less than 3,000
>pages each]. 1 unit "squeaks" when feeding paper but I thought I'd be able
>to swap parts if needed one day.

They all squeak when printing. Plastic against plastic will
eventually squeak. The toner is basically plastic and will imbed
itself into the nylon gears. Cleaning and grease helps, for a while.
You can find the source of the squeaks with a stethoscope or a vinyl
hose stuck in one ear and the other end for sniffing around the gears.

<http://www.fixyourownprinter.com>
Try asking in the forum area.

>Recently, one unit started to consistently jam with the paper about 1/4 inch
>into the fuser area.

The paper feed assumes that both feed rollers are feeding equally and
evenly. If one of them starts to slip, or is a slightly different
diameter, the paper will enter the laser area slightly sideways and
eventually jam. Clean or preferably replace feed rollers if feeding
even slightly sideways.

>Not feeding multiple pages so I think the separator pad is fine.
>I say 1/4 inch because when the page is extracted, there is a slight crease
>about 1/4 inch across the top.
>Sometimes I can get 10 pages through OK, but after its warmed up, maybe only
>1 or 2.

That doesn't sound like the rollers. My next guess would be that
fuser film in the fuser roller assembly is shredded and catching the
edge of the page. This looks close:
<http://www.fixyourownprinter.com/forums/printer/59152>

>I changed the cartridge. No joy.
>I thought I'd swap the fuser units but first I tried the "squeaky" printer.
>Prints fine but exactly the same jam.

I can't tell from your description what you thought of doing or what
you actually did. If you swapped fuser assemblies, and the problem
stayed with the printer, then it's not the fuser. this is not an easy
project.

>I have the service manual and can take these part easily.

The HP LaserJet 1012 is a PITA to take apart and repair. I don't
think it was made to be disassembled. I have two that are about to go
to the recyclers (dead PCB sensors or both).

>But the manual
>isn't giving me a good clue as to the issue.
>Could be a timing issue but there aren't many sensors and the manual says
>sensors rarely fail.

Sensors don't fail. Instead they get filled with toner, dirt, dust,
and in my case, drywall dust. Lots of ways to kill a printer.

>Anyone with experience able to focus me on the cause of the jam?
>Thanks.

It helps to have the plastic side panels removed so you can watch the
gears move. A broken tooth might cause the same problem.
--
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


== 4 of 4 ==
Date: Fri, Dec 31 2010 8:59 pm
From: "Ron D."


Anything blue is meant to be replaced. The paper pickup rollers are
the first suspect. I don't know that printer, but the release
mechanism for most rollers is difficult if you havn't seen how to
release them. Usually that roller wears asymetricly causing the paper
to feed at a slight angle or the paper fails to pick-up.

SOMETIMES you can turn the paper upside down and the printer won't jam
because the curl of the paper is different, but it usually means it
won't last long.

==============================================================================
TOPIC: Where to find (affordable) Oven Set Control G.E.
http://groups.google.com/group/sci.electronics.repair/t/1cb36c021a0afb59?hl=en
==============================================================================

== 1 of 1 ==
Date: Fri, Dec 31 2010 10:46 am
From: Vacillator


Thanks. Do you mean "electrolytic capacitor" ? What do they look
like? I should mention that I accidentally shorted out the bake
element a few years ago, after which I had to switch the thermo to
"clean" to get the red light to go off when the oven selector was in
"off". Otherwise the oven functioned normally. But now I have the
above-mentioned problem, intermittent function of oven selector
switch.

>
> **Before doing anything, look for any electrolytic caps. Replace 'em. That
> solves 90% of electronic oven control problems. Caps are usually rated at
> 125 degrees C or higher and are difficult to obtain though.
>
>
> --
> Trevor Wilson

==============================================================================
TOPIC: CD optical block shorting links
http://groups.google.com/group/sci.electronics.repair/t/c6b70c559f40bbab?hl=en
==============================================================================

== 1 of 1 ==
Date: Fri, Dec 31 2010 11:39 am
From: josephkk


On Thu, 23 Dec 2010 12:22:35 -0000, "N_Cook" <diverse@tcp.co.uk> wrote:

>So what likely went wrong with the laser? Old and new both measure about
>0.65V DVM diode test but powered in circuit the old one was dropping 4.6V
>over the diode and the replacement, working one, about 1.8V across the
>laser.
>

The old laser has ceased to lase, though damaged ones may still emit light
(IR). You old one apparently does not even emit light, thus the high
terminal voltage from the (IR) output regulation circuitry.

