Digest for sci.electronics.repair@googlegroups.com - 25 updates in 6 topics

JW <none@dev.null>: Aug 25 11:12AM -0400

On Wed, 24 Aug 2016 13:05:43 -0700 (PDT) whit3rd <whit3rd@gmail.com> wrote
>WiFi user (or other device in the 2.4 GHz band) its broadcast could swamp
>yours, except for pauses between transfers.
 
>Signal strength might be excellent, but the road is crowded.
 
Thanks, I don't think it's that given the symptoms (requires power cycle)
JW <none@dev.null>: Aug 25 11:11AM -0400

On Thu, 25 Aug 2016 06:07:24 -0700 (PDT) jack4747@gmail.com wrote in
>> http://www.linksys.com/us/support-article?articleNum=148629
 
>there are firmware update, just not from Linksys:
 
>http://www.dd-wrt.com/site/index
 
Thanks. Looks like I have already have the last version ever released by
Linksys.
http://dd-wrt.com/wiki/index.php/Linksys_WRT54GS_v2.0
Jeff Liebermann <jeffl@cruzio.com>: Aug 25 03:27PM -0700


>Happens once a day or so, but sometimes not for several days or more.
>Wired connections work fine.
 
>Firmware version: v4.71.4
 
Current firmware is:
WRT54GS_4.71.4.001_fw,2.bin
<http://www.dd-wrt.com/phpBB2/viewtopic.php?p=643052>
<http://www.dd-wrt.com/phpBB2/download.php?id=20701&sid=e2141ada1089e4d9835e4103538b2801>
 
>to be... Maybe they pulled the plug on this model?
>http://www.linksys.com/us/support-article?articleNum=148629
 
>Thanks.
 
It's been many years since I've seen that phenomenon and it's quite
real. It's a bug in the firmware that runs the radio section. The
problem is that the easily replaceable firmware such as DD-WRT
operates mostly on layer 3, while the wireless card operates on layer
2. For alternative firmware, the layer 2 stuff is supplied by Linksys
in the form of a linkable library that can't be tweaked. This might
be why firmware transplants haven't done anything to fix the problem
and why only some WRT54G and GS v2 boxes have the problem.
 
It's been many years since the WRT54GS was in fashion. There has been
considerable progress in wireless chips, antennas, router features,
acronyms, and aerodynamic packaging. You might want to consider a
newer wireless router.
 
--
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
JW <none@dev.null>: Aug 26 05:23AM -0400

On Thu, 25 Aug 2016 15:27:30 -0700 Jeff Liebermann <jeffl@cruzio.com>
>considerable progress in wireless chips, antennas, router features,
>acronyms, and aerodynamic packaging. You might want to consider a
>newer wireless router.
 
Thank you for that Jeff. I think you may be right. Have any good
reasonably priced recommendations?
"ScottWW" <spamtrap@dcorp.com>: Aug 26 08:31AM -0400


>Thanks. Looks like I have already have the last version ever released by
>Linksys.
>http://dd-wrt.com/wiki/index.php/Linksys_WRT54GS_v2.0
 
I had a WRT54G that required frequent resets right out of the box. The
firmware was up-to-date. Reverting back one version made it much more
stable. Ultimately though, I had to replace it.
Scott
Jeff Liebermann <jeffl@cruzio.com>: Aug 26 08:19AM -0700


>Thank you for that Jeff. I think you may be right. Have any good
>reasonably priced recommendations?
 
Maybe, but I need to know what you're doing with it, the speed of the
internet connection, number of simultaneous connections, and whether
you plan to use alternative firmware. Some clue as to the environment
(business, coffee shop, outdoors, home, industrial, doorstop, etc). Do
you need gigabit ethernet or will 10/100Mbits/sec suffice? USB 2.0,
3.0, or none? What you consider reasonably priced?
 
If you want really cheap, I've been buying refurbished Linksys EA2700
wireless routers from the Belkin (they own Linksys) eBay store:
<http://stores.ebay.com/linksysofficialstore/Wireless-Routers-/_i.html?_sacat=44995>
<http://www.ebay.com/itm/Linksys-N600-Dual-Band-Wi-Fi-Router-Manfacturer-Refurbished-/301761478977>
for $25 including shipping. Can't get much cheaper than that for a
dual band router with gigabit ethernet interface. However, the router
has a few odd problem.
1. The wireless range is lousy.
2. The wall warts blow up after about 2 years of service.
3. I can't stack anything on top of it due to the rounded top.
4. No flashing lights for user diagnostics.
However, wireless speed is good, measured up to 60 Mbits/sec.
<http://802.11junk.com/jeffl/FLUG-talk-2015-02-28/802.11gn%20direct.jpg>
I use these for lighting up small areas that do NOT require going
through walls or covering long distances. I also stock spare power
supplies.
 
