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Troubleshooting 101

2FB327

2FB327

Active Member
Oct 31, 2012
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Has anyone ever posted a "how to" on troubleshooting say from the final back?
I do remember one a few years back that was helpful on no power-no receive.
But I am looking for a step by step on how to test/repair a 29 with no receive, using a scope/signal generator.
 

I have found the Cobra service manual be helpful. Eventhough it is not a step by step tutorial, you may want to perform a receive alignment based on the service manual and you may end up repairing it if a pot or can is not aligned properly or has been detuned by someone. Good thing is that you have a signal generator and a scope.....Good luck.
 
thanks

I have compiled a bunch of info from cd's,books,cbtricks, i'm looking on how to put it together.
 
it would be pretty laborious to try to do a "one size fits all" type of troubleshooting guide.

it really needs to be for a specific problem to be effective.

sure, there are common techniques like signal tracing and signal injecting, but how to apply them in particular situations is what troubleshooting is all about.

i would suggest getting a copy of "understanding and repairing CB radios" by lou franklin.

he will take you through the whole process and then some.

it may take a few readings to get some of the material, but if you keep at it; the lightbulbs will come on.
LC
 
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Thanks, that's one of the books I have been reading and re reading.
I'm learning to understand the black box diagrams and trying to compare that to the voltage charts I found.
What I should have asked is where you would start say with a Cobra 29, It receives and you can hear the bench radio thru it.
Has a carrier, and the led tx/rx light goes from green to red, but no modulation thru the bench radio or on the scope.
So what I am looking for is what test point to start at and which way to go, to start at the final and work back or the chip and out and how to do that.
Thanks.
 
loosecannon said:
i would suggest getting a copy of "understanding and repairing CB radios" by lou franklin.
he will take you through the whole process and then some.
it may take a few readings to get some of the material, but if you keep at it; the lightbulbs will come on.
LC
Click to expand...

I couldn't have said it better. The "secret" (if there is any) to repairing CB radios or any electronics, is being able to read a schematic and understand how each of the various circuits function as well as the purpose of each component in a given circuit. This isn't something that's learned overnight.
The book that LooseCannon suggested is the BIBLE on cb radios. This is a "must-have" for any cb tech. 73s.

- 399
 
I have thought of doing some YouTube videos on this very subject. Not that I am a master guru of this stuff but I can see where it would help the :want to learn" folks. The next issue is who would be interested. That is one of the big show stoppers. Takes a lot of time and effort to put something like this together only for a handfull of folks to watch.
 
I remember seeing that go kart link somewhere, I think it was the post on that "How to" I was talking about.
I'm learning as I go and now got the tools to start. After reading Lou Franklin's book I'm starting to get it, but as in the case above there has to be a starting point with the DVM or Freq counter.
Getting the receive back is more than half the battle, what I need help in is getting to identify the parts in the transmit circuit and compare that to the chart and voltage points.
Perhaps your right and there are only a few left in repair, I guess it easier to throw it away and buy a new one than to fix it. And even if you try to repair or learn to repair something that is broke you get chastised with comment like "take it to a professional".
I was involved in photography for over 40 years and in the beginning it was all about not sharing, but as digital came around many started to share in there success, maybe I'll find someone with the time to share.
 

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