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

== 1 of 10 ==
Date: Fri, Dec 31 2010 4:34 pm
From: David Nebenzahl


OK, this question is totally out of idle curiosity. No customers' jobs
depend on it. No actual electronic repair issues are involved.

Like a surprising number of people, I still have dial-up Internet
access. (Yeah, I know, I'm living in the Stone Age.) So I'm quite
familiar with various connections speeds. I also can observe my network
traffic on my firewall's control panel (I use Sygate, a freebie, which
I'm quite happy with).

What I don't understand is why network traffic, at least as reported by
Sygate, is so choppy. On a good day, I get a "fast" connection, meaning
48 kbps, or maybe even (gasp!) 49.2; that's the fastest speed I ever get.

What I see, invariably, is something like a triangular waveform, with a
period of about a second, where the transmission speed varies from
(usually) 4.4 and 5.9 K (I assume this is bytes, not bits, per second,
but whatever). The speeds never change, at least not much. With a faster
connection, it just stays at the higher speed longer, which flattens out
the peaks of the "waveform".

Why is this? I remember hearing that sending packets down a telephone
wire is a "bursty" business; is that part of it?

Why doesn't the connection just stay at one speed? Why does it alternate
between these two speeds?

Of course, this behavior is only when a single download is being done.
If I'm loading a bunch of web pages and reading Usenet, the "waveform"
becomes very chaotic. But it always seems to be alternating between
various speeds.

Not being an expert on such arcane things as packets and such, I can
only guess that this is kind of like quantum physics, were electrons are
only "allowed" to orbit at certain distances from the nucleus. Is there
a set of standard, agreed-upon telecomm speeds? But why not just pick
one speed and stay there?

Maybe next time I'll ask about how I can get a good, fast connection but
not be able to do anything because DNS isn't working ...


NOTE: Please don't ask me to "Google it"! I post this here intentionally
because I know there must be smart people out there who might be able to
shed some light on the subject. Like I said, idle curiosity, and I'm too
lazy to try to sort through the thousands of pages returned by a search,
weed out the commercial sites, the bogus domain-squatters and
web-scrapers, to get to some good "content" ...


--
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.


== 2 of 10 ==
Date: Fri, Dec 31 2010 5:22 pm
From: dplatt@radagast.org (Dave Platt)

In article <4d1e768e$0$32417$822641b3@news.adtechcomputers.com>,
David Nebenzahl <nobody@but.us.chickens> wrote:

>OK, this question is totally out of idle curiosity. No customers' jobs
>depend on it. No actual electronic repair issues are involved.
>
>Like a surprising number of people, I still have dial-up Internet
>access. (Yeah, I know, I'm living in the Stone Age.) So I'm quite
>familiar with various connections speeds. I also can observe my network
>traffic on my firewall's control panel (I use Sygate, a freebie, which
>I'm quite happy with).
>
>What I don't understand is why network traffic, at least as reported by
>Sygate, is so choppy. On a good day, I get a "fast" connection, meaning
>48 kbps, or maybe even (gasp!) 49.2; that's the fastest speed I ever get.
>
>What I see, invariably, is something like a triangular waveform, with a
>period of about a second, where the transmission speed varies from
>(usually) 4.4 and 5.9 K (I assume this is bytes, not bits, per second,
>but whatever). The speeds never change, at least not much. With a faster
>connection, it just stays at the higher speed longer, which flattens out
>the peaks of the "waveform".
>
>Why is this? I remember hearing that sending packets down a telephone
>wire is a "bursty" business; is that part of it?

There are several aspects to the communication process which can cause
this sort of "burstiness".

One is the phone line itself (the modem-to-modem transmission). Modem
connections these days usually use V.42 error correction technology.
The data being sent is broken up into frames or packets (which may
have separation points that have nothing to do with the underlying
TCP/IP packets). The receiving modem will validate a checksum or CRC
on each frame, and if it's bad (e.g. as the result of some line noise,
corrupting a bit in in the frame) the modem will request that its peer
retransmit the entire frame. The data won't be delivered from the
modem to your PC until it has been successfully received (with the
correct CRC) and you'll observe a brief "stutter" in reception
during each such error-correction... often followed by a burst of
rapidly-delivered data, as those frames which were in transit behind
the damaged one are delivered almost instantly.

