COBRA 2000GTL questions

[Crambone]

Radio is working great other than

1) when radio is off the channel indicator (2 digit) stays softly lit?

2) The Voice Lock when on lets say channel 20 will go from 27.2050 to 27.0270 and 27.0392
wires exist off the voice lock red, orange and yellow, red goes to the bottom of C84 positive side but reading -5.0Vdc, orange goes to an opening next to TP8 14Vdc and yellow goes to the CB PA toggle I believe. All toggles are functioning properly as should.

 

[KneeBiter]

Dim channel selector is usually a symptom of meter bulbs out. If so put in new bulbs and channel selector display with go dark when power is off.

 

[357magnum]

Cram , Just curious , does that radio have the chip in it for upper/lower channels ? As mine on occasion has shown ch 41 freq , while on ch 21 ? It doesn't stay that way , but has done it . As far as dimly lit lights , I can't help you other than suggesting spray Deoxit on that push button switch that changes radio to freq counter on front . Stay Healthy & Safe ! 73 & God Bless ! Leo

 

[Crambone]

Dim channel selector is usually a symptom of meter bulbs out. If so put in new bulbs and channel selector display with go dark when power is off.

Changed both lamps still the same

 

[Crambone]

Cram , Just curious , does that radio have the chip in it for upper/lower channels ? As mine on occasion has shown ch 41 freq , while on ch 21 ? It doesn't stay that way , but has done it . As far as dimly lit lights , I can't help you other than suggesting spray Deoxit on that push button switch that changes radio to freq counter on front . Stay Healthy & Safe ! 73 & God Bless ! Leo

No I don’t get that at all

 

[Crambone]

Just got done recapping entire radio and still same. I am noticing .5 x 1.0 VDc on the selector switch when powered off

 

[KneeBiter]

Did you change the meter lamps with bulbs or led's?

 

[Crambone]

Did you change the meter lamps with bulbs or led's?

Bulbs

 

[KneeBiter]

Bulbs

Strange. I know on the 2000 if the meter bulbs are out the ch display will be lit very dim with power off. Something about the way the power switch is. The bulbs draw just enough with the power off to kill the display. Had several do this and replacing the bulbs always fixed it. Not sure why yours is still lit dim.

 

[nomadradio]

When the routine, simple cheap solution fails to work the next question becomes "how much is it worth to you to fix this quirk?"

We have seen more-exotic fixes to the power switch. Mostly I cop out and solder a 82-ohm 5-Watt resistor across the hot and ground foils on the solder side of the main pc board. This draws about the same "power-off" current that the old meter lamps would do, and allows me to install the LEDs that people want to to see behind their S-meters. LEDs will not draw enough current to hold those digits dark when the power switch is off.

And when there is still that "ghostly glow" from the channel digits the next question becomes "What's it worth to you?"

73

 

[Crambone]

When the routine, simple cheap solution fails to work the next question becomes "how much is it worth to you to fix this quirk?"

We have seen more-exotic fixes to the power switch. Mostly I cop out and solder a 82-ohm 5-Watt resistor across the hot and ground foils on the solder side of the main pc board. This draws about the same "power-off" current that the old meter lamps would do, and allows me to install the LEDs that people want to to see behind their S-meters. LEDs will not draw enough current to hold those digits dark when the power switch is off.

And when there is still that "ghostly glow" from the channel digits the next question becomes "What's it worth to you?"

73

It’s more of annoyance more than anything as the radio is working perfect. So putting in the resistor acts as a bleeder?
So your saying place the resistor from hot to ground.

 

[KneeBiter]

Or try 2 more bulbs in parallel with the meter bulbs. Maybe the lamps you are using do not draw enough to pull the voltage down.

 

[Handy Andy]

I remember having someone taking apart a Cobra 2000, chassis and all, to repair the Frequency Display.

Once repaired, some other strange problems appear, drifting frequency, lights on display staying on - things like that. Found that letting the Frequency counter "Dangle" by it's harness - make it steady and work just fine.

Its' when it got put all back together - the same erratic problems re-appeared.

Well, it came also from a "smoker" that had not had any work done to the radio since they owned it.

The problem is -

The Chassis, once disassembled - your reassembly needs to be "perfectly" clean so the chassis itself doesn't generate a ground loop and noise pickup.

IT will receive just fine, Transmit too, but you'll have weird events like the clock refusing to keep time, the SSB mode - Frequency Counter won't stay steady.

These "support functions" are secondary to the main PCB, which isn't the problem, the board being one SINGLE piece - works just fine, the additional accessories are the errant stuff.

And so are the Accessories at fault, no - just the INTERCONNECTIONS are...

Hey, think of it...a radio or car or anything bolted together - once together - works as a unit because all the parts are equally connected at the same time at the same place with the same levels of corrosion if any or purity of materials for fresh metal to metal connection.

So as a tech, we oftentimes come across radios that don't work 100% right in some way shape or form - it's not perfect. So a lot of times - it's assembly. Even a loose nut on a volume control - the radio bouncing in the truck and one day - its' fine - the day after a trip to New York, it's acting like a piece of carp...noisy receive cutting in and out - talkback too loud one moment - next bump you now have echo on instead...

Ok, so loose parts or parts not making proper contact for SHIELDING can also take a radio from an excellent performer onto the biggest doorstop you have in your home because it just doesn't work like it should.

Why, well, don't ask why, more like how...Do I fix this?

​

I'm not asking you guys to turn this into a "tool time" comedy event - but if you take some time to clean up, straighten - turn controls to check for smoothness or any roughness in operation or even lobbing - bent shaft stuff. You may need to take it in for service but if you have a moment to take it out of the mount and back inside on a table to remove the covers you may be able to repair a quirky problem by simply retightening the case to board screws and check for loose hardware, or wiring that is hanging loose from a broken zip tie.

