Problem with my CB

Send it to Doug at customcbradios.com ... i am sure he will fix it,,, if not can hook you up with a sweet rig to replace it...

 

here is a very similar post
http://www.thetruckersreport.com/tr...dio-forum/177709-i-think-i-burned-my-new.html

 

If it where me, i would first confirm that the protection diode is blown and if so try jumping it to see if you get power... Before i would do anything however i would make sure you have the proper rated fuse inline!

if after jumping the diode there still is no power then it would be safe to say you can smack yourself all the way to the CB shop for a new radio

 

One can only assume you have never studied the schematic to a typical CB. The diode is in parallel with the supply input. So called 'jumping it' can only produce a dead short circuit to the power feed. First you test the diode. If the diode is shorted you replace it, knowing the radio had been protected and the fuse was not too high in rating. If it is open you replace both it and at minimum the audio output capacitor, typically 470 uF/16v. Higher voltage ratings are good as long as it will fit. Filter caps may also have been depolarized which will result in leakage induced heating until they burst, so You may wish to test these caps for ratings and leakage. Then you re-power the radio to see what other failures if any have occurred. I most strongly advise people who do not know electronics and do not know how to repair radios to not give advise on the subject. Those uninformed may assume you know what you are talking about and following bad advise cause themselves even more financial harm.

I remember in 81 working in an R&D lab hearing a co worker advise a third worker it was safe to put an electrolytic 100 uF/400vdc capacitor across the 117 volt AC power line. No I cannot explain how this person got his job. I lectured them both on the explosion danger and set up a demo in a box with a protective window, fused said demo at 15A to provide line protection. The noise brought people down from the floor above to see what had happened. They never questioned me again. Another bonus was the third worker never trusted advise from the co worker again.

 

Speaking of assumptions, any one else think that OP is shorting out when connecting radio to power ?

Just a thought, i'll try not to have more of 'em

 

I'm by no means a cb or electronics expert, but is it possible you simply have the wires hooked up backwards? Cb + to veh - and vice versa. I've seen simple problems cause people a lot of headaches.

 

I think you are 100% right about that op diode.Thats what happens when you hook it up the wrong way. But I have a radio that does the same thing and I am determined to get that sum b working if I have to smash it into a thousand pieces. It could also be a final or the more dreaded I.C.

 

As a 40-year commercial tech (and considerably longer in CB and amateur radio), I echo the opinions of Dr. No and the others who suggest that the protection diode originally did its job. The idea is that it's a low current (think "amperage") rated diode that, when the power is connected correctly, is kinda "ignored" by the DC going into the radio (it's placed right across the power leads inside the chassis, with the anode connected to ground and the cathode (the banded end) connected to the hot/positive/red lead. Putting power to the radio with the leads reversed allows current to flow from the black lead through the diode to the red lead, and the diode shorts. With a proper sized fuse, said fuse will blow. If you try to get around this protection by putting in a huge fuse (like 20 or 30 amps), the teensy protection diode will burn "open", meaning it no longer provides a path for the current, and the power supply current can now find its merry way through the radio, commonly destroying the power transistors (they're like two diodes in one package), the audio chip, most (or all) of the electrolytic capacitors that filter the DC lines inside the radio, the internal voltage regulators (variously giving 5, 8, 9, or 10 volts to components that run on those lower voltages, and those components depending upon those lower regulated voltages.
If you had the good fortune to *not* have turned the radio to the "on position" with the huge fuse inline, you may have to replace only the protection diode, a couple of electrolytic capacitors between the power connector and the power switch, and possibly solder wire in a few places to replace the printed circuit traces that *used* to carry power to the switch -- and the final transistors, as they are sometimes fed more-or-less raw current from the DC input.
At best, you'll only have to have a handful of components replaced, but those may well cost $30 hanging on the wall. If the radio got turned on, the parts cost alone might well exceed the price of a new radio. And with a new radio, you'll not have to worry about how many parts were stressed to the point of almost failing, and you might well see them fail as you're bouncing merrily down the road with your newly-rebuilt radio.
Rule of thumb: if the stock rated fuse (2.5 or 3 amps) blows when you hook up power correctly, disconnect the power and do a little troubleshooting. If you're lucky, it was just that little 1n914 or 1n4001 diode that shorted out to do its job, and replacing it will get you back on the air relatively inexpensively.
Sorry my explanations are so long.....I've been told that when someone asks me what time it is, I tell them how to build a clock.......
Toodles and good luck,
-- Handlebar --
diddly dahdidah

 

Well said and I agree with you 100%.Now I have been fortunate enough to to have tested a few of these diodes to see if they work properly and I'll be ,they do.So I shut my radio off until I could get the diode replaced and it worked fine after I figured out what I did.As long as you shut the radio off after it happens you should be ok as I was but if you try to continually get some power by hot wiring it ,well kiss that radio good by.