TCP is also a burst-prone technology. The sending system will
gradually increase the rate at which it transmits packets (and the
number of packets it transmits without waiting for an acknowledgement)
until something goes "sproing" (that is, a packet is lost due to
errors, or discarded because some router in the path decides that its
buffers are full). The loss of a packet causes the receiving system
to send back a "Hunh? Please resent", or to not send back an
acknowledgement... and these will require retransmission of the lost
packet. Net result is that the net transmission speed varies, as a
result of packet loss and network congestion levels.

--
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!


== 3 of 10 ==
Date: Fri, Dec 31 2010 5:30 pm
From: John Tserkezis


David Nebenzahl wrote:

> What I see, invariably, is something like a triangular waveform, with a
> period of about a second, where the transmission speed varies from
> (usually) 4.4 and 5.9 K (I assume this is bytes, not bits, per second,
> but whatever). The speeds never change, at least not much. With a faster
> connection, it just stays at the higher speed longer, which flattens out
> the peaks of the "waveform".

There's a million reasons why speed varies.

It could be line noise, where the modem continually re-negotiates for
the best speed it can.

It could be an iffy line connection, where it works "perfectly" at
lower speeds, so the modem re-negotiates for a higher speed where it
(consistently) fails and falls back again.

It's a bit hard to diagnose this type of problem, more so if you have
modem that does not have good diagnostic feedback on the last call.

If it *IS* noise or line limitations, it might help to force your modem
to 14.4, and see how your connection speed goes. You're looking at
consistency rather than raw speed in this case.

If it IS stable, your line might be going through a pair gain, used by
Telstra to double up on a single copper pair, and splitting up when it
gets near your place. It saves copper wire when they have many
subscribers, plenty of nodes at the exchange, but little copper.

If this is the case, you'll see phone calls work well (albeit sometimes
with crosstalk), Fax works well (9600/14.4) and plays merry hell with
modems that go faster than that.

Good luck with convincing them to fix it though. Even if they DO have
copper to spare, it ends up being a significant resource waster for one
guy who's whining about his modem.
Doesn't hurt to whine though, you might get lucky.

Another option is that it has nothing to do with you or your carrier,
but with your ISP. I've seen bodgy speed throttling techniques that
don't work as well as they should. Though that said, they shouldn't be
going through that anyway, as the modems have inherent speed limitations
to keep them happy anyway.
--
I have a speech impediment... my foot.


== 4 of 10 ==
Date: Fri, Dec 31 2010 6:14 pm
From: David Nebenzahl


On 12/31/2010 5:30 PM John Tserkezis spake thus:

> David Nebenzahl wrote:
>
>> What I see, invariably, is something like a triangular waveform, with a
>> period of about a second, where the transmission speed varies from
>> (usually) 4.4 and 5.9 K (I assume this is bytes, not bits, per second,
>> but whatever). The speeds never change, at least not much. With a faster
>> connection, it just stays at the higher speed longer, which flattens out
>> the peaks of the "waveform".
>
> There's a million reasons why speed varies.
>
> It could be line noise, where the modem continually re-negotiates for
> the best speed it can.
>
> It could be an iffy line connection, where it works "perfectly" at
> lower speeds, so the modem re-negotiates for a higher speed where it
> (consistently) fails and falls back again.
>
> It's a bit hard to diagnose this type of problem, more so if you have
> modem that does not have good diagnostic feedback on the last call.
>
> If it *IS* noise or line limitations, it might help to force your modem
> to 14.4, and see how your connection speed goes. You're looking at
> consistency rather than raw speed in this case.

Thanks for your reply. However, I'm not really reporting or trying to
fix a problem here. I think my connection, for the most part, works
fine. (Actually, there is an easy fix for my problem: $$$.)

I'm just trying to understand *why* it works that way (speed constantly
bouncing between two "notches"). It seems like it's *supposed* to work
that way; why?

I was also going to say something about how it might have something to
do with the negotiation process between client and host, the "REQ/ACK"
process or the equivalent. Not knowing the details of TCP and all that,
I can only guess at what this mechanism is.

Details. I want the gory details.


--
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.


== 5 of 10 ==
Date: Fri, Dec 31 2010 6:57 pm
From: D Yuniskis


Hi David,

On 12/31/2010 5:34 PM, David Nebenzahl wrote:
> What I don't understand is why network traffic, at least as reported by
> Sygate, is so choppy. On a good day, I get a "fast" connection, meaning
> 48 kbps, or maybe even (gasp!) 49.2; that's the fastest speed I ever get.
>
> What I see, invariably, is something like a triangular waveform, with a
> period of about a second, where the transmission speed varies from
> (usually) 4.4 and 5.9 K (I assume this is bytes, not bits, per second,
> but whatever). The speeds never change, at least not much. With a faster
> connection, it just stays at the higher speed longer, which flattens out
> the peaks of the "waveform".

