The simplest test is to just jump out the switch. Less is more. Easy stuff first.
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Cobra GTL 2000 Power up Issue
- Thread starter AJAY0618
- Start date
you won't find any voltage on that switch.
it switches the ground side.
your readings look fine if i understand them correctly.
please try the test on the AC/DC switch on the back of the radio from my previous post.
LC
it switches the ground side.
your readings look fine if i understand them correctly.
please try the test on the AC/DC switch on the back of the radio from my previous post.
LC
LC,
You are definitely on to something with this switch. Rather than solder it I user alligator clips on the front terminals. Well, what happened will tell the tale.
1. CB band is perfectly illuminated
2. AM does not illuminate but LSB and USB do when I switch to them.
3. The counter is on but moving through numbers randomly.
4. The meters are not illuminated and could be bad lamps.
5. I can switch between counter and clock and I can observe and extra barely flashing digit after the minute digit.
6. The clock does not seem to be counting time.
I may need to change caps on the counter as well but before that this switch looks like it needs a change.
Arthur
I believe you said you noticed faint display lit with power off. I'm too lazy to go back and read. That is a symptom of blown meter lamps in this particular radio. New lamps cures that.
No LED's. I know some people like them. They are a headache. Just get new grain of wheat 12v lamps. You can get a bag of them on ebay cheap. https://www.ebay.com/itm/3945982374...d=link&campid=5336136228&toolid=20001&mkevt=1
Okay so here is an update!
Replaced bulbs that were out on everything except those that are below the CB Channel indicator which now does not illuminate at all when the unit is off and nicely when it is on. This confirms a user's post about this issue.
Replace the switch with one I got from Ebay for $8 and eureka the unit comes on with everything illuminated except those below the CB indicator.
The counter is still moving randomly but that may be due to not having the antenna connect to the unit.
Also, the clock illuminates with one digit after 12:00 but it doesn't seem to be working.
Replaced bulbs that were out on everything except those that are below the CB Channel indicator which now does not illuminate at all when the unit is off and nicely when it is on. This confirms a user's post about this issue.
Replace the switch with one I got from Ebay for $8 and eureka the unit comes on with everything illuminated except those below the CB indicator.
The counter is still moving randomly but that may be due to not having the antenna connect to the unit.
Also, the clock illuminates with one digit after 12:00 but it doesn't seem to be working.
This is a pretty classic behavior caused by failing electrolytic capacitors in the clock/counter module. Most of the 10 or 11 of them in the shielded box serve to keep separate circuits from feeding false triggers into one another. The "twitchy" behavior is pretty classic.
Only cure is to replace the entire set of those caps inside that module.
Oh, and that counter display is NOT connected to the antenna in any way. It taps into the radio's internal circuits and will read your frequency no matter what is connected to the antenna socket.
But only when it's working.
73
i'll just add to Nomad's post to say that the PC board in the counter module is a double sided plated through board.
that means that the solder connection on the bottom of the board is also connected to a trace on the top of the board and they are connected with a tiny copper tube that goes through the hole.
if you do not have the right equipment/experience, you can EASILY pull this copper tube out thereby disconnecting the two traces.
a good quality desoldering iron is the way to do it.
LC
that means that the solder connection on the bottom of the board is also connected to a trace on the top of the board and they are connected with a tiny copper tube that goes through the hole.
if you do not have the right equipment/experience, you can EASILY pull this copper tube out thereby disconnecting the two traces.
a good quality desoldering iron is the way to do it.
LC
Listen to the man he knows whereof he speaks.
The only tool I ever found to do this job with a minimum of damage to the foil traces and plate-through sleeves inside the holes is a desoldering iron with a hollow tip and a vacuum pump.
Years ago RatShack sold one with a rubber bulb to do the sucking. We got by with that tool for a couple of decades.
Seems to me I posted a picture guide to the spots on this board were we routinely see a foil pad separate from the board. Taking the excess lead length sticking out of the board's solder side and laying it over onto the adjacent pad on the same circuit is what I call the "combover" fix.
I'll see if I can dig it up, or post a new one if I can't.
73
The only tool I ever found to do this job with a minimum of damage to the foil traces and plate-through sleeves inside the holes is a desoldering iron with a hollow tip and a vacuum pump.
Years ago RatShack sold one with a rubber bulb to do the sucking. We got by with that tool for a couple of decades.
Seems to me I posted a picture guide to the spots on this board were we routinely see a foil pad separate from the board. Taking the excess lead length sticking out of the board's solder side and laying it over onto the adjacent pad on the same circuit is what I call the "combover" fix.
I'll see if I can dig it up, or post a new one if I can't.
73
It just takes a little care in how you do it. Lay the desoldering braid down, iron on top to heat. Don't use a lot of pressure and don't move around side to side. Heat can weaken the grip of the pad and the solder braid will "grip" on to the pad.... so any lateral movement can have a tendency to rip the pad off of the board.
Even the manual pump style vacuum desoldering tools(Soldapullit?) can do damage. What is nice about the elctronic type is that there is very little shock/vibration. You just place the tip, melt the solder, push the trigger and the solder is gone.
There is an option (hack?) to enable a “seconds” counter to the clock. I believe it involves removing a diode. It is my understanding this is shown in the factory schematic though I do not have that schematic to be certain.
This might be the cause of your flashing digit to the right of your “minute” digit on the clock.
73
David
This might be the cause of your flashing digit to the right of your “minute” digit on the clock.
73
David