For home users, the other end of the scale is an Asus RT-AC68Uv2.
<https://www.asus.com/us/Networking/RTAC68U/>
About $130. I don't care much about the AC speeds, but the range is
much better thanks to three 2.4GHz and three 4GHz power amps inside.
However, I've only installed one of these, and haven't had time to do
any kind of performance analysis. My seat of the pants evaluation is
that I like what I see (except for the price).
<http://www.smallnetbuilder.com/wireless/wireless-reviews/32609-asus-rt-ac68p-dual-band-wireless-ac1900-gigabit-router-reviewed>
<http://www.smallnetbuilder.com/wireless/wireless-reviews/32239-ac1900-first-look-netgear-r7000-a-asus-rt-ac68u>
<http://www.smallnetbuilder.com/tools/router-chooser/detail/1235/asus-rtac68u>
<http://www.smallnetbuilder.com/tools/rankers/router/result/1235-asus-rtac68u>
It's on the DD-WRT supported list:
<http://www.dd-wrt.com/wiki/index.php/Supported_Devices#Asus>
but I haven't tried it yet.
 
Note: I'm a big fan of having the wireless access point(s) seperate
from the router, but cost and complexity prevent me from selling that
to home users.
 
 
--
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
Jeff Liebermann <jeffl@cruzio.com>: Aug 26 08:45AM -0700

On Fri, 26 Aug 2016 08:19:08 -0700, Jeff Liebermann <jeffl@cruzio.com>
wrote:
 
>For home users, the other end of the scale is an Asus RT-AC68Uv2.
><https://www.asus.com/us/Networking/RTAC68U/>
 
Oops. I goofed. That should be for an RT-AC68P, not U.
<http://www.asus.com/Networking/RTAC68P/>
The FCC site has it listed as RT-AC68V2.
<http://www.smallnetbuilder.com/wireless/wireless-reviews/32609-asus-rt-ac68p-dual-band-wireless-ac1900-gigabit-router-reviewed>
 
The links I previously mentioned are all for the V1 router RT-AC68U.
There are some substantial hardware differences between v1 and v2. V1
is an RT-AC68U, while V2 is an RT-AC68P.
<https://wikidevi.com/wiki/ASUS_RT-AC68P>
Some sales web sites are mixing these two with little control over
which one will arrive. Anyway, look for the "P", not "U". This one
worked for me:
<http://www.newegg.com/Product/Product.aspx?Item=N82E16833320228>
Sorry(tm) and caveat emptor.
 
There is also Asus specific alternative firmware available:
<http://asuswrt.lostrealm.ca/about>
I haven't tried it yet.
 
--
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
avagadro7@gmail.com: Aug 25 05:22PM -0700


> want to separate connectors n pull receiver out during sensitive parking.
 
> several dc and 4 stereo connectors if possible with no distortion/loss .
 
> broadcast quality .....
 
no suggestions ?
mike <ham789@netzero.net>: Aug 25 06:47PM -0700


>> several dc and 4 stereo connectors if possible with no distortion/loss .
 
>> broadcast quality .....
 
> no suggestions ?
 
yep,
Go to any car stereo installation store and ask them.
avagadro7@gmail.com: Aug 26 06:09AM -0700

local shop
 
 
goo.gl/b7pC5g
"David Farber" <farberbear.unspam@aol.com>: Aug 25 01:11PM -0700

This Tascam DR-44WL digital recorder was given to me for repair. I asked how
the screen got damaged. The user, a friend of mine, said that it wasn't
dropped or mishandled. It was placed on the floor in an out of a way place
before his band played and 45 minutes later he went to retrieve it and the
screen looked like this:
http://webpages.charter.net/mrfixiter/images/Electronics/Tascam/DR-44WL-screen.jpg
The rest of the unit looks very clean. There are no scratches anywhere.
 
