HELP My Cobra 146GTL CB doesn't receive AM 8(
Pedro Ribeiro
unplugged and now don't works.
The first symtom was no sound at all, i'v detected C141 in short circuit
near the volume regulator and replaced it, after that the sound appeared and
now i can communicate using SSB (LSB/USB), AM reception is working with
really low sensibility (Only receives near transmissions in line of sight)
Can anyone please give-me help with it (schematics i already have)
i think that the service manuals or someone with high expertise in this
area could easy identify some tipical causes of that problem of low
sensibility in AM reception ... and pointing-me the right direction ...
Thanks in advance.
Pedro Ribeiro (prib...@isel.ipl.pt)
Lou
"Pedro Ribeiro" <prib...@net.ipl.pt> wrote in message
news:9l772c$h3r$1...@venus.telepac.pt...
You may want to ask in rec.radio.cb
>
>
gudule
electrolytics, because its only in Cobra 146GTL I find shorted ones?? I
rarely find shorted lytics in tv or anything else. ???
===================================================
"Lou" <sail...@home.com> wrote in message
news:LcFd7.157994$%a.69...@news1.rdc1.sdca.home.com...
The Packrat®
would change them all out. I have lots of old cobra radios with odd
problems that were solved by replacing the electrolytic caps.
"Pedro Ribeiro" <prib...@net.ipl.pt> wrote in message
news:9l772c$h3r$1...@venus.telepac.pt...
The Packrat®
"gudule" <gudu...@sympatico.ca> wrote in message
news:6qHd7.5186$zg6.6...@news20.bellglobal.com...
DrBoris
> unplugged and now don't works.
> The first symtom was no sound at all, i'v detected C141 in short circuit
> near the volume regulator and replaced it, after that the sound appeared
and
> now i can communicate using SSB (LSB/USB), AM reception is working with
> really low sensibility (Only receives near transmissions in line of sight)
>
it's just that you have little audio on AM. If that is the case it sounds
like the AM detector circuit is not working correctly. In most rigs
this is often just a diode and a few capacitors. The diode could be leaky
so check that, and any associated electrolytic caps.
kc8adu
to change.
this is a uniden and uniden had the same problem with sattelite
recievers.only fix was to replace them ALL!!!
Andre
whole Uniden range or just the Cobras???
Andre
"kc8adu" <nos...@spam.sucks> wrote in message
news:tnicljj...@corp.supernews.com...
gudule
had to change all the lytics on the video board , about 35 of them.
The other thing to think about for the lytics in CB radios is that it is
powered by l2 volts DC.
Do u know of a single CBer that can plug the 2 DC power(black and red)
wires to the proper polarity without mixing them up ???? How come they
dont know that the black is minus, and the red is plus???? Are they color
blind. ? Or just blind ??? Or ???
But I love it , I have, for 25 years , been making tons of money repairing
CB radios plugged reversed.
So plugging lytics on reverse voltage may be another reason they end up
shorting more often in CB radios.
=================================================
"kc8adu" <nos...@spam.sucks> wrote in message
news:tnicljj...@corp.supernews.com...
Boldor
wires to the proper polarity without mixing them up ???? "
Yes, I know many. Most are qualified technicians using CB as a playground to
test Antenna theories.
"gudule" <gudu...@sympatico.ca> wrote in message
news:Rbke7.28624$zg6.2...@news20.bellglobal.com...
Andre
A club that i once belonged to used to install a bridge rectifier inline on
all its "Loan" sets to stop this from happening....
73's Andre
Richard McCollum
"Boldor" <boldo...@optusnet.com.au> wrote in message
news:3b79d50c$0$20905$7f31...@news01.syd.optusnet.com.au...
> "Do u know of a single CBer that can plug the 2 DC power(black and red)
> wires to the proper polarity without mixing them up ???? "
>
>
> Yes, I know many. Most are qualified technicians using CB as a playground
to
> test Antenna theories.
>
Given the geography and regulatory situation in Oz you may well be correct.
Given that you can fiddle on the 50-54 band in the U.S. by answering 27 of
35 questions at a cost of $10 bucks CB is a waste of metal. Add a 5wpm code
test and you can have all the fun at 28.3-28.5 you can stand.
