Strange McKinley issue

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superstar
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Strange McKinley issue

Post by superstar » 30 Oct 2013, 07:20

Here's an odd one for ya, I picked up a cheap but half tidy McKinley yesterday, it all works as it should tx/rx, but it also receives a broadcast station similar to talk sport :lol: in the background regardless of what channel you're on, it registers no signal and can be heard even with the volume down and the squelch up ( volume and squelch works normal for cb operation ). I've never come across this before, it look tidy inside too, what do you thinks up with it? :?
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Re: Strange McKinley issue

Post by wa10 » 30 Oct 2013, 08:10

is it epromed?, i have had similar issue with a few eprom boards , one was in a McKiney, fingering the 5v reg on the eprom board stopped the music, changing the reg fixed it.

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Re: Strange McKinley issue

Post by Mudslinger » 30 Oct 2013, 08:22

My Mckinley also did the same thing...

I found that running a wire from the Microphone socket to the metal part of my microphone sorted it.

Maybe a poor earth in the radio somewhere?
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Re: Strange McKinley issue

Post by superstar » 30 Oct 2013, 10:03

Hi, there's no eprom in there, all standard, I tried the mic wire thing but made no difference, the louder I have the volume up the more it drowns out the broadcast station, it's receiving 5 live :shock: , it a nice rig I'd love to fix this annoying fault, I've just turned down the volume to listen to the news :lol:
She's half tidy here's a pic :)
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Buying and hoarding CB radio's is an illness
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1980-1993, "AL Capone"
1993-present, "Superstar"
occupation-running a retirement home for elderly cb radios
Fozzy Bear dont care ya know, so er thats the story!

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Re: Strange McKinley issue

Post by bigpimp347 » 30 Oct 2013, 10:17

you can do it on just about any radio :)
if you place your finger near the VCO area you will be able to receive AM broadcast ;)

and yes i can prove it before the know it all's start saying you can't, i have two videos, one on a Uniden 100 other is a Pama Danita mk5..

check around the VCO area for a bit of stray solder, damp, or some other short,
clean the board if needed, and check component side also, you might have a shorting out cap which is doing this..
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Re: Strange McKinley issue

Post by superstar » 30 Oct 2013, 12:40

Here's the solder side, I can't see anything but there again I ain't got a clue what I'm looking for :?
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Buying and hoarding CB radio's is an illness
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1980-1993, "AL Capone"
1993-present, "Superstar"
occupation-running a retirement home for elderly cb radios
Fozzy Bear dont care ya know, so er thats the story!

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Re: Strange McKinley issue

Post by bigpimp347 » 30 Oct 2013, 13:51

check around the metal plate area, possibly remove it and see if the noise goes.
just check all the solder around there, make sure none has been changed/new and similar area component side too.
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Re: Strange McKinley issue

Post by superstar » 30 Oct 2013, 14:03

bigpimp347 wrote:check around the metal plate area, possibly remove it and see if the noise goes.
just check all the solder around there, make sure none has been changed/new and similar area component side too.
If I remove that plate my $h1t soldering iron will never allow me to put it back on neatly, what's that plate for anyway ?
Buying and hoarding CB radio's is an illness
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1980-1993, "AL Capone"
1993-present, "Superstar"
occupation-running a retirement home for elderly cb radios
Fozzy Bear dont care ya know, so er thats the story!

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Re: Strange McKinley issue

Post by Buick Mackane » 30 Oct 2013, 15:18

superstar wrote: what's that plate for anyway ?
An RF shield

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Re: Strange McKinley issue

Post by bigpimp347 » 30 Oct 2013, 16:23

yup usually an RF shield, but seeing as the radio has a lid another 4mm away and the RF is floating all around the radio i've never seen what they can do.. :)
you could have a bit of crap beneath it or even a dodgy joint,

are there any areas on the board you can touch where the heterodyned signal goes ??
you might even have a board to chassis cap gone bad
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Re: Strange McKinley issue

Post by Clint » 30 Oct 2013, 21:22

bigpimp347 wrote:yup usually an RF shield, but seeing as the radio has a lid another 4mm away and the RF is floating all around the radio i've never seen what they can do.. :)
Its not the same, the lids are tied to the chassis and not to the ground rail, the chassis and ground should be capacitively decoupled from each other..
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Re: Strange McKinley issue

Post by Clint » 30 Oct 2013, 21:24

bigpimp347 wrote:cap which is doing this..
My first guess - or a harmonic being produced from one of the oscillators vco or xtal.
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Re: Strange McKinley issue

Post by superstar » 31 Oct 2013, 10:18

Here's a vid of it in action :?
http://youtu.be/oeIUL3VmtnQ
Buying and hoarding CB radio's is an illness
Cb handle
1980-1993, "AL Capone"
1993-present, "Superstar"
occupation-running a retirement home for elderly cb radios
Fozzy Bear dont care ya know, so er thats the story!

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Re: Strange McKinley issue

Post by NUBSTER » 31 Oct 2013, 12:18

This might sound a silly question as I am not up on technical stuff inside of a radio, but dose it do this if you took the radio say mobile or to another place (QTH), just wondering if its actully somthing within your home thats causing it

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Re: Strange McKinley issue

Post by Buick Mackane » 31 Oct 2013, 12:34

Im not at all familiar with this radio. But looking at your pic of the solder side of the radio i dont see any caps between the chassis & ground :roll:

I wonder if the problem could be the audio amp itself

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