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Cobra 2000 gtl issue

Whew!

Keep going - see where or why TR41 and TR42 are not getting voltage...

Once they get voltage ... then...

Tr41 and Tr42 - were they checked? I think you said TR41 showed NPN - but what about TR42?
 
Then you have to find out why the 12V is not getting there - or from there - to the MODE Switch...

Thinking blown trace...You solved VR10 - so you should get plenty of carrier - you're not...so open line, trace or lead?

(or bad spot on the switch)
 
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We're staying tuned...
giphy.gif
 
But does it make it to the Driver and Final?

AM mode is 8V but the output of the AM Regulator section - when open, is about 12V (Battery Supply no load) when you apply load, that drops to about 5 to 6VDC - audio supplants within it. You adjust VR10 for this voltage which shows up as carrier on the RF meter. If everything else works right.

Check the other poles of the Mode switch - the one from AM Regulator - to Mode SW to put AM on the TP7/TP8 line - you have 4 to 5 poles on that rotary - choose wisely.
 
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Ok, did you see if your were getting power to the AM Regulator TR41 and TR42?

Then there is a wire that lifts from the board, from that area that head back up front to S403 - your MODE switch.

IT has several "poles" on it, two for 8 volts - and at LEAST one for 12V when in SSB mode and one terminal is saved for this wire that goes to the SSB/AM Power Output section of that switch. - the one that shows continuity to TP7/TP8 - that should be the section that this wire and the switch connects the output of the AM Regulator to this TP7/TP8 wire bundle.

You have to check that contact and make sure it shorts that terminal to the switch's TP7 / TP8
 
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I am sure that this is not particularly helpful..... but I am confused.
The original post #1 said you had output on SSB but not AM.

These recent entries seem to indicate that Vcc is not making it to the driver/final at all.

How can you have SSB output with no DC volts to the driver/final?

Am I missing something?
 
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