Uniden Grant (PC-409ac)

[DX-300]

Looking for some advise regarding a repair . Uniden Grant no receive audio needle not showing signal . no transmit, needle moves slightly tx/rx led flickers green red during tx. PA has audio output

 

[doffo]

Looking around, I found a thread here in the forum:
Old uniden Grant PC409ac board


That may be what you are experiencing. It isn't a guarantee that it is that specific capacitor, but in this day and age, it may be the time to recap. Otherwise, look for any cold solder joints underneath the board. I found one hidden from the eye using a plastic tool gently pushing underneath the board, and that old TRC-449 sprung to life.

Hope you can get that ol Grant up and going.

And now that I looked at the picture... Isn't that the same board used in the Cobra 140/142 GTL radios?? Reason I ask is because there is a service bulletin for those radios where the voltage regulator gives up. That might not be the case, but the board looks pretty close to it.

---- After some more looking, our very own Robb had the same radio that was giving him trouble. He got it squared away in his posts.
Uniden President Grant Short?

Should be a good start for ya. Let us know how it goes.

 

[nomadradio]

What tools do you have to investigate further? A second radio is a big help to eavesdrop on the radio under test. Eyeball the radio for oxidation. If it was stored someplace excessively humid, you might want to skip it. That kind of radio tends to have multiple faults. Doesn't mean it can't be fixed, but it raises the challenge level in a big way.

73

 

[doffo]

What tools do you have to investigate further? A second radio is a big help to eavesdrop on the radio under test. Eyeball the radio for oxidation. If it was stored someplace excessively humid, you might want to skip it. That kind of radio tends to have multiple faults. Doesn't mean it can't be fixed, but it raises the challenge level in a big way.

73

The smell that is given off by the old Cybernet boards.... Very musty lol.

 

[DX-300]

Looking around, I found a thread here in the forum:
Old uniden Grant PC409ac board


That may be what you are experiencing. It isn't a guarantee that it is that specific capacitor, but in this day and age, it may be the time to recap. Otherwise, look for any cold solder joints underneath the board. I found one hidden from the eye using a plastic tool gently pushing underneath the board, and that old TRC-449 sprung to life.

Hope you can get that ol Grant up and going.

And now that I looked at the picture... Isn't that the same board used in the Cobra 140/142 GTL radios?? Reason I ask is because there is a service bulletin for those radios where the voltage regulator gives up. That might not be the case, but the board looks pretty close to it.

---- After some more looking, our very own Robb had the same radio that was giving him trouble. He got it squared away in his posts.
Uniden President Grant Short?

Should be a good start for ya. Let us know how it goes.

Thanks I have looked for cold solder joints with a palastic tool and freeze spray, is there a diagram that gives values on components that i can test for?

 

[DX-300]

Looking around, I found a thread here in the forum:
Old uniden Grant PC409ac board


That may be what you are experiencing. It isn't a guarantee that it is that specific capacitor, but in this day and age, it may be the time to recap. Otherwise, look for any cold solder joints underneath the board. I found one hidden from the eye using a plastic tool gently pushing underneath the board, and that old TRC-449 sprung to life.

Hope you can get that ol Grant up and going.

And now that I looked at the picture... Isn't that the same board used in the Cobra 140/142 GTL radios?? Reason I ask is because there is a service bulletin for those radios where the voltage regulator gives up. That might not be the case, but the board looks pretty close to it.

---- After some more looking, our very own Robb had the same radio that was giving him trouble. He got it squared away in his posts.
Uniden President Grant Short?

Should be a good start for ya. Let us know how it goes.

Thanks I have looked for cold solder joints with a palastic tool and freeze spray, is there a diagram that gives values on components

What tools do you have to investigate further? A second radio is a big help to eavesdrop on the radio under test. Eyeball the radio for oxidation. If it was stored someplace excessively humid, you might want to skip it. That kind of radio tends to have multiple faults. Doesn't mean it can't be fixed, but it raises the challenge level in a big way.

73

What tools do you have to investigate further? A second radio is a big help to eavesdrop on the radio under test. Eyeball the radio for oxidation. If it was stored someplace excessively humid, you might want to skip it. That kind of radio ten

What tools do you have to investigate further? A second radio is a big help to eavesdrop on the radio under test. Eyeball the radio for oxidation. If it was stored someplace excessively humid, you might want to skip it. That kind of radio tends to have multiple faults. Doesn't mean it can't be fixed, but it raises the challenge level in a big way.

73

The tools i have are peak atlas ESR70 plus , freq counter, b&k service master, signal gen and other radios to listen
ds to have multiple faults. Doesn't mean it can't be fixed, but it raises the challenge level in a big way.

73

What tools do you have to investigate further? A second radio is a big help to eavesdrop on the radio under test. Eyeball the radio for oxidation. If it was stored someplace excessively humid, you might want to skip it. That kind of radio tends to have multiple faults. Doesn't mean it can't be fixed, but it raises the challenge level in a big way.

73

that i can test for?

 

[DX-300]

For tools i have a peak esr70 pro / B&K servicemaster and signal generator and other radio to listening and I'm looking for an audio tracer

 

[nomadradio]

Umm, dummy load? Wattmeter?

73

 

[loosecannon]

check the "sticky threads" section at the top of this forum, just above where you see your thread posted.

in there you will find links to service info. search around until you find your radio or its equivalent because you need a road map to really do any repair.

without knowing what equipment and experience you have, but trying to be helpful, i'll just shotgun a couple of guesses.

however, if they don't end up being the issue, you're going to need to dive deeper into the world of troubleshooting because guessing really isn't the way to do this.

the first things i would check based on your first post would be IC4, the MB3756 voltage regulator, and make sure the voltages on each pin are correct.
again, you need service info to do this.

the other part that might be giving you issues is TR35. its a 2SC945 transistor and they are very common and cheap.
you might just try replacing it if you don't have the ability to test it, as it may be faster.
LC