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uniden pc 66 XL no power

Handy Andy said:
Not a lot of people would really understand if anyone whom needed to repair a radio - was simply told - we replace all the caps and that will cost you $$$ amount ON TOP OF the cost to troubleshoot, repair and replace any parts that have failed.

This thread is; if not a good one, an example of cascaded failures - kaos is currently dealing with a lot of small fires as it started out with a voltage problem has now escalated into such an event you describe due to the original problem that caused all of this.

:+> Andy <+:
Click to expand...
Couldn't agree more. In fact, I deeply appreciate you helping out with your experience and especially the detail of your guidance thru these many issues on this thread as well as other threads. Please keep up the great work!

But taking on old radios has certain caveats if one is to keep it for a daily driver, or doing it for the sake of restoration. Which many newbies do.

Radios built in/around the mid 1980s are - lets see now - give or take some thirty five years old? As you well know the mfrs used cheap caps and never intended their builds to last this long.

I'm sure you realize - as I do - that if any want to give these oldies but goodies a new lease on life, that replacing caps is fundamental to that end. We have all witnessed on this thread that the caps had been the culprit.

I had also picked up a 66 some months ago, and it also had various problems. So I started by just replacing the 35 or so caps in it. Lo and behold, most of the issues were solved by doing just that. It also makes it easier to define any other problem that still exists once the caps are no longer the issue. Troubleshooting is never easy for the newbie, so narrowing down the possibilities sure does help some..
 
Yes, you are correct, it just stings the pocketbook when the guy thinks he got a great deal and "it just needs a little work."

Well, I guess that's where we come in...

I myself don't like that "shock and awe" approach either but it is a necessary evil that has to be faced.

Keep up the good work on your end too.

A lot of times, I've fixed radios for free if they've just brought in the right parts.

There is a condition or two; they didn't have the radio butchered somewhere and I'm told to fix it right...rubs me the wrong way and how I've taken to the task of letting others off the hook if they only wanted to protect the investment - not chop at it...

Saves the middleman from themselves...

Regards!
:+> Andy <+:
 
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If you're like me, most of the time I get attached to those little Comedy Boxes - the friendships it made and can still make if treated right - both radio and conversation - makes it hard to let them go.

They may have Hamfests...

We have Coffee Breaks and Truck Stops...

:+> Andy <+:
 
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Well, you have receive, which means the Reactance Modulator is still functional - but no guarantees it's 100 % functional.

If PA works normally - and that's a relative term, the external speaker should have the mic-gain adjustable - meaning that even with this output - there's still a chance that the output wind from the Modulator could be damaged, so audio would be distorted being sent to the Driver and Final - you'd get carrier but backwards swing.

You'd have little recourse except to replace modulator in these instances.

So work thru - but if audio is low, that's why you should try the PA check - at least you'd get volume and a means to verify the Mic amp works - no -preamp in this radio. You can then rule out mic amp.

So the other two then are TR14 AMC Amp/Limiter and TR13 Mic Amp.

Now, you'd better know that you claim to have re-capped it several nights ago. So are any of those caps not installed correctly to the silkscreen? Some in the limiter area, as well as in the AGC/ANL section - are reversed on silkscreen for a reason. So if those failed - re-check your work on those - especially since you are having distorted audio.

Only others are the simpler disc and mylar caps that isolate electrically the stages between TR14 Limiter and TR13 Mic Amp.

Only C90 is directly in the audio line.

You said about rewiring a Cobra mic for this radio - remember there is a bleed down resistor R73 - 4.7K that goes to pin 3 on the Mic jack.

:+> Andy <+:

correction: C95 to C90 - oops...
 
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Another "dumb question session" - what is the Mic element in the mic your' using - it's dynamic right?

Correction Not C95, I meant C90 in audio line - between TR13 and TR14 - should be a 1uF 50V....

I guess I'll need to post some pics under that loom

:+> Andy <+:
 
So did the Cobra 19 Plus, but it had Grey Key - but has an Electret Condenser Element - requires power from the radio - so they brought in bias, a resistor divider network and a filter cap and a gain cell - sent it power thru the audio line - and off she went - Electric Lollypop with a windscreen...to reduce the confusion - they put it on a 5-pin DIN Half-Moon TRS-80 era style - remember I've got a Pin in me before you pull - connector so it couldn't get reworked without the user knowing - beyond a reasonable doubt - they had the wrong mike for that jack.

You mentioned you had to rewire a mic -

Making sure you're testing the radio with a Mic that uses a Dynamic Element - 600 ohm impedance or so.

:+> Andy <+:
 

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