A new screen costs around $40 + shipping but I was curious what kind of
defect would cause an image like this without some severe impact to the
display? If I replace the display, is it likely to happen again? The
recorder has only been used a few times and it's about 18 months old.
 
Thanks for your replies.
--
David Farber
Los Osos, CA
"Gareth Magennis" <soundserviceleeds@outlook.com>: Aug 25 09:29PM +0100

"David Farber" wrote in message news:npnje4$n86$1@dont-email.me...
 
This Tascam DR-44WL digital recorder was given to me for repair. I asked how
the screen got damaged. The user, a friend of mine, said that it wasn't
dropped or mishandled. It was placed on the floor in an out of a way place
before his band played and 45 minutes later he went to retrieve it and the
screen looked like this:
http://webpages.charter.net/mrfixiter/images/Electronics/Tascam/DR-44WL-screen.jpg
The rest of the unit looks very clean. There are no scratches anywhere.
 
A new screen costs around $40 + shipping but I was curious what kind of
defect would cause an image like this without some severe impact to the
display? If I replace the display, is it likely to happen again? The
recorder has only been used a few times and it's about 18 months old.
 
Thanks for your replies.
--
David Farber
Los Osos, CA
 
 
 
 
 
 
Hmm, I suspect a severe impact.
 
 
Gareth.
Adrian Caspersz <email@here.invalid>: Aug 25 09:44PM +0100

On 25/08/16 21:11, David Farber wrote:
> defect would cause an image like this without some severe impact to the
> display? If I replace the display, is it likely to happen again? The
> recorder has only been used a few times and it's about 18 months old.
 
A neighbour gave me their Lenovo laptop to fix that had a cracked
screen. Their kid was pretty insistant it wasn't dropped, but I couldn't
entertain the warranty company with that statement; I don't have a lie
detector that can be plugged into her and ethernet - so we fitted a new
display ourselves.
 
An idea. Extreme heat? Humidity? Electroluminescent panel flashover?
 
--
Adrian C
AL <noemail@none.com>: Aug 25 02:05PM -0700

On 8/25/2016 1:11 PM, David Farber wrote:
> display? If I replace the display, is it likely to happen again? The
> recorder has only been used a few times and it's about 18 months old.
 
> Thanks for your replies.
 
How close was it to the band's woofer? Some of the bands I've heard can
really shake things up. Could the vibration have caused the screen damage?
 
As an aside, years ago when the movie Earthquake first came out the
local theater put large woofers in the rear. So when the earthquake
scene came on the whole place really shook. After several weeks they
actually discovered structural damage to the building and the place had
to close for the repairs.
"David Farber" <farberbear.unspam@aol.com>: Aug 25 03:17PM -0700

AL wrote:
> scene came on the whole place really shook. After several weeks they
> actually discovered structural damage to the building and the place
> had to close for the repairs.
 
This is a rather low key band that plays traditional jazz music.
 
It's amazing a movie could be so loud that it caused structural damage to a
building but not cause hearing damage to the moviegoers!
 
Thanks for your reply.
--
David Farber
Los Osos, CA
dplatt@coop.radagast.org (Dave Platt): Aug 25 03:21PM -0700

>defect would cause an image like this without some severe impact to the
>display? If I replace the display, is it likely to happen again? The
>recorder has only been used a few times and it's about 18 months old.
 
It looks to me as if the edge of the LCD panel was compromised,
allowing an air leak into the panel.
 
This might be due to a manufacturing defect, but the radiating pattern
of lines, and the thin little hairline I see at the tip of the
leftmost radiating spike of blue-ness, suggests that the panel was
actually fractured or chipped at its edge... either by impact or by
excessive non-impact pressure. The whitish spots/rings near the top
of the display area suggest that something has pushed or scraped the
protective cover enough to damage the plastic film.
 
If the recorder was sitting on the floor, is there a possibility that
the place wasn't "out of the way" enough, and somebody accidentally
stepped on it? That might easily flex the plastic cover and put
pressure onto the LCD and crack it. Direct downward pressure by a
shoe might not have left scratches, other than perhaps those small
scrapes/defects just below the top.
"David Farber" <farberbear.unspam@aol.com>: Aug 25 04:12PM -0700

Dave Platt wrote:
> pressure onto the LCD and crack it. Direct downward pressure by a
> shoe might not have left scratches, other than perhaps those small
> scrapes/defects just below the top.
 