*What* is being reported -- the number of bytes (bits) per second
leaving some "upper level" of network software? Or, the actual
speed that the *modem* is operating at? (I suspect the former
unless your tool knows how to query *your* modem, directly,
for this information).

So, you have some process in the PC that starts and stops
sending bytes to the modem. The modem probably has a buffer
(even if it is a software modem *in* your PC) that it fills
up with bytes "from" your PC... then, empties into the phone
line... lather, rinse, repeat.

The modem typically doesn't signal the PC after *each*
byte has been pushed out onto the phone line -- that
would involve too much overhead on both sides. Instead,
it imposes a certain amount of hysteresis on the "signaling".
So, a 100 byte buffer says "Full" when it receives it's 100th
byte from the PC.... but, doesn't say "not full" until it
has pushed maybe 80 of those bytes out onto the phone line.

I.e., on a very short time scale, it looks (from the PC's
point of view) like the modem is operating VERY FAST
(gee, it gobbled up those 100 bytes in less than a millisecond)
then very slow (gee, it hasn't asked for ANY more data for
dozens of milliseconds).

(No, this isn't your "problem". Rather, just an example of how
things aren't "continuous time systems" when it comes to this
sort of thing).

Modern modems autonegotiate connection speeds -- based on the
capabilities of the two modems talking to each other *and*
the line conditions in effect from moment to moment.

The connection speed is sort of like the "carrier frequency"
(I am grossly misstating things here just to give you an analogy)
of your local radio station. Your receiver has to be "tuned"
to the same frequency as the transmitter for reception to occur.
The two modems do this continuously while communicating.

ON TOP OF that "carrier", you have your actual data rate.
To further push the radio broadcast analogy, that's like
the rate at which the announcer is talking -- someone who
talks slow vs. someone who talks fast.

[again, this is REALLY a bogus analogy]

The system at the other end of the line (and there can be
several of them cascaded, in effect) can throttle the
data flow. E.g., there is something like the output
buffer of *your* modem on the other end acting as an
"input buffer". It fills and empties in non-continuous
ways based on what *it* is talking to.

Etc.

You can also have underlying "infrastructure" that further
distorts these numbers. E.g., the presence of a SLIC96
can limit available bandwidth (though usually to something
a lot less than what you appear to be seeing) simply because
*it* has a limited bandwidth capability that it imposes
on the lines that it services.

Speeds upwards of 33.6Kbps tend to be more sensitive to line
noise, distance from CO, etc.

You could also have a really noisey line and the noise might
come and go "periodically" -- forcing the modem(s) to change
speeds and/or request retransmissions "regularly".

<shrug> It's really hard to say what you are experiencing without
actually looking at your line. As a starting point, you can see
if you can query your modem for statistics about the last call,
etc. (doing so varies by model, etc.)

> Why is this? I remember hearing that sending packets down a telephone
> wire is a "bursty" business; is that part of it?
>
> Why doesn't the connection just stay at one speed? Why does it alternate
> between these two speeds?
>
> Of course, this behavior is only when a single download is being done.
> If I'm loading a bunch of web pages and reading Usenet, the "waveform"
> becomes very chaotic. But it always seems to be alternating between
> various speeds.
>
> Not being an expert on such arcane things as packets and such, I can
> only guess that this is kind of like quantum physics, were electrons are
> only "allowed" to orbit at certain distances from the nucleus. Is there
> a set of standard, agreed-upon telecomm speeds? But why not just pick
> one speed and stay there?
>
> Maybe next time I'll ask about how I can get a good, fast connection but
> not be able to do anything because DNS isn't working ...

Hint: make a note of the IP addresses of various "stable" sites.
When your name resolver isn't working, you can use these numeric
IP addresses to verify that the problem is, in fact, with the
name service and not "The Network".

IIRC, there are some public sites that will provide a *manual*
name service that you could use in a pinch (assuming you
keep a record of their NUMERIC IP addresses)

> NOTE: Please don't ask me to "Google it"! I post this here intentionally
> because I know there must be smart people out there who might be able to
> shed some light on the subject. Like I said, idle curiosity, and I'm too
> lazy to try to sort through the thousands of pages returned by a search,
> weed out the commercial sites, the bogus domain-squatters and
> web-scrapers, to get to some good "content" ...