Part of the problem mentioned above is that with US wire coding, black is
ground unless in the presence of white in which case black is hot and white
is ground except in the presence of green in which case green is ground,
white is neutral, and black or red is hot. If all the poor doof ever did
was replace an outlet, he may well get it wrong.
Dick NØBK
The Packrat®
"gudule" <gudu...@sympatico.ca> wrote in message
news:Rbke7.28624$zg6.2...@news20.bellglobal.com...
gudule
"The Packrat
> Or plugging them into house current.
I presently have for repair a Radio Shack CB base station TRC-433 that has
most "CERAMIC" caps exploded, beside lots of diodes and transistor blown or
shorted. It is pretty sure it was plugged into house current like u said. I
have never seen , in my 40years of troubleshooting experience ,exploded 50
volts ceramic caps.
And yesterday night, I forgot to mention that about an hour before my post
, a customer brought a Cobra 19 Plus with a 30A fuse in the inline fuse
holder, instead of the standard 2A fuse. He said he bought it "as is" in a
garage sale. The protection diode is open, it put out 1.5 watt, modulation
is a bit distorted, and just a faint speaker noise in receive.I will check
it , but its probably good for parts.
Most plug the radio reversed because they just get mad and impatient , and
it is "mind over matter"." I want it, I want it now, I want rite fucking
now." Its instant gratification or ELSE. Their pride is at stake especially
when their friends are around. The problem = The P.A. switch was in the
wrong position???
I love those guys. They have to see smoke or something spark. They are like
the "Terminator" , they just never give up, trying to destroy their radios.
=================================================
Mr R@t / Alex - J10 [2.33za]
> Part of the problem mentioned above is that with US wire coding, black is
> ground unless in the presence of white in which case black is hot and
white
> is ground except in the presence of green in which case green is ground,
> white is neutral, and black or red is hot. If all the poor doof ever did
> was replace an outlet, he may well get it wrong.
>
> Dick NØBK
>
indeed [I used to work for a UK company with US owners which made kit for
the TV industry, I was one of the few people who knew the US wiring code -
every time we had to make up leads for the big NAB exhibition I had to
explain this to my colleagues!]
But here in England its a bit easier. For house wiring black is neutral, red
is live [hot] and earth [ground] is green, yellow and green or bare copper -
so the amateur electrician is *far* less likely to blow his radio up [unless
he *does* plug it in to mains, which would result in an even more
spectacular electronic barbecue as we are a 230V country!]
incidentally most second hand CB sets I obtain [unless some fool has been at
them with a screwdriver trying to get more power or extra frequencies] seem
to be in good working order...
Alex
--
Alex / Mr R@t - Junk-Chun 10 Sound System, Reading
attention: headers are munged to avoid spam
correct e:mail is : <golf><romeo><tango>23<AT>ratcotel<DOT>net
network23 reading: http://www.ratsnest23.org
Richard McCollum
"Mr R@t / Alex - J10 [2.33za]" <gr...@spam-nyet.sssr.su> wrote in message
news:QsNe7.37595$zs.3...@news11-gui.server.ntli.net...
And with the ring mains, you have the capacity to produce one hell of a
spectacular display.
Mr R@t / Alex - J10 [2.33za]
"Richard McCollum" <rmcco...@worldnet.att.net> wrote in message
news:cMNe7.47676$gj1.4...@bgtnsc05-news.ops.worldnet.att.net...
> And with the ring mains, you have the capacity to produce one hell of a
> spectacular display.
>
only if some idiot has replaced the plug top fuse with a nail or similar
unsuitable piece of metal. [All UK plugs are fused, apart from specialist
ones these days only used for lighting circuits or stage lighting.]
Although the UK's mains wiring system may seem strange to outsiders, it is
*very* safe unless you are *extremely* silly [in which case you are going to
light the damn building on fire no matter what] and is actually the most
popular electrical wiring system in the world, many Asian and Eastern
countries having adopted it.
However I do have an even better story to tell. I now work in the
entertainments field, setting up sound systems for discos and raves etc.