I've seen Echo boards that came in squealing - all because then they tightened the screw that holds it to the tab, by the Mic audio chip - they forgot to position the board properly - centering it, even using a nylon washer - onto the screw hole and not letting the foil ground of the board, affect the foil to chassis case ground the radio has.

Although nothing big, you can run into some serious audio problems if you position the board incorrectly and the ground of the board, GROUNDS the whole radios' INSULATED FROM EARTH GROUND - thru it's wiring harness - WHAM - problems and noise galore...​

The insulated ground the Cobra 2000s' Main PCB board has, protects it from the elements and the environment it's in, it's why you see those weird voltages - they not weird, you're measuring from spots that are not all connected together like they once were. Ground in one location may not be the same ground in another - so your meter reflects this and in a way - just tattled on the incorrectly reassembled radio.

Just carefully take it apart and reposition - a lot of times - with radios as old as these are. The place it sat "in" for so long, shows up like a bathtub ring, you just re-align to those "points of position" and retighten the screws - a lot of this goes away.

I hope this helps! Because it may just be from being taken apart and put back together with dirty connections are affecting it's behavior. Now, because of age, it needs to be put back together EXACTLY else you'll have some heavy cleaning and burnishing and possibly reflowing of solder to touch up the work to repair this symptom - so you can make the radio work right again.

 

[Crambone]

When the routine, simple cheap solution fails to work the next question becomes "how much is it worth to you to fix this quirk?"

We have seen more-exotic fixes to the power switch. Mostly I cop out and solder a 82-ohm 5-Watt resistor across the hot and ground foils on the solder side of the main pc board. This draws about the same "power-off" current that the old meter lamps would do, and allows me to install the LEDs that people want to to see behind their S-meters. LEDs will not draw enough current to hold those digits dark when the power switch is off.

And when there is still that "ghostly glow" from the channel digits the next question becomes "What's it worth to you?"

73

Ok I did the resistor trick and it solved it!
But now my juices are flowing and I’m curious to some of the other, “what it’s worth to you” fixes? It should be good!

 

[Crambone]

I remember having someone taking apart a Cobra 2000, chassis and all, to repair the Frequency Display.

Once repaired, some other strange problems appear, drifting frequency, lights on display staying on - things like that. Found that letting the Frequency counter "Dangle" by it's harness - make it steady and work just fine.

Its' when it got put all back together - the same erratic problems re-appeared.

Well, it came also from a "smoker" that had not had any work done to the radio since they owned it.

The problem is -

The Chassis, once disassembled - your reassembly needs to be "perfectly" clean so the chassis itself doesn't generate a ground loop and noise pickup.

IT will receive just fine, Transmit too, but you'll have weird events like the clock refusing to keep time, the SSB mode - Frequency Counter won't stay steady.

These "support functions" are secondary to the main PCB, which isn't the problem, the board being one SINGLE piece - works just fine, the additional accessories are the errant stuff.

And so are the Accessories at fault, no - just the INTERCONNECTIONS are...

Hey, think of it...a radio or car or anything bolted together - once together - works as a unit because all the parts are equally connected at the same time at the same place with the same levels of corrosion if any or purity of materials for fresh metal to metal connection.

So as a tech, we oftentimes come across radios that don't work 100% right in some way shape or form - it's not perfect. So a lot of times - it's assembly. Even a loose nut on a volume control - the radio bouncing in the truck and one day - its' fine - the day after a trip to New York, it's acting like a piece of carp...noisy receive cutting in and out - talkback too loud one moment - next bump you now have echo on instead...

Ok, so loose parts or parts not making proper contact for SHIELDING can also take a radio from an excellent performer onto the biggest doorstop you have in your home because it just doesn't work like it should.

Why, well, don't ask why, more like how...Do I fix this?

View attachment 37432​

I'm not asking you guys to turn this into a "tool time" comedy event - but if you take some time to clean up, straighten - turn controls to check for smoothness or any roughness in operation or even lobbing - bent shaft stuff. You may need to take it in for service but if you have a moment to take it out of the mount and back inside on a table to remove the covers you may be able to repair a quirky problem by simply retightening the case to board screws and check for loose hardware, or wiring that is hanging loose from a broken zip tie.

I've seen Echo boards that came in squealing - all because then they tightened the screw that holds it to the tab, by the Mic audio chip - they forgot to position the board properly - centering it, even using a nylon washer - onto the screw hole and not letting the foil ground of the board, affect the foil to chassis case ground the radio has.

Although nothing big, you can run into some serious audio problems if you position the board incorrectly and the ground of the board, GROUNDS the whole radios' INSULATED FROM EARTH GROUND - thru it's wiring harness - WHAM - problems and noise galore...​

The insulated ground the Cobra 2000s' Main PCB board has, protects it from the elements and the environment it's in, it's why you see those weird voltages - they not weird, you're measuring from spots that are not all connected together like they once were. Ground in one location may not be the same ground in another - so your meter reflects this and in a way - just tattled on the incorrectly reassembled radio.

Just carefully take it apart and reposition - a lot of times - with radios as old as these are. The place it sat "in" for so long, shows up like a bathtub ring, you just re-align to those "points of position" and retighten the screws - a lot of this goes away.

I hope this helps! Because it may just be from being taken apart and put back together with dirty connections are affecting it's behavior. Now, because of age, it needs to be put back together EXACTLY else you'll have some heavy cleaning and burnishing and possibly reflowing of solder to touch up the work to repair this symptom - so you can make the radio work right again.

HEIDI ROCKS! Uh UH Uh