Hi Dave,
 
Yes, it is possible that someone or something came in contact with it as it
was out of view for a while. There were quite a few people milling about the
area and who knows what the real story is. Your explanation seems quite
plausible.
 
Thanks for your reply.
--
David Farber
Los Osos, CA
Phil Allison <pallison49@gmail.com>: Aug 25 07:05PM -0700

David Farber wrote:
 
 
> It's amazing a movie could be so loud that it caused structural damage to a
> building but not cause hearing damage to the moviegoers!
 
** The sound was all very low frequency so excited standing waves in the room.
 
The system was developed by speaker maker Cerwin-Vega and called "Sensurround":
 
https://en.wikipedia.org/wiki/Sensurround
 
Cerwin-Vega also supplied high powered amplifiers for the system, mostly models A3000 and A1800 which later turned up on the second hand market and were bought for use in PA systems for live music in the 1980s.
 
One of my customers acquired a number of them and they were constantly coming in for repair. They were never built well enough to go touring in the back of a truck.
 
 
.... Phil
N_Cook <diverse@tcp.co.uk>: Aug 26 08:01AM +0100

On 25/08/2016 21:11, David Farber wrote:
> display? If I replace the display, is it likely to happen again? The
> recorder has only been used a few times and it's about 18 months old.
 
> Thanks for your replies.
 
Before replacing new display, look for grit/swarf etc maybe from
manufacture, then stressing of the case caused point stress crack
isw <isw@witzend.com>: Aug 25 09:45PM -0700

A friend came across one of these, a bit dirty but otherwise looking OK.
Green pilot lights up, but the screen does not, even in a darkened room.
 
Are there well-known failure points in these? Where to find a schematic
and/or service manual?
 
Isaac
"tom" <tmiller11147@verizon.net>: Aug 26 01:28AM -0400

"isw" <isw@witzend.com> wrote in message
news:isw-A34D3E.21452125082016@news-roam.garlic.com...
 
> Are there well-known failure points in these? Where to find a schematic
> and/or service manual?
 
> Isaac
 
Service manual and Operators manual here:
 
http://w140.com/tekwiki/wiki/2235
 
Also you might join the tek yahoo group and describe your findings there.
 
https://groups.yahoo.com/neo/groups/TekScopes/info
 
 
Good luck.
 
--
Bob Simon <bobneworleans@gmail.com>: Aug 25 07:24PM -0700

I recently moved and connected my new Cox Contour DVR to an audio receiver and TV. (A Blu-ray player is also connected to the receiver and TV; this may or may not have any relevance to my issues.) There was a pretty bad hum so I inserted an isolation transformer between the cable feed and the DVR, which eliminated the hum. I measured the voltage between the outside of the cable connector and safety ground with a cheap VOM and found 0.2VAC and 1-9 mVDC. I have a number of questions that I hope someone can answer for me.
 
Is this voltage difference the cause of the hum?
 
Was my measurement approach appropriate?
 
Do the measured voltages indicate that the cable is improperly grounded?
 
If the cable were to be bonded to the house neutral with 3/0AWG, would this likely eliminate the need for the isolation transformer?
 
Whether it would eliminate the hum or not, should I have it done?
 
Does the cable company have any obligation to do it in order to comply with regulations?
 
Bob Simon
New Orleans
stratus46@yahoo.com: Aug 25 10:01PM -0700

On Thursday, August 25, 2016 at 7:24:18 PM UTC-7, Bob Simon wrote:
 
> Does the cable company have any obligation to do it in order to comply with regulations?
 
> Bob Simon
> New Orleans
 
Since the iso transformer got rid of the hum it's a real good bet that the 200mV is your problem. I had a similar problem with tuners in the computers and antenna / cable feeds and hum. A 'galvanic isolator' from these folks cleaned everything up.
 
http://www.rmscommunications.net/mi2120v_n.htm
 
The Voltage in my system is similar to yours so safety really isn't an issue. The isolator solved the problem and as far as I'm concerned, it's a permanent solution.
 

bscs-fa15-080@tuf.edu.pk: Aug 25 02:29PM -0700

dear sir am looking for solutions of this book
would you like to provide me
i'll be very thankfull to you
jurb6006@gmail.com: Aug 25 05:03PM -0700

>" Do you really think that the spammer comes back to look for >replies? "
 
He even said he doesn't. Some people are so stupid, how do they even live ? Someone must be there to remind them to breathe.
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