Now the colour code for *flexible cable* in the UK and Europe is brown=live,
blue=neutral green/yellow=ground. As you all know there are three phase
supplies in large buildings. In the UK the colour scheme for internal wiring
is red, blue, yellow = phase wires, black = neutral, green = earth. UK three
phase is 230/*400* volts
A few years back, a rather dubious crew in London were setting up in a
warehouse. Their "electricians" had previously been drinking, and no doubt
taking all kinds of drugs. Anyway, this addled their brains to such an
extent they mangled their colour codes whilst wiring in a distribution panel
directly into a three-phase board, having forgotten an important red CEEform
plug [this is a kind of connector used for three-phase connection in Europe,
not sure if you use it in the USA].
Some fool thought = aha! red= live, *BLUE* = neutral [remember what I said
about three phases :) ]
of course there is now 400 volts where there should only be 230V - BANG! The
distribution board *melts* and most of the
sound equipment belonging to these fools in rendered unserviceable. Luckily
no one was injured/killed - but that sound crew is no longer in business,
probably just as well for the safety of the kids at these events.
A good reason if any not to mix business with pleasure - [or wiring colour
codes].
stay safe everyone...
DrBoris
>
> "Richard McCollum" <rmcco...@worldnet.att.net> wrote in message
> news:cMNe7.47676$gj1.4...@bgtnsc05-news.ops.worldnet.att.net...
>
> > And with the ring mains, you have the capacity to produce one hell of a
> > spectacular display.
> >
> only if some idiot has replaced the plug top fuse with a nail or similar
> unsuitable piece of metal. [All UK plugs are fused, apart from specialist
> ones these days only used for lighting circuits or stage lighting.]
>
to his brother, who proceeded to plug the red and black DC wires directly
into 240 mains AC! Needless to say, the rig ceased to function. It was
handed
to me for repair. Heaps of transistors had been fried together with the
audio
chip and voltage regulator, and of course the idiot diode! However,
not a single cap had blown!
Bill Nelson
: Part of the problem mentioned above is that with US wire coding, black is
: ground unless in the presence of white in which case black is hot and white
: is ground except in the presence of green in which case green is ground,
Not quite. Black is hot and white is common. There is no ground, as such.
: white is neutral, and black or red is hot. If all the poor doof ever did
: was replace an outlet, he may well get it wrong.
Green is the equipment ground, it is not a current carrying conductor.
--
Bill Nelson (bi...@peak.org)
Pedro Ribeiro
eletrolitic caps, for the ones interested to know details, it was C17 (near
IC TA75902P) that seems to feedback de AGC of AM reception.
Thanks to everyone that contributed with sugestions via News/Email !
(Special thanks to Hardy Andy that pointed-me the problem area).
----------------------------------------------------------------------------
-------------------
Has anyone tried the modification sugested in the bottom of the page
http://members.tripod.com/~Malzev/cb-funk/tr-296.htm
with the title "Improved receive gain" ?
It worked ??
Some of this days i'll try it!
Best Regards
Pedro Ribeiro (prib...@isel.ipl.pt)
"Pedro Ribeiro" <prib...@net.ipl.pt> wrote in message
news:9l772c$h3r$1...@venus.telepac.pt...
satob
australia
Boldor <boldo...@optusnet.com.au> wrote in message
news:3b79d50c$0$20905$7f31...@news01.syd.optusnet.com.au...
satob
receiver overhere in australia they are well liked for a satellite receiver
on cband or ku band, we prefer the humax5400 actually the irdeto one with
the embedded cam, plus another slot for seca or whatever another good one
is a humax 800ci , i also disagree with the theort you have about iniden
cbs alot come out of the factory out of tune it isnt funny they need tuning
anyway especeally pc122 they tend to be death as well as drift alot on ssb
it doesnt sound like a reverse polarity to me it sounds like the agc control
is crook or a few caps as well as even a can could be done, anyway thats
my opinion on this subject, cheers 73s 88s , david nsw australia.
Boldor <boldo...@optusnet.com.au> wrote in message
news:3b79d50c$0$20905$7f31...@news01.syd.optusnet.com.au...
Dave Stanton
> only if some idiot has replaced the plug top fuse with a nail or similar
> unsuitable piece of metal. [All UK plugs are fused, apart from specialist
> ones these days only used for lighting circuits or stage lighting.]
Not quite correct, CEE 110V on building sites etc are not fused. You mean all UK domestic plugs
are fused and don't forget there are some old radial circuits in existance which are fused at the
consumer unit( fuseboard) and use the old style 15A round pin plugs which don't contain fuses.
Cheers
DAve