== 6 of 10 ==
Date: Fri, Dec 31 2010 6:53 pm
From: John Tserkezis


David Nebenzahl wrote:

> Thanks for your reply. However, I'm not really reporting or trying to
> fix a problem here. I think my connection, for the most part, works
> fine. (Actually, there is an easy fix for my problem: $$$.)

> I'm just trying to understand *why* it works that way (speed constantly
> bouncing between two "notches"). It seems like it's *supposed* to work
> that way; why?

> I was also going to say something about how it might have something to
> do with the negotiation process between client and host, the "REQ/ACK"
> process or the equivalent. Not knowing the details of TCP and all that,
> I can only guess at what this mechanism is.

I didn't entertain the packetising of data, because that is faster than
the graph logging anyway, so you shouldn't even see it.

Besides, from what I remember of modem links, it never behaved that way
anyway, by the time the speed graph showed anything of interest, it was
reasonably steady.

What's the timing of your graph anyway? How frequently does it take a
sample?
--
I'm not opinionated, I'm just always right!


== 7 of 10 ==
Date: Fri, Dec 31 2010 7:04 pm
From: David Nebenzahl


On 12/31/2010 6:53 PM John Tserkezis spake thus:

> David Nebenzahl wrote:
>
>> Thanks for your reply. However, I'm not really reporting or trying to
>> fix a problem here. I think my connection, for the most part, works
>> fine. (Actually, there is an easy fix for my problem: $$$.)
>
>> I'm just trying to understand *why* it works that way (speed constantly
>> bouncing between two "notches"). It seems like it's *supposed* to work
>> that way; why?
>
>> I was also going to say something about how it might have something to
>> do with the negotiation process between client and host, the "REQ/ACK"
>> process or the equivalent. Not knowing the details of TCP and all that,
>> I can only guess at what this mechanism is.
>
> I didn't entertain the packetising of data, because that is faster than
> the graph logging anyway, so you shouldn't even see it.
>
> Besides, from what I remember of modem links, it never behaved that way
> anyway, by the time the speed graph showed anything of interest, it was
> reasonably steady.
>
> What's the timing of your graph anyway? How frequently does it take a
> sample?

As I said, period seems to be about a second. The only time I see a
straight line is if I upload something. I think FTP transfers are a lot
more steady as well. Otherwise, the transfer speed (incoming) is
constantly changing.

I could post a snapshot if you like.

Doesn't seem to be anything wrong with the modem, the phone line or the
system. It just likes to behave that way.


--
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.


== 8 of 10 ==
Date: Fri, Dec 31 2010 7:24 pm
From: John Tserkezis


David Nebenzahl wrote:

> As I said, period seems to be about a second. The only time I see a
> straight line is if I upload something. I think FTP transfers are a lot
> more steady as well. Otherwise, the transfer speed (incoming) is
> constantly changing.

> I could post a snapshot if you like.

Sure, I'd like to see the timing.
--
Never draw fire, it irritates everyone around you


== 9 of 10 ==
Date: Fri, Dec 31 2010 7:32 pm
From: David Nebenzahl


On 12/31/2010 7:24 PM John Tserkezis spake thus:

> David Nebenzahl wrote:
>
>> As I said, period seems to be about a second. The only time I see a
>> straight line is if I upload something. I think FTP transfers are a lot
>> more steady as well. Otherwise, the transfer speed (incoming) is
>> constantly changing.
>
>> I could post a snapshot if you like.
>
> Sure, I'd like to see the timing.

Here:
http://s786.photobucket.com/albums/yy147/bonezphoto/?action=view&current=Linespeeds.gif

Time divisions are ~3 seconds. This transfer (downloading a picture)
bounced between 3.0 and 4.4 K (which I ass-ume means kilobytes?).

On longer transfers the pattern (sawtooth "wave") becomes very regular.


--
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.


== 10 of 10 ==
Date: Fri, Dec 31 2010 8:39 pm
From: John Tserkezis


David Nebenzahl wrote:

> Here:
> http://s786.photobucket.com/albums/yy147/bonezphoto/?action=view&current=Linespeeds.gif

> Time divisions are ~3 seconds. This transfer (downloading a picture)
> bounced between 3.0 and 4.4 K (which I ass-ume means kilobytes?).

