Digest for sci.electronics.repair@googlegroups.com - 12 updates in 4 topics

jaugustine@verizon.net: Jun 09 02:51PM -0400

Hi,
I am a retired consumer electronics repair tech.
 
Recently, my 14" RCA, (CRT) model 14F512T (mfg. 2006) began turning
itself on, then off.
 
I remember years ago, I had the same issue with a 27" RCA (CRT) model
27V412T doing the exact same thing. I discovered that the on/off power button
switch on the front panel was the cause. Even though the button switch
checked AOK (no "leakage current" between the contacts using a 50V leak test),
I decided to open the circuit so the switch is "disabled". That fixed the
problem. Note: Remote turns the TV on/off.
 
I did the same thing with my 14" RCA TV, and that fixed the problem.
 
John
jurb6006@gmail.com: Jun 09 08:44PM -0700

Hold on - first question :
 
Does it turn itself on with no intervention or do you turn it on and then it turns off and then back on ?
 
This is an important question.
tabbypurr@gmail.com: Jun 09 11:09PM -0700

> Hold on - first question :
 
> Does it turn itself on with no intervention or do you turn it on and then it turns off and then back on ?
 
> This is an important question.
 
TVs like that have been buried in their millions here. You can't give them away.
 
 
NT
amdx <nojunk@knology.net>: Jun 10 07:54AM -0500


>> This is an important question.
 
> TVs like that have been buried in their millions here. You can't give them away.
 
> NT
 
Yep, I recently took a nice 32" CRT Sony to The Salvation Army, they
said they didn't want it. They did allow me to put it in an area for a
guy that picks them up for recycling.
Because it was so heavy, two of us did a slow drop onto a cushion
of the back of my truck.
 
Mikek
The Real Bev <bashley101@gmail.com>: Jun 09 06:13PM -0700

E-reader. Very nice. The other day I fell on it and broke it in some
mysterious way. After the fall the backlight turned on with a
long-press of the appropriate button, but the display would not change
from the standard picture. After a while that stopped working too.
Nothing worked.
 
Took it apart and couldn't see anything obviously broken. A new one is
~$25 on ebay, so buying a $9 battery on spec is silly, especially when I
have a spare from a yard sale.
 
Can anybody speculate on what might be broken?
 
--
Cheers, Bev
In theory there is no difference between theory and practice,
but in practice there is.
whit3rd <whit3rd@gmail.com>: Jun 09 11:41PM -0700

On Saturday, June 9, 2018 at 6:13:48 PM UTC-7, The Real Bev wrote:
> mysterious way. After the fall the backlight turned on with a
> long-press of the appropriate button, but the display would not change
> from the standard picture. After a while that stopped working too.
 
A lot of the interconnections are surface-mount things that wedge
or clamp flexible cables; I've seen those dislodge (or actually break
solder joints) without being obvious. A probe with a stick (I keep chopsticks
in the toolbox) can make it wiggle, if that's the issue.
Jeff Liebermann <jeffl@cruzio.com>: Jun 09 04:59PM -0700


>I want one with continuously variable IF bandwidth on the front.
 
With a DSP filter and demodulator, you can have exactly that. Spin
the shaft encoder knob, and the filter coeficients will change to
whatever you find useful. Not exactly what you want, but close:
 
ATR4255P
<https://media.digikey.com/pdf/Data%20Sheets/Atmel%20PDFs/ATR4255P.pdf>
For improved FM performance, an integrated IF filter with
adjustable bandwidth, a soft mute feature, and an automatic
multipath noise cancellation (MNC) circuit are fully integrated.
A powerful set of sensors is provided for receiving condition
analysis and stop signal generation.
 
 
 
--
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
Phil Allison <pallison49@gmail.com>: Jun 09 06:02PM -0700


> >"Tuners that are beloved of the "FM DX" crowd will tend to have: "
 
> I want one with continuously variable IF bandwidth on the front.
 
** Such a feature is useful with AM reception but not with broadcast FM.
 
The FM signal is inherently wide band, with +/-75 kHz deviation at peak audio level - if the IF bandwidth is less than 150kHz, distorted sound is the result.
 
I have a radio scanner ( AR 1000xlt ) with wide and narrow FM modes, 30kHz and 200kHz respectively. Listening to broadcast FM while in narrow mode is *intolerable*, in wide mode it sounds just fine.
 
 
 
.... Phil
jurb6006@gmail.com: Jun 09 07:21PM -0700

>"** Such a feature is useful with AM reception but not with broadcast FM. "
 
I've had it in a couple of tuners and found it useful when DXing, and once in a great while other times but still DXing somewhat. Listening to strong local stations just leave it in wide though, then it practically worthless.
Phil Allison <pallison49@gmail.com>: Jun 09 07:40PM -0700


>"Tuners that are beloved of the "FM DX" crowd will tend to have: "
 
" I want one with continuously variable IF bandwidth on the front. "
 
 
 
> >"** Such a feature is useful with AM reception but not with broadcast FM. "
 
The FM signal is inherently wide band, with +/-75 kHz deviation at peak audio level - if the IF bandwidth is less than 150kHz, distorted sound is the result.
 
I have a radio scanner ( AR 1000xlt ) with wide and narrow FM modes, 30kHz and 200kHz respectively. Listening to broadcast FM while in narrow mode is *intolerable*, in wide mode it sounds just fine.
 
 
 
 
> I've had it in a couple of tuners and found it useful when DXing,
 
 
** Continuously variable ????
 
Or just a couple of settings.
 
FFS stop oversnipping !!!!
 
 

.... Phil
jurb6006@gmail.com: Jun 09 08:38PM -0700

>"** Continuously variable ???? "
 
Sorry, switchable, narrow and wide. I heard of a tuner with three positions but never had one and don't remember the name or model.
 
Doing variable control in the analog domain would be an incredible bitch but that's how I want it. Actually it only has to be a couple of stages towards the front, maybe even just one, but still. Maybe Studer Revox would do something like this (maybe they have) but I doubt anyone else. Them engineers there I bet are showoffs. I'm not bitching, just saying. I saw the print of one of their tuners and said "WTF, are you sending the first mission to Mars or what here ?". I'm sure I still have it lurking around a drive here but it would probably be easier to find it online again than to look through all my backup.
 
Yes I am a nasty SOB who wants someone else to do what I can't. But they get paid for that.
oldschool@tubes.com: Jun 09 01:18PM -0500

On Fri, 8 Jun 2018 10:13:54 -0400, Phil Hobbs
 
>Blech. Sorry to hear that.
 
>Cheers
 
>Phil Hobbs
 
That GPS with touch screen was viewable at first. Cloudy, but I could
still see the screen. The touch part did not work though. I left it
turned on, charged the battery and what started as small black blobs on
the screen, turned into one huge black blob in the middle of the screen.
I'd say that 2/3 of the screen is now black. All I see is light around
the edges, and it's just light, nothing usable to read or see. It's kind
of like it's self destructing. I even layed it on my dashboard in my car
and let the sun overheat it. I never liked that thing anyhow, so I wont
miss it. I've only messed with it to see what happens to a LCD screen
that was under water. Now I know!!!
 
On the other hand, almost all radios that were flooded do still work. I
just made sure they were well dried before plugging them in. Of course
they all need new speakers, but thats an easy fix.
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