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Cobra 142 over volted on DC power and smoked :(

Well gents after finally finding d407 on the back of the tiny board stand off near the smoking coils , it was fine ! So another lengthy search began for d60 and once I tracked it down she was popped !! I stole a diode from a dead President John Q. (of similar size and color) couldn't find exact match she fired right up !!! Thanks so much you guys are the best ! Please check out my other thread I could use some help with my Varmint 450 XL Tuber ! The keying relay is shot :( more details in the post but I cant thank you all enough!! Ill align it tomorrow and see if anything else is out of whack and update !!

Knees in the breeze and 73's from Winkdogg 4-2-0 in the Garden State!!
 
Oh and is it me (I haven't read schematics in quite a while) but cobra makes schamits extremely hard to use for points of reference unless I forgot reading schematics 101 which is 100% possible but I pulled out my Connex 3300hp schematic and I had no problems finding anything on there … Oh well this old radio is talkin and my pop would be proud ! Thanks again
 
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Congratulations! You stuck with it and got it working.

The date on the tech note in the link I posted explains it all. The factory schematic is correct for the first-year production. All of them produced after late 1978 have the zener in that spot. But the schematic was never updated to reflect this early production change.

73
 
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I am not personally familiar with the inside of that radio, but it should be at/near the DC input. Maybe even right across the pins.

Edit:

Looking back at your original post - check across the smoking coils - that’s exactly where it should be.

Bingo !! It was between the DC inputs on the back of a little 1"X1/2" standoff board . Now D60 was a whole different deal lol hard to find but replaced and firing right up !
 
Congratulations! You stuck with it and got it working.

The date on the tech note in the link I posted explains it all. The factory schematic is correct for the first-year production. All of them produced after late 1978 have the zener in that spot. But the schematic was never updated to reflect this early production change.

73


Great Point nomad I overlooked that (and the diodes several times lol) but thanks for the kick in the coax I needed to all of you ! Gentlemen as well as Scholars 73's
 
Hey
Oh, yeah. Always FUN to work on a radio that has been even been indirectly struck. Changing parts for days. Even after it gets fixed - too . . .


That was my biggest fear !! I hit my Connex 3300hp with 21.65 Volts it took me a month and 6 multimeters to get her screaming again !! luckily Cobra knew I was an Idiot when they designed the 142 Board lol !! Why does my 12-15 volt 25amp power supply swing up to 22 volts bc its got a dirty know ??? I replaced all the regulators and the potentiometer for variable voltage , its very stable for a "VICTORY 25" but still spikes over 20 volts …. Stuff happens its been great for the $75 I Paid !!!! MY $400 Astron is much nicer lol
 

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