> On longer transfers the pattern (sawtooth "wave") becomes very regular.

OK, you're talking about 9 seconds or so between each drop and rise,
that's not a protocol issue, it's way too long. It might be a
re-negotiation timing, or something your ISP is doing.
--
What does Santa do at a house with no chimney?


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sci.electronics.repair - 7 new messages in 5 topics - digest

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TOPIC: HP Laserjet 1012
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== 1 of 2 ==
Date: Thurs, Dec 30 2010 7:28 pm
From: "John Keiser"


I acquired 3 of these units and they have gotten light use [less than 3,000
pages each]. 1 unit "squeaks" when feeding paper but I thought I'd be able
to swap parts if needed one day.
Recently, one unit started to consistently jam with the paper about 1/4 inch
into the fuser area.
Not feeding multiple pages so I think the separator pad is fine.
I say 1/4 inch because when the page is extracted, there is a slight crease
about 1/4 inch across the top.
Sometimes I can get 10 pages through OK, but after its warmed up, maybe only
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I changed the cartridge. No joy.
I thought I'd swap the fuser units but first I tried the "squeaky" printer.
Prints fine but exactly the same jam.
I have the service manual and can take these part easily. But the manual
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Could be a timing issue but there aren't many sensors and the manual says
sensors rarely fail.
Anyone with experience able to focus me on the cause of the jam?
Thanks.



== 2 of 2 ==
Date: Thurs, Dec 30 2010 7:39 pm
From: Allodoxaphobia


On Thu, 30 Dec 2010 17:28:25 -1000, John Keiser wrote:
> I acquired 3 of these units and they have gotten light use [less than 3,000
> pages each]. 1 unit "squeaks" when feeding paper but I thought I'd be able
> to swap parts if needed one day.
> Recently, one unit started to consistently jam with the paper about 1/4 inch
> into the fuser area.

Try also:

comp.sys.hp.hardware
comp.periphs.printers

Jonesy

==============================================================================
TOPIC: LCD display on exercize bike troubleshooting.
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==============================================================================

== 1 of 2 ==
Date: Thurs, Dec 30 2010 8:17 pm
From: D Yuniskis


On 12/30/2010 2:55 PM, Steevo wrote:
> "Charlie"<left@thestation.com> wrote in message
> news:ifimmi$h80$1@news.eternal-september.org...
>>> Before you get all tangled up, try a set of NEW batteries.
>> If you are testing with a digital meter you are putting essentially no
>> load on the batteries.
>> Where in the circuit did you access the voltage reading?
>> If the batteries are truly good, just probe along the connections from the
>> batteries to the display to find the high resistance culprit.
>>
>>
>> Charlie
>
> I did test at the battery contacts in circuit.
> They are new batteries.
> I could try some other new batteries but I suspect these batteries should
> work.
> That said I did plug in an ac adapter, 6v 2A, and it acts the same with or
> without the batteries installed.

So, it's drawing (considerably) *more* than 2A (in order to
drag the 6V supply down to 1V)? What exactly *is* it
drawing?


== 2 of 2 ==
Date: Thurs, Dec 30 2010 10:19 pm
From: "Steevo@my-deja.com"


On Thu, 30 Dec 2010 20:45:41 -0600, Jim Yanik <jyanik@abuse.gov>
wrote:
>"Steevo@my-deja.com" <steevo@my-deja.com> wrote in
>news:98dph6d0d3oquccn9k1onongcbdudq5u0m@4ax.com:
>
>If the display "works",but it's light,the drivers are probably OK.
>It might be a bad Vcc regulator IC.

I don't see an obvious regulator IC, or anything that looks to be
power supply, really. This is a cheaply made chinese board, one ic
under a glob of epoxy connected directly to the LCD. Lots of diodes
and caps. No obvious stuff for making the LCD work, seems integrated
in the one ASIC.

>>
>> It seems unlikely to me that this is actually repairable since the
>> large LCD display probably has integrated drivers in it's module. But
>> I haven't disassembled it yet.
>>
>> Is there going to be a whole bunch of driver chips along the edge of
>> the LCD and something that runs those that has failed shorted?
>>
>> What should I be looking into?
>>
>>
>
>perhaps bad electrolytic caps? they can be a common failure.
>do you have an ESR tester,such as the ANATEK/Dick Smith model?

Only three electrolytic caps on the board. I tested them with an
EDS-88A cap tester. They seem OK.

